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WO2022150497A1 - Extended-release hydrogel-drug formulations - Google Patents

Extended-release hydrogel-drug formulations Download PDF

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Publication number
WO2022150497A1
WO2022150497A1 PCT/US2022/011469 US2022011469W WO2022150497A1 WO 2022150497 A1 WO2022150497 A1 WO 2022150497A1 US 2022011469 W US2022011469 W US 2022011469W WO 2022150497 A1 WO2022150497 A1 WO 2022150497A1
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Prior art keywords
formulation
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extended
polymer
functional polymer
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French (fr)
Inventor
Laurence A. Roth
James Anthony STEFATER
Tomasz Pawel STRYJEWSKI
Jun Li
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Pykus Therapeutics Inc
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Pykus Therapeutics Inc
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    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N5/00—Undifferentiated human, animal or plant cells, e.g. cell lines; Tissues; Cultivation or maintenance thereof; Culture media therefor
    • C12N5/0068—General culture methods using substrates
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N2500/00—Specific components of cell culture medium
    • C12N2500/50—Soluble polymers, e.g. polyethyleneglycol [PEG]
    • C—CHEMISTRY; METALLURGY
    • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
    • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
    • C12N2533/00—Supports or coatings for cell culture, characterised by material
    • C12N2533/30—Synthetic polymers

Definitions

  • the invention is directed to formulations comprising polymers and polymer compositions that form extended-release hydrogels comprising a pharmaceutically active agent (e.g., a drug) and methods of using the extended-release hydrogels comprising a pharmaceutically active agent for providing targeted release of the pharmaceutically active agent to a site of interest in a subject for a variety of disorders.
  • a pharmaceutically active agent e.g., a drug
  • a pharmaceutically active agent e.g., a drug
  • Delivering a pharmaceutically active agent (e.g., a drug) to the body in an extended- release fashion provides many benefits to the subject, including more specific delivery, less off- site side-effects, more consistent and targeted control of drug dose over time, decreased frequency of drug administration, and better subject compliance.
  • a formulation for forming an extended-release hydrogel that can be injected through a cannula or needle, in particular a cannula or needle with a smaller diameter, could be directed into a wide variety of anatomical spaces, which would be clinically advantageous.
  • formulations for forming an extended-release hydrogel comprising a pharmaceutically active agent could be administered nearly anywhere in the body in a variety of ways, including but not limited to, topical, epidermal, subdermal, intra-adipose, intramuscular, intra-peritoneal, intravenous, intra- arterial, intracranial, intranasal, and/or intrauterine.
  • targeted therapy through injection of a formulation that forms an extended-release hydrogel comprising a pharmaceutically active agent into an organ directly, the wall of an organ, or into the surrounding fascia or connective tissue of an organ would be desirable and beneficial.
  • Targeted extended release of a pharmaceutically active agent is particularly compelling when the target tissue is difficult to access clinically, a sensitive area, and/or where repeat access is invasive or burdensome to the subject.
  • One compelling example is the eye.
  • the structure of the mammalian eye is divided into two segments: the anterior and posterior.
  • the anterior segment or anterior cavity is the front third of the eye and includes the cornea, iris, ciliary body, and lens.
  • the posterior segment or posterior cavity is the back two-thirds of the eye and includes the choroid, retina, optic nerve, and vitreous humor.
  • AMD age-related macular degeneration
  • proliferative diabetic retinopathy proliferative vitreoretinopathy
  • ocular malignancies inherited retinal diseases, diabetic macular edema, macular edema from retinal vein occlusions, choroidal neovascularization, uveitis, amongst others.
  • Typical routes for administration of pharmaceutically active agents include topical, systemic, subcutaneous, intravitreal, subretinal, intraocular, intracameral, suprachoroidal, subconjunctival, subtenon, intracanalicular, periobulbar and retrobulbar.
  • effective delivery of pharmaceutically active agents for treatment of back-of-the-eye diseases remains a challenge. Delivery to the posterior segment of the eye is typically achieved via an intravitreal injection, the periocular route, implant, or by systemic administration.
  • physiologic barriers to transport of the pharmaceutically active agents to the posterior segment from routes other than intravitreal injection often make their use impractical.
  • Intravitreal injection is often carried out with a 30 gauge or similar needle. While intravitreal injections offer high concentrations of pharmaceutically active agent to the vitreous chamber and retina, they can be associated with various short term complications such as retinal detachment, inflammation, elevated intraocular pressure, endophthalmitis and intravitreal hemorrhage. Injection of small particles within the vitreous may lead to wide dispersal of the particles which can obstruct vision (experienced by the patient as “floaters”). Additionally, many current formulations for administration of a pharmaceutically active agent to the eye often require frequent repeat injections (e.g., monthly), thus increasing the risk of complications and resulting in a substantial burden on both the patient and the healthcare system in general.
  • the extended-release hydrogel is formed by reaction of (a) a nucleo-functional polymer that is a biocompatible polymer containing (i) plurality of -OH groups and (ii) a plurality of thio-functional groups -R 1 -SH wherein R 1 is an ester-containing linker and (b) an electro-functional polymer that is a biocompatible polymer containing at least one thiol-reactive group, such as an alpha-beta unsaturated ester.
  • formulations are provided comprising a nucleo-functional polymer, an electro-functional polymer and a pharmaceutically active agent in a pharmaceutically acceptable carrier.
  • formulations comprising a nucleo-functional polymer and a pharmaceutically active agent in a pharmaceutically acceptable carrier.
  • formulations are provided comprising an electro-functional polymer and a pharmaceutically active agent in a pharmaceutically acceptable carrier.
  • the nucleo-functional polymer and electro-functional polymer formulations are desirably low-viscosity solutions that can be injected easily into the target tissue of a subject through a narrow-gauge needle, thereby permitting administration of the polymers while minimizing trauma to certain sensitive structures, like injection into the subject’s eye.
  • the nucleo-functional polymer and electro-functional polymer begin to react once mixed; the reaction between the nucleo-functional polymer and electro-functional polymer to create an extended-release hydrogel comprising a pharmaceutically active agent occurs when the polymers are mixed prior to delivery to the subject’s target site, as they are delivered to the subject’s target site, and/or within the target site of the subject thereby forming a hydrogel in situ in the target site of the subject that immobilizes the pharmaceutical agent from immediate dispersal and provides for extended-release of the pharmaceutical agent.
  • the pharmaceutically active agent diffuses out of the hydrogel and into the local environment over a period of time, i.e., extended-release, that provides for therapeutically effective longer-term therapy than what would be achieved by injection of the pharmaceutically active agent alone.
  • the pharmaceutically active agent may be dissolved in the extended-release hydrogel-forming formulation, suspended within the extended-release hydrogel-forming formulation and/or encapsulated within a particle and dispersed within the extended-release hydrogel-forming formulation.
  • features of the extended-release hydrogel-forming formulation and/or extended-release hydrogel include: materials that are non-toxic, varying crosslink density or porosity, varying reaction kinetics and varying biodegradation rate, all of which are appropriate to the desired method of administration, the desired target site in the subject, and the timeframe desired for the extended-release of the pharmaceutical into the environment surrounding the target site.
  • a formulation for forming an extended-release hydrogel comprising: a. a nucleo-functional polymer that is a biocompatible polymer containing a plurality of thio-functional groups -R 1 -SH wherein R 1 is an ester-containing linker; b. an electro- functional polymer that is a biocompatible polymer containing at least one thiol-reactive group; c. a pharmaceutical agent; and d. a pharmaceutically acceptable carrier.
  • E2 The formulation of embodiment E1, wherein the nucleo-functional polymer is a biocompatible polymer comprising poly(vinyl alcohol).
  • nucleo-functional polymer comprises a biocompatible poly(vinyl alcohol) polymer substituted by a plurality of thio-functional groups -R 1 -SH.
  • nucleo-functional polymer comprises a biocompatible, partially hydrolyzed poly(vinyl alcohol).
  • the partially hydrolyzed poly(vinyl alcohol) polymer has a degree of hydrolysis in the range of about 75% to about 99.9%.
  • nucleo- functional polymer is a biocompatible poly(vinyl alcohol) polymer comprising: wherein a is an integer from 1 to about 20, b is an integer from 1 to about 20, and c is an integer from about 20 to about 500.
  • a is an integer from 1 to about 20
  • b is an integer from 1 to about 20
  • c is an integer from about 20 to about 500.
  • E11 The formulation of any one of embodiments E1-E10, wherein the nucleo-functional polymer has a weight-average molecular weight in the range of from about 15,000 g/mol to about 25,000 g/mol.
  • any one of embodiments E1-E9, wherein the nucleo-functional polymer has a weight-average molecular weight of less than about 75,000 g/mol.
  • E13. The formulation of any one of embodiments E1-E12, wherein the electro-functional polymer is a biocompatible polymer comprising poly(ethylene glycol).
  • E14. The formulation of any one of embodiments E1-E13, wherein the electro-functional polymer is a biocompatible polymer comprising poly(ethylene glycol)polymer substituted by at least one thiol-reactive group.
  • any one of embodiments E1-E17, wherein the electro- functional polymer has a weight-average molecular weight in the range of from about 500 g/mol to about 100,000 g/mol. E19.
  • any one of embodiments E1-E20, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 2,700 g/mol to about 3,000 g/mol. E22.
  • the formulation of any one of embodiments E1-E19, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 18,000 g/mol to about 22,000 g/mol. E24.
  • any one of embodiments E1-E23, wherein the electro-functional polymer comprises a multi-arm polymer.
  • E25. The formulation of embodiment E24, wherein the multi- arm polymer comprises as 4-arm polyethylene glycol maleimide, 4-arm polyethylene glycol acrylate, 4-arm polyethylene glycol vinyl sulfone, 8-arm polyethylene glycol maleimide, 8-arm polyethylene glycol acrylate, 8-arm polyethylene glycol vinyl sulfone, or combinations thereof.
  • E26 The formulation of any one of embodiments E1-E25, wherein the mole ratio of (i) thio- functional groups -R 1 -SH to (ii) thiol-reactive group is in the range of about 10:1 to about 1:10.
  • E27 The formulation of any one of embodiments E1-E26, wherein the mole ratio of (i) thio- functional groups -R 1 -SH to (ii) thiol-reactive groups is in the range of about 2:1 to about 1:2.
  • E28 The formulation of any one of embodiments E1-E25, wherein the mole ratio of (i) thio- functional groups -R 1 -SH to (ii) thiol-reactive groups is in the range of about 0.8:1 to about 1.2:1.
  • E29 The formulation of any one of embodiments E1-E28, wherein the formulation comprises water, and the formulation has a pH in the range of about 7.1 to about 7.7. E30.
  • any one of embodiments E1-E28 wherein the formulation comprises water, and the formulation has a pH in the range of about 7.3 to about 7.5.
  • E31 The formulation of any one of embodiments E1-E28, wherein the formulation comprises water, and the formulation has a pH of about 7.4.
  • E32 The formulation of any one of embodiments E1-E31, further comprising an alkali metal salt.
  • E33 The formulation of any one of embodiments E1-E32, further comprising an alkali metal halide salt, an alkaline earth metal halide salt, or a combination thereof.
  • E34 The formulation of any one of embodiments E1-E33, further comprising sodium chloride, potassium chloride, calcium chloride, magnesium chloride, or a combination thereof.
  • E35 The formulation of any one of embodiments E1-E34, wherein the formulation has an osmolality in the range of about 200 mOsm / kg to about 400 mOsm / kg.
  • E36 The formulation of any one of embodiments E1-E35, wherein the formulation has an osmolality in the range of about 250 mOsm / kg to about 350 mOsm / kg.
  • E37 The formulation of any one of embodiments E1-E36, wherein the formulation has an osmolality in the range of about 280 mOsm / kg to about 320 mOsm / kg. E38.
  • E40 The formulation of any one of embodiments E1-E39, wherein the formulation has less than about 50 particles per mL with a size of ⁇ 10 ⁇ m.
  • E41 The formulation of any one of embodiments E1-E39, wherein the formulation has less than about 5 particles per mL with a size of ⁇ 25 ⁇ m.
  • E42 The formulation of any one of embodiments E1-E41, wherein the hydrogel formed by the formulation has a transparency of at least about 80% for light in the visible spectrum when measured through a hydrogel having a thickness of 2 cm.
  • any one of embodiments E1-E42 wherein the hydrogel formed by the formulation has a transparency of at least about 85% for light in the visible spectrum when measured through a hydrogel having a thickness of 2 cm.
  • E44 The formulation of any one of embodiments E1-E43, wherein the hydrogel formed by the formulation has a transparency or at least about 90% for light in the visible spectrum when measured through a hydrogel having a thickness of 2 cm.
  • E45 The formulation of any one of embodiments E1-E42, wherein the hydrogel formed by the formulation has a transparency of at least about 85% for light in the visible spectrum when measured through a hydrogel having a thickness of 2 cm.
  • any one of embodiments E1-E44 wherein the hydrogel formed by the formulation has a crosslink time of less than about 10 minutes, less than about 7 minutes, less than about 5 minutes, less than about 3 minutes, less than about 1 minute, less than about 20 seconds, less than about 10 seconds, less than about 5 seconds, or less than about 1 second when measured at 37°C.
  • E46 The formulation of any one of embodiments E1-E45, wherein the hydrogel formed by the formulation has a degradation time that is greater than or equal to about 3, about 5, about 8, about 10, about 13, about 14, about 15, about 19, or about 32 days at 60°C. E47.
  • any one of embodiments E1-E45 wherein the hydrogel formed by the formulation has a degradation time that is greater than or equal to about 20, about 40, about 60, about 69, about 80, about 94, about 100, or about 158 days at 37°C.
  • E48 The formulation of any one of embodiments E1-E47, wherein the hydrogel formed by the formulation acts as a depot for the pharmaceutical agent.
  • E49 The formulation of any one of embodiments E1-E48, wherein the hydrogel formed by the formulation provides for extended-release of the pharmaceutical agent.
  • E50 The formulation of any one of embodiments E1-E45, wherein the hydrogel formed by the formulation has a degradation time that is greater than or equal to about 20, about 40, about 60, about 69, about 80, about 94, about 100, or about 158 days at 37°C.
  • any one of embodiments E1-E49 wherein the hydrogel formed by the formulation releases the pharmaceutical agent over a period of at least about 5, about 10, about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, about 100, or about 120 days.
  • E51 The formulation of any one of embodiments E1-E50, wherein complete release of the pharmaceutical agent from the hydrogel formed by the formulation is achieved after at least about 10, about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, about 100, about 110, about 120, about 130 days.
  • E52 The formulation of any one of embodiments E1-E51, where the hydrogel formed by the formulation comprises a nearly first-order release of the pharmaceutical agent.
  • any one of embodiments E1-E52 wherein the formulation has a viscosity of less than about 4000 cP, about 2000 cP, about 1000 cP, about 800 cP, about 600 cP, about 500 cP, about 400 cP, about 200 cP, about 100 cP, about 80 cP, about 60 cP, about 50 cP, about 40 cP, about 20 cP, about 10 cP, about 8 cP, about 6 cP, about 5 cP, about 4 cP, about 3 cP, about 2 cP about 1 cP prior to formation of the hydrogel.
  • E54 The formulation of any one of embodiments E1-E52, wherein the formulation has a viscosity of less than about 4000 cP, about 2000 cP, about 1000 cP, about 800 cP, about 600 cP, about 500 cP, about 400 cP, about 200 cP, about 100 cP, about 80 c
  • any one of embodiments E1-E53 wherein the pharmaceutical agent comprises an anti- inflammatory agent, a steroid, an NSAID, an intraocular pressure lowering drug, an antibiotic, a pain reliever, an inhibitor of vascular endothelial growth factor (VEGF), an inhibitor of abnormal vascular growth or vascular leakage, an inhibitor or modifier of the complement pathway, a neuroprotectant, an inhibitor of abnormal cell proliferation, a chemotherapeutic, an anti-viral drug, a gene therapy viral vector, or a combination thereof.
  • the pharmaceutical agent comprises an anti- inflammatory agent, a steroid, an NSAID, an intraocular pressure lowering drug, an antibiotic, a pain reliever, an inhibitor of vascular endothelial growth factor (VEGF), an inhibitor of abnormal vascular growth or vascular leakage, an inhibitor or modifier of the complement pathway, a neuroprotectant, an inhibitor of abnormal cell proliferation, a chemotherapeutic, an anti-viral drug, a gene therapy viral vector, or a combination thereof.
  • any one of embodiments E1-E54 wherein the pharmaceutical agent comprises a small molecule, a protein, a DNA or RNA fragment, a glycosaminoglycan, a carbohydrate, a nucleic acid, an inorganic and organic biologically active compound, an active portion of any of the proceeding, or a combination thereof.
  • the pharmaceutical agent comprises an antibody, a bi-specific antibody, a single-chain variable fragment (scFv), an active portion of any of the proceeding, or a combination thereof.
  • the pharmaceutical agent comprises an anti-cancer agent.
  • nucleo-functional polymer that is a biocompatible polymer containing a plurality of thio-functional groups -R 1 -SH wherein R 1 is an ester-containing linker; b. a pharmaceutical agent; and c. a pharmaceutically acceptable carrier.
  • the nucleo-functional polymer is a biocompatible polymer comprising poly(vinyl alcohol).
  • the nucleo- functional polymer comprises a biocompatible poly(vinyl alcohol) polymer substituted by a plurality of thio-functional groups -R 1 -SH.
  • nucleo-functional polymer comprises a biocompatible, partially hydrolyzed poly(vinyl alcohol).
  • nucleo-functional polymer comprises a biocompatible, partially hydrolyzed poly(vinyl alcohol).
  • E67. The formulation of embodiment 66, wherein the partially hydrolyzed poly(vinyl alcohol) polymer has a degree of hydrolysis in the range of about 75% to about 99.9%.
  • E68. The formulation of any one of embodiments E63-E67, wherein the thio- functional group -R 1 -SH is -OC(O)-(C 1 -C 6 alkylene)-SH.
  • E70. The formulation of embodiment 63, wherein the nucleo-functional polymer is a biocompatible poly(vinyl alcohol) polymer comprising: wherein a is an integer from 1 to about 20 and b is an integer from 1 to about 20.
  • E71. The formulation of embodiment 63, wherein the nucleo-functional polymer is a biocompatible poly(vinyl alcohol) polymer comprising: wherein a is an integer from 1 to about 20, b is an integer from 1 to about 20, and c is an integer from about 20 to about 500.
  • E74 The formulation of any one of embodiments E63-E71, wherein the nucleo-functional polymer has a weight-average molecular weight of less than about 75,000 g/mol. E75.
  • E80 The formulation of any one of embodiments E63-E79, further comprising sodium chloride, potassium chloride, calcium chloride, magnesium chloride, or a combination thereof.
  • E81. The formulation of any one of embodiments E63-E80, wherein the formulation has an osmolality in the range of about 200 mOsm / kg to about 400 mOsm / kg.
  • E82. The formulation of any one of embodiments E63-E81, wherein the formulation has an osmolality in the range of about 250 mOsm / kg to about 350 mOsm / kg.
  • E83 The formulation of any one of embodiments E63-E79, further comprising sodium chloride, potassium chloride, calcium chloride, magnesium chloride, or a combination thereof.
  • any one of embodiments E63-E84 wherein the formulation has an endotoxin level of less than about 20 endotoxin units/ml, less than about 15 endotoxin units/ml, less than about 10 endotoxin units/ml, less than about 5 endotoxin units/ml, less than about 2.5 endotoxin units/ml, less than about 1.0 endotoxin units/ml, less than about 0.8 endotoxin units/ml, less than about 0.5 endotoxin units/ml, less than about 0.2 endotoxin units/ml, or less than about 0.1 endotoxin units/ml.
  • endotoxin level of less than about 20 endotoxin units/ml, less than about 15 endotoxin units/ml, less than about 10 endotoxin units/ml, less than about 5 endotoxin units/ml, less than about 2.5 endotoxin units/ml, less than about 1.0 end
  • any one of embodiments E63-E87 wherein the formulation has a viscosity of less than about 4000 cP, about 2000 cP, about 1000 cP, about 800 cP, about 600 cP, about 500 cP, about 400 cP, about 200 cP, about 100 cP, about 80 cP, about 60 cP, about 50 cP, about 40 cP, about 20 cP, about 10 cP, about 8 cP, about 6 cP, about 5 cP, about 4 cP, about 3 cP, about 2 cP about 1 cP prior to formation of the hydrogel.
  • E89 The formulation of any one of embodiments E63-E87, wherein the formulation has a viscosity of less than about 4000 cP, about 2000 cP, about 1000 cP, about 800 cP, about 600 cP, about 500 cP, about 400 cP, about 200 cP, about 100 cP, about 80 c
  • any one of embodiments E63-E88 wherein the pharmaceutical agent comprises an anti- inflammatory agent, a steroid, an NSAID, an intraocular pressure lowering drug, an antibiotic, a pain reliever, an inhibitor of vascular endothelial growth factor (VEGF), an inhibitor of abnormal vascular growth or vascular leakage, an inhibitor of abnormal cell proliferation, a chemotherapeutic, an anti-viral drug, a gene therapy viral vector, or a combination thereof.
  • the pharmaceutical agent comprises an anti- inflammatory agent, a steroid, an NSAID, an intraocular pressure lowering drug, an antibiotic, a pain reliever, an inhibitor of vascular endothelial growth factor (VEGF), an inhibitor of abnormal vascular growth or vascular leakage, an inhibitor of abnormal cell proliferation, a chemotherapeutic, an anti-viral drug, a gene therapy viral vector, or a combination thereof.
  • VEGF vascular endothelial growth factor
  • any one of embodiments E63-E89 wherein the pharmaceutical agent comprises a small molecule, a protein, a DNA or RNA fragment, a glycosaminoglycan, a carbohydrate, a nucleic acid, an inorganic and organic biologically active compound, an active portion of any of the proceeding, or a combination thereof.
  • the pharmaceutical agent comprises an antibody, a bi-specific antibody, a single-chain variable fragment (scFv), an active portion of any of the proceeding, or a combination thereof.
  • the pharmaceutical agent comprises an anti-cancer agent.
  • an electro-functional polymer that is a biocompatible polymer containing at least one thiol-reactive group; b. a pharmaceutical agent; and c. a pharmaceutically acceptable carrier.
  • E99. The formulation of embodiment 98, wherein the electro-functional polymer is a biocompatible polymer comprising poly(ethylene glycol).
  • E100. The formulation of embodiment 98 or 99, wherein the electro-functional polymer is a biocompatible polymer comprising poly(ethylene glycol)polymer substituted by at least one thiol-reactive group.
  • E101 The formulation of any one of embodiments E98-E100, wherein the thiol-reactive group is an alpha- beta unsaturated ester, maleimidyl, sulfone, or combinations thereof.
  • any one of embodiments E98-E107, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 9,000 g/mol to about 11,000 g/mol. E109.
  • the formulation of any one of embodiments E98-E108, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 18,000 g/mol to about 22,000 g/mol. E110.
  • the formulation of any one of embodiments E98-E109, wherein the electro- functional polymer comprises a multi-arm polymer. E111.
  • any one of embodiments E98- E117 wherein the formulation has an osmolality in the range of about 200 mOsm / kg to about 400 mOsm / kg.
  • E119 The formulation of any one of embodiments E98-E118, wherein the formulation has an osmolality in the range of about 250 mOsm / kg to about 350 mOsm / kg.
  • E120 The formulation of any one of embodiments E98-E119, wherein the formulation has an osmolality in the range of about 280 mOsm / kg to about 320 mOsm / kg.
  • E121 The formulation of any one of embodiments E98- E117, wherein the formulation has an osmolality in the range of about 200 mOsm / kg to about 400 mOsm / kg.
  • E123 The formulation of any one of embodiments E98-E122, wherein the formulation has less than about 50 particles per mL with a size of ⁇ 10 ⁇ m.
  • E124 The formulation of any one of embodiments E98-E123, wherein the formulation has less than about 5 particles per mL with a size of ⁇ 25 ⁇ m.
  • E125 The formulation of any one of embodiments E98-E122, wherein the formulation has less than about 50 particles per mL with a size of ⁇ 10 ⁇ m.
  • any one of embodiments E98-E124 wherein the formulation has a viscosity of less than about 4000 cP, about 2000 cP, about 1000 cP, about 800 cP, about 600 cP, about 500 cP, about 400 cP, about 200 cP, about 100 cP, about 80 cP, about 60 cP, about 50 cP, about 40 cP, about 20 cP, about 10 cP, about 8 cP, about 6 cP, about 5 cP, about 4 cP, about 3 cP, about 2 cP about 1 cP prior to formation of the hydrogel.
  • E126 The formulation of any one of embodiments E98-E124, wherein the formulation has a viscosity of less than about 4000 cP, about 2000 cP, about 1000 cP, about 800 cP, about 600 cP, about 500 cP, about 400 cP, about 200 cP, about 100 cP, about 80 c
  • any one of embodiments E98-E125 wherein the pharmaceutical agent comprises an anti-inflammatory agent, a steroid, an NSAID, an intraocular pressure lowering drug, an antibiotic, a pain reliever, an inhibitor of vascular endothelial growth factor (VEGF), an inhibitor of abnormal vascular growth or vascular leakage, an inhibitor of abnormal cell proliferation, a chemotherapeutic, an anti-viral drug, a gene therapy viral vector, or a combination thereof.
  • the pharmaceutical agent comprises an anti-inflammatory agent, a steroid, an NSAID, an intraocular pressure lowering drug, an antibiotic, a pain reliever, an inhibitor of vascular endothelial growth factor (VEGF), an inhibitor of abnormal vascular growth or vascular leakage, an inhibitor of abnormal cell proliferation, a chemotherapeutic, an anti-viral drug, a gene therapy viral vector, or a combination thereof.
  • VEGF vascular endothelial growth factor
  • any one of embodiments E98-E126 wherein the pharmaceutical agent comprises a small molecule, a protein, a DNA or RNA fragment, a glycosaminoglycan, a carbohydrate, a nucleic acid, an inorganic and organic biologically active compound, an active portion of any of the proceeding, or a combination thereof.
  • the pharmaceutical agent comprises an antibody, a bi-specific antibody, a single- chain variable fragment (scFv), an active portion of any of the proceeding, or a combination thereof.
  • scFv single- chain variable fragment
  • nucleo-functional polymer that is a biocompatible polymer containing a plurality of thio-functional groups -R1-SH wherein R1 is an ester-containing linker; b. an electro-functional polymer that is a biocompatible polymer containing at least one thiol-reactive group; and c. a pharmaceutical agent.
  • E136. The extended- release hydrogel of embodiment 135, further comprising a pharmaceutically acceptable carrier.
  • nucleo-functional polymer is a biocompatible polymer comprising poly(vinyl alcohol).
  • E143. The extended-release hydrogel of embodiment 135, wherein the nucleo-functional polymer is a biocompatible poly(vinyl alcohol) polymer comprising: wherein a is an integer from 1 to about 20 and b is an integer from 1 to about 20. E144.
  • E145. The extended- release hydrogel of any one of embodiments E135-E144, wherein the nucleo-functional polymer has a weight-average molecular weight in the range of from about 4,000 g/mol to about 100,000 g/mol. E146.
  • the extended-release hydrogel of any one of embodiments E135-E147, wherein the electro-functional polymer is a biocompatible polymer comprising poly(ethylene glycol). E149.
  • E152 The extended-release hydrogel of any one of embodiments E135-E151, wherein the thiol-reactive group is acrylate, maleimide, or vinylsulfone.
  • E153 The extended- release hydrogel of any one of embodiments E135-E152, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 500 g/mol to about 100,000 g/mol.
  • E154 The extended-release hydrogel of any one of embodiments E135-E153, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 1,000 g/mol to about 50,000 g/mol.
  • E155 The extended-release hydrogel of any one of embodiments E135-E151, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 1,000 g/mol to about 50,000 g/mol.
  • the extended-release hydrogel of embodiment 159 wherein the multi-arm polymer comprises as 4-arm polyethylene glycol maleimide, 4-arm polyethylene glycol acrylate, 4-arm polyethylene glycol vinyl sulfone, 8-arm polyethylene glycol maleimide, 8-arm polyethylene glycol acrylate, 8-arm polyethylene glycol vinyl sulfone, or combinations thereof.
  • E161 The extended-release hydrogel of any one of embodiments E135-E160, wherein the mole ratio of (i) thio-functional groups -R 1 -SH to (ii) thiol-reactive group is in the range of about 10:1 to about 1:10. E162.
  • the extended-release hydrogel of any one of embodiments E135-E161, wherein the mole ratio of (i) thio-functional groups -R 1 -SH to (ii) thiol-reactive groups is in the range of about 0.8:1 to about 1.2:1.
  • E164. The extended-release hydrogel of any one of embodiments E135-E163, wherein the formulation comprises water, and the formulation has a pH in the range of about 7.1 to about 7.7. E165.
  • E176 The extended-release hydrogel of any one of embodiments E135-E175, wherein the extended-release hydrogel acts as a depot for the pharmaceutical agent. E177.
  • E178. The extended-release hydrogel of any one of embodiments E135-E177, wherein the extended-release hydrogel releases the pharmaceutical agent over a period of at least about 5, about 10, about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, about 100, or about 120 days.
  • E180 The extended-release hydrogel of any one of embodiments E135-E179, where the extended-release hydrogel comprises a nearly first-order release of the pharmaceutical agent.
  • the pharmaceutical agent comprises an anti-inflammatory agent, a steroid, an NSAID, an intraocular pressure lowering drug, an antibiotic, a pain reliever, an inhibitor of vascular endothelial growth factor (VEGF), an inhibitor of abnormal vascular growth or vascular leakage, an inhibitor of abnormal cell proliferation, a chemotherapeutic, an anti-viral drug, a gene therapy viral vector, or a combination thereof.
  • the pharmaceutical agent comprises an anti-inflammatory agent, a steroid, an NSAID, an intraocular pressure lowering drug, an antibiotic, a pain reliever, an inhibitor of vascular endothelial growth factor (VEGF), an inhibitor of abnormal vascular growth or vascular leakage, an inhibitor of abnormal cell proliferation, a chemotherapeutic, an anti-viral drug, a gene therapy viral vector, or a combination thereof.
  • the pharmaceutical agent comprises an antibody, a bi-specific antibody, a single-chain variable fragment (scFv), an active portion of any of the proceeding, or a combination thereof.
  • the extended- release hydrogel of any one of embodiments E136-E186, wherein the pharmaceutically acceptable carrier comprises PBS.
  • E190 A method for administering a pharmaceutical agent to a subject in need thereof, the method comprising: a. administering to the subject an effective amount of a nucleo- functional polymer, an electro-functional polymer, a pharmaceutical agent, and a pharmaceutically acceptable carrier; and b.
  • nucleo-functional polymer is a biocompatible polymer containing a plurality of thio- functional groups -R 1 -SH wherein R 1 is an ester-containing linker
  • the electro- functional polymer is a biocompatible polymer containing at least one thiol-reactive group.
  • nucleo-functional polymer and the electro-functional polymer are administered to the subject in separate formulations and following administration to the subject, the nucleo-functional polymer and the electro-functional polymer mix and react to form the extended-release hydrogel in the subject.
  • the formulation comprising the nucleo-functional polymer comprises the pharmaceutical agent.
  • the formulation comprising the electro-functional polymer comprises the pharmaceutical agent.
  • E195. The method of any one of embodiments E192-E194, wherein the formulation comprising the nucleo-functional polymer comprises the pharmaceutically acceptable carrier.
  • the formulation comprising the electro-functional polymer comprises the pharmaceutically acceptable carrier.
  • E197. The method of any one of embodiments E190-E196, wherein the nucleo-functional polymer is a biocompatible polymer comprising poly(vinyl alcohol).
  • E198. The method of any one of embodiments E190-E197, wherein the nucleo- functional polymer comprises a biocompatible poly(vinyl alcohol) polymer substituted by a plurality of thio-functional groups -R 1 -SH.
  • E199 The method of any of embodiments E190- E198, wherein the nucleo-functional polymer comprises a biocompatible, partially hydrolyzed poly(vinyl alcohol).
  • nucleo-functional polymer is a biocompatible poly(vinyl alcohol) polymer comprising: wherein a is an integer from 1 to about 20 and b is an integer from 1 to about 20.
  • E204. The method of any one of embodiments E190-E196, wherein the nucleo-functional polymer is a biocompatible poly(vinyl alcohol) polymer comprising: wherein a is an integer from 1 to about 20, b is an integer from 1 to about 20, and c is an integer from about 20 to about 500.
  • E206 The method of any one of embodiments E190-E205, wherein the nucleo-functional polymer has a weight-average molecular weight in the range of from about 15,000 g/mol to about 25,000 g/mol.
  • E207 The method of any one of embodiments E190-E206, wherein the nucleo-functional polymer has a weight-average molecular weight of less than about 75,000 g/mol. E208.
  • electro-functional polymer is a biocompatible polymer comprising poly(ethylene glycol).
  • electro-functional polymer is a biocompatible polymer comprising poly(ethylene glycol)polymer substituted by at least one thiol-reactive group.
  • the thiol-reactive group is an alpha-beta unsaturated ester, maleimidyl, sulfone, or combinations thereof.
  • the multi-arm polymer comprises as 4-arm polyethylene glycol maleimide, 4-arm polyethylene glycol acrylate, 4-arm polyethylene glycol vinyl sulfone, 8-arm polyethylene glycol maleimide, 8-arm polyethylene glycol acrylate, 8-arm polyethylene glycol vinyl sulfone, or combinations thereof.
  • E221. The method of any one of embodiments E190-E220, wherein the mole ratio of (i) thio-functional groups -R 1 -SH to (ii) thiol-reactive group is in the range of about 10:1 to about 1:10. E222.
  • E230. The method of any one of embodiments E191-E229, wherein the formulation has an osmolality in the range of about 200 mOsm / kg to about 400 mOsm / kg.
  • E231. The method of any one of embodiments E191-E230, wherein the formulation has an osmolality in the range of about 250 mOsm / kg to about 350 mOsm / kg.
  • any one of embodiments E191-E233 wherein the formulation has an endotoxin level of less than about 20 endotoxin units/ml, less than about 15 endotoxin units/ml, less than about 10 endotoxin units/ml, less than about 5 endotoxin units/ml, less than about 2.5 endotoxin units/ml, less than about 1.0 endotoxin units/ml, less than about 0.8 endotoxin units/ml, less than about 0.5 endotoxin units/ml, less than about 0.2 endotoxin units/ml, or less than about 0.1 endotoxin units/ml.
  • E235 E235.
  • E236 The method of any one of embodiments E191-E235, wherein the formulation has less than about 5 particles per mL with a size of ⁇ 25 ⁇ m.
  • E237 The method of any one of embodiments E190-E236, wherein the extended-release hydrogel has a transparency of at least about 80% for light in the visible spectrum when measured through a hydrogel having a thickness of 2 cm. E238.
  • any one of embodiments E190-E247 wherein the formulation has a viscosity of less than about 4000 cP, about 2000 cP, about 1000 cP, about 800 cP, about 600 cP, about 500 cP, about 400 cP, about 200 cP, about 100 cP, about 80 cP, about 60 cP, about 50 cP, about 40 cP, about 20 cP, about 10 cP, about 8 cP, about 6 cP, about 5 cP, about 4 cP, about 3 cP, about 2 cP about 1 cP prior to formation of the hydrogel.
  • the formulation has a viscosity of less than about 4000 cP, about 2000 cP, about 1000 cP, about 800 cP, about 600 cP, about 500 cP, about 400 cP, about 200 cP, about 100 cP, about 80 cP, about 60 cP, about 50 cP, about 40
  • the pharmaceutical agent comprises an anti-inflammatory agent, a steroid, an NSAID, an intraocular pressure lowering drug, an antibiotic, a pain reliever, an inhibitor of vascular endothelial growth factor (VEGF), an inhibitor of abnormal vascular growth or vascular leakage, an inhibitor of abnormal cell proliferation, a chemotherapeutic, an anti-viral drug, a gene therapy viral vector, or a combination thereof.
  • the pharmaceutical agent comprises an anti-inflammatory agent, a steroid, an NSAID, an intraocular pressure lowering drug, an antibiotic, a pain reliever, an inhibitor of vascular endothelial growth factor (VEGF), an inhibitor of abnormal vascular growth or vascular leakage, an inhibitor of abnormal cell proliferation, a chemotherapeutic, an anti-viral drug, a gene therapy viral vector, or a combination thereof.
  • any one of embodiments E190- E249 wherein the pharmaceutical agent comprises a small molecule, a protein, a DNA or RNA fragment, a glycosaminoglycan, a carbohydrate, a nucleic acid, an inorganic and organic biologically active compound, an active portion of any of the proceeding, or a combination thereof.
  • the pharmaceutical agent comprises an antibody, a bi-specific antibody, a single-chain variable fragment (scFv), an active portion of any of the proceeding, or a combination thereof.
  • the pharmaceutical agent comprises an anti-cancer agent.
  • any one of embodiments E190-E257 wherein the nucleo-functional polymer, the electro-functional polymer, the pharmaceutical agent, and the pharmaceutically acceptable carrier are administered to the eye of a subject.
  • E259. The method of embodiment 258, wherein the nucleo-functional polymer, the electro-functional polymer, the pharmaceutical agent, and the pharmaceutically acceptable carrier are administered to the vitreous cavity.
  • E260. The method of embodiment 259, wherein the vitreous cavity comprises vitreous.
  • E261. The method of any one of embodiments E258-E260, wherein the nucleo-functional polymer, the electro-functional polymer, the pharmaceutical agent, and the pharmaceutically acceptable carrier are administered as an intravitreal injection. E261.
  • AMD age-related macular degeneration
  • proliferative diabetic retinopathy proliferative vitreoretinopathy
  • ocular malignancies inherited retinal diseases
  • diabetic macular edema diabetic macular edema
  • macular edema from retinal vein occlusions
  • FIGURE 1 shows the release of FITC-Dextran over time from exemplary extended- release hydrogels described herein.
  • FIGURE 2 shows the release of FITC-Dextran over time from an exemplary extended-release hydrogel described herein.
  • FIGURES 3A and 3B show the release of a large protein, Bevacizumab, from exemplary extended-release hydrogels described herein.
  • FIGURE 4 shows the release of an encapsulated small molecule, tacrolimus, from an exemplary extended-release hydrogel described herein.
  • FIGURE 5 shows the release of a large protein, Bevacizumab, from an exemplary extended-release hydrogel described herein.
  • DETAILED DESCRIPTION OF THE INVENTION [0022] Various aspects of the invention are set forth below in sections; however, aspects of the invention described in one particular section are not to be limited to any particular section and are applicable to other sections as appropriate and as would be understood by those of ordinary skill in the art. DEFINITIONS [0023] To facilitate an understanding of the present invention, a number of terms and phrases are defined below. [0024] The terms “a” and “an” as used herein mean “one or more” and include the plural unless the context is inappropriate.
  • alkyl refers to a saturated straight or branched hydrocarbon, such as a straight or branched group of 1-12, 1-10, or 1-6 carbon atoms, referred to herein as C 1 -C 12 alkyl, C 1 -C 10 alkyl, and C 1 -C 6 alkyl, respectively.
  • Exemplary alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, 2-methyl-1-propyl, 2-methyl-2- propyl, 2-methyl-1-butyl, 3-methyl-1-butyl, 2-methyl-3-butyl, 2,2-dimethyl-1-propyl, 2-methyl- 1-pentyl, 3-methyl-1-pentyl, 4-methyl-1-pentyl, 2-methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl- 2-pentyl, 2,2-dimethyl-1-butyl, 3,3-dimethyl-1-butyl, 2-ethyl-1-butyl, butyl, isobutyl, t-butyl, pentyl, isopentyl, neopentyl, hexyl, heptyl, octyl, etc.
  • cycloalkyl refers to a monovalent saturated cyclic, bicyclic, or bridged cyclic (e.g., adamantyl) hydrocarbon group of 3-12, 3-8, 4-8, or 4-6 carbons, referred to herein, e.g., as "C 4-8 cycloalkyl," derived from a cycloalkane.
  • exemplary cycloalkyl groups include, but are not limited to, cyclohexanes, cyclopentanes, cyclobutanes and cyclopropanes.
  • aryl is art-recognized and refers to a carbocyclic aromatic group.
  • aryl groups include phenyl, naphthyl, anthracenyl, and the like. Unless specified otherwise, the aromatic ring may be substituted at one or more ring positions with, for example, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, alkoxyl, amino, nitro, sulfhydryl, imino, amido, carboxylic acid, -C(O)alkyl, -CO 2 alkyl, carbonyl, carboxyl, alkylthio, sulfonyl, sulfonamido, sulfonamide, ketone, aldehyde, ester, heterocyclyl, aryl or heteroaryl moieties, -CF3, -CN, or the like.
  • aryl also includes polycyclic ring systems having two or more carbocyclic rings in which two or more carbons are common to two adjoining rings (the rings are “fused rings”) wherein at least one of the rings is aromatic, e.g., the other cyclic rings may be cycloalkyls, cycloalkenyls, cycloalkynyls, and/or aryls.
  • the aromatic ring is substituted at one or more ring positions with halogen, alkyl, hydroxyl, or alkoxyl. In certain other embodiments, the aromatic ring is not substituted, i.e., it is unsubstituted.
  • heteroaryl refers to an alkyl group substituted with an aryl group.
  • heteroaryl is art-recognized and refers to aromatic groups that include at least one ring heteroatom. In certain instances, a heteroaryl group contains 1, 2, 3, or 4 ring heteroatoms. Representative examples of heteroaryl groups include pyrrolyl, furanyl, thiophenyl, imidazolyl, oxazolyl, thiazolyl, triazolyl, pyrazolyl, pyridinyl, pyrazinyl, pyridazinyl and pyrimidinyl, and the like.
  • the heteroaryl ring may be substituted at one or more ring positions with, for example, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, alkoxyl, amino, nitro, sulfhydryl, imino, amido, carboxylic acid, -C(O)alkyl, -CO 2 alkyl, carbonyl, carboxyl, alkylthio, sulfonyl, sulfonamido, sulfonamide, ketone, aldehyde, ester, heterocyclyl, aryl or heteroaryl moieties, -CF 3 , -CN, or the like.
  • heteroaryl also includes polycyclic ring systems having two or more rings in which two or more carbons are common to two adjoining rings (the rings are “fused rings”) wherein at least one of the rings is heteroaromatic, e.g., the other cyclic rings may be cycloalkyls, cycloalkenyls, cycloalkynyls, and/or aryls.
  • the heteroaryl ring is substituted at one or more ring positions with halogen, alkyl, hydroxyl, or alkoxyl. In certain other embodiments, the heteroaryl ring is not substituted, i.e., it is unsubstituted.
  • heteroarylkyl refers to an alkyl group substituted with a heteroaryl group.
  • ortho, meta and para are art-recognized and refer to 1,2-, 1,3- and 1,4- disubstituted benzenes, respectively.
  • 1,2-dimethylbenzene and ortho- dimethylbenzene are synonymous.
  • heterocyclyl and heterocyclic group are art-recognized and refer to saturated or partially unsaturated 3- to 10-membered ring structures, alternatively 3- to 7- membered rings, whose ring structures include one to four heteroatoms, such as nitrogen, oxygen, and sulfur.
  • the number of ring atoms in the heterocyclyl group can be specified using C x - C x nomenclature where x is an integer specifying the number of ring atoms.
  • a C3-C7heterocyclyl group refers to a saturated or partially unsaturated 3- to 7-membered ring structure containing one to four heteroatoms, such as nitrogen, oxygen, and sulfur.
  • the designation “C 3 -C 7 ” indicates that the heterocyclic ring contains a total of from 3 to 7 ring atoms, inclusive of any heteroatoms that occupy a ring atom position.
  • a C 3 heterocyclyl is aziridinyl.
  • Heterocycles may also be mono-, bi-, or other multi-cyclic ring systems.
  • a heterocycle may be fused to one or more aryl, partially unsaturated, or saturated rings.
  • Heterocyclyl groups include, for example, biotinyl, chromenyl, dihydrofuryl, dihydroindolyl, dihydropyranyl, dihydrothienyl, dithiazolyl, homopiperidinyl, imidazolidinyl, isoquinolyl, isothiazolidinyl, isoxazolidinyl, morpholinyl, oxolanyl, oxazolidinyl, phenoxanthenyl, piperazinyl, piperidinyl, pyranyl, pyrazolidinyl, pyrazolinyl, pyridyl, pyrimidinyl, pyrrolidinyl, pyrrolidin-2-onyl, pyrrolinyl
  • the heterocyclic ring is optionally substituted at one or more positions with substituents such as alkanoyl, alkoxy, alkyl, alkenyl, alkynyl, amido, amidino, amino, aryl, arylalkyl, azido, carbamate, carbonate, carboxy, cyano, cycloalkyl, ester, ether, formyl, halogen, haloalkyl, heteroaryl, heterocyclyl, hydroxyl, imino, ketone, nitro, phosphate, phosphonato, phosphinato, sulfate, sulfide, sulfonamido, sulfonyl and thiocarbonyl.
  • substituents such as alkanoyl, alkoxy, alkyl, alkenyl, alkynyl, amido, amidino, amino, aryl, arylalkyl, azido, carbamate, carbonate, carb
  • the heterocyclcyl group is not substituted, i.e., it is unsubstituted.
  • amine and “amino” are art-recognized and refer to both unsubstituted and substituted amines, e.g., a moiety represented by the general formula –N(R 50 )(R 51 ), wherein R 50 and R 51 each independently represent hydrogen, alkyl, cycloalkyl, heterocyclyl, alkenyl, aryl, aralkyl, or -(CH 2 )m-R 61 ; or R 50 and R 51 , taken together with the N atom to which they are attached complete a heterocycle having from 4 to 8 atoms in the ring structure; R 61 represents an aryl, a cycloalkyl, a cycloalkenyl, a heterocycle or a polycycle; and m is zero or an integer in the range of 1 to 8.
  • R 50 and R 51 each independently represent hydrogen, alkyl, alkenyl, or -(CH 2 ) m -R 61 .
  • alkoxyl or “alkoxy” are art-recognized and refer to an alkyl group, as defined above, having an oxygen radical attached thereto. Representative alkoxyl groups include methoxy, ethoxy, propyloxy, tert-butoxy and the like.
  • An “ether” is two hydrocarbons covalently linked by an oxygen.
  • the substituent of an alkyl that renders that alkyl an ether is or resembles an alkoxyl, such as may be represented by one of -O-alkyl, -O- alkenyl, -O-alkynyl, -O-(CH 2 ) m -R 61 , where m and R 61 are described above.
  • amide or “amido” as used herein refers to a radical of the form -R a C(O)N(R b )-, -R a C(O)N(R b )R c -, -C(O)NR b R c , or -C(O)NH 2 , wherein R a, R b and R c are each independently alkoxy, alkyl, alkenyl, alkynyl, amide, amino, aryl, arylalkyl, carbamate, cycloalkyl, ester, ether, formyl, halogen, haloalkyl, heteroaryl, heterocyclyl, hydrogen, hydroxyl, ketone, or nitro.
  • the amide can be attached to another group through the carbon, the nitrogen, R b , R c , or R a .
  • the amide also may be cyclic, for example R b and R c , R a and R b , or R a and R c may be joined to form a 3- to 12-membered ring, such as a 3- to 10-membered ring or a 5- to 6- membered ring.
  • the compounds of the disclosure may contain one or more chiral centers and/or double bonds and, therefore, exist as stereoisomers, such as geometric isomers, enantiomers or diastereomers.
  • stereoisomers when used herein consist of all geometric isomers, enantiomers or diastereomers. These compounds may be designated by the symbols “R” or “S,” depending on the configuration of substituents around the stereogenic carbon atom.
  • Stereoisomers include enantiomers and diastereomers. Mixtures of enantiomers or diastereomers may be designated “( ⁇ )” in nomenclature, but the skilled artisan will recognize that a structure may denote a chiral center implicitly. It is understood that graphical depictions of chemical structures, e.g., generic chemical structures, encompass all stereoisomeric forms of the specified compounds, unless indicated otherwise.
  • the terms “subject” and “patient” refer to organisms to be treated by the methods of the present invention.
  • such organisms are mammals (e.g., murines, simians, equines, bovines, porcines, canines, felines, and the like), and in some embodiments, such organisms are humans.
  • the term “effective amount” refers to the amount of a compound, composition, or formulation (e.g., a compound, composition, or formulation of the present invention) sufficient to effect beneficial or desired results.
  • the term “treating” includes any effect, e.g., lessening, reducing, modulating, ameliorating or eliminating, that results in the improvement of the condition, disease, disorder, and the like, or ameliorating a symptom thereof.
  • the terms “pharmaceutical agent,” “pharmaceutically active agent,” and “drug” are used synonymously and refer to an active agent, making the composition or formulation especially suitable for diagnostic or therapeutic use in vivo or ex vivo.
  • the term “pharmaceutically acceptable carrier” refers to any of the standard pharmaceutical carriers, such as a phosphate buffered saline solution, water, emulsions (e.g., such as an oil/water or water/oil emulsions), and various types of wetting agents.
  • the pharmaceutically acceptable carrier is, or comprises, balanced salt solution.
  • the compositions or formulations also can include stabilizers and preservatives.
  • stabilizers and adjuvants/excipients see, e.g., Martin, Remington’s Pharmaceutical Sciences, 15th Ed., Mack Publ. Co., Easton, PA [1975], the disclosure of which is incorporated by reference herein in its entirety.
  • compositions or formulations may optionally contain a dye. Accordingly, in certain embodiments, the composition or formulation further comprises a dye.
  • the molecular weight of a polymer is weight-average molecular weight unless the context clearly indicates otherwise, such as clearly indicating that the molecular weight of the polymer is the number-average molecular weight.
  • compositions or formulations and kits are described as having, including, or comprising specific components, or where processes and methods are described as having, including, or comprising specific steps, it is contemplated that, additionally, there are compositions or formulations and kits of the present invention that consist essentially of, or consist of, the recited components, and that there are processes and methods according to the present invention that consist essentially of, or consist of, the recited processing steps.
  • compositions or formulations specifying a percentage are by weight unless otherwise specified. Further, if a variable is not accompanied by a definition, then the previous definition of the variable controls.
  • One aspect of the invention provides an injectable formulation for forming an extended-release hydrogel and delivering a pharmaceutical agent over an extended period of time at the site of interest of a subject, the formulation comprising: (a) a nucleo-functional polymer that is a biocompatible polymer containing a plurality of thio-functional groups -R 1 -SH wherein R 1 is an ester-containing linker; (b) an electro-functional polymer that is a biocompatible polymer containing at least one thiol-reactive group; (c) a pharmaceutical agent; and (d) a liquid pharmaceutically acceptable carrier for administration to the eye of a subject.
  • the formulation can be further characterized by, for example, the identity and structure of the nucleo-functional polymer, the identity and structure of the electro-functional polymer, the identity of the pharmaceutical agent, physical characteristics of the hydrogel formed for controlling the delivery of the pharmaceutical agent, and other features described herein below.
  • the site of interest of the subject is the eye and the formulation is an ocular formulation.
  • the extended-release hydrogel is formed by reaction of the nucleo-functional polymer and electro-functional polymer, and the subsequent uptake of water from the subject (e.g., the subject’s eye or other tissue of interest).
  • the hydrogel is formed by a cross-linking reaction of thiolated poly(vinyl alcohol) (TPVA) with poly(ethylene glycol) (PEG) containing thiol-reactive groups.
  • the thiolated poly(vinyl alcohol) polymer can be prepared whereby thiol groups are incorporated into poly(vinyl alcohol) (PVA) by coupling thiol functionalities to the hydroxyl groups of the poly(vinyl alcohol), or through use of protected thiol functionalities with subsequent deprotection as described in the literature.
  • Certain poly(ethylene glycol) polymers containing thiol-reactive groups e.g., an acrylate, methacrylate, maleimidyl, or vinyl-sulfone may be used in accordance with the invention.
  • nucleo-functional polymer is a biocompatible polymer comprising poly(vinyl alcohol) containing a plurality of thio-functional groups -R 1 -SH where, R 1 is an ester-containing linker.
  • the nucleo-functional polymer is a biocompatible, partially hydrolyzed poly(vinyl alcohol) polymer substituted by a plurality of thio-functional groups -R 1 - SH. In certain embodiments, the nucleo-functional polymer is a biocompatible, partially hydrolyzed poly(vinyl alcohol) polymer substituted by a plurality of thio-functional groups -R 1 - SH, wherein the degree of hydrolysis of the partially hydrolyzed poly(vinyl alcohol) polymer is at least 85%. In certain embodiments, the thio-functional group -R 1 -SH is -OC(O)-(C 1 -C 6 alkylene)-SH.
  • the thio-functional group -R 1 -SH is -OC(O)-(CH 2 CH 2 )- SH.
  • the nucleo-functional polymer is a biocompatible poly(vinyl alcohol) polymer comprising: wherein a is an integer from 1 to about 20 and b is an integer from 1 to about 20.
  • the nucleo-functional polymer is a biocompatible poly(vinyl alcohol) polymer comprising: wherein a is an integer from 1 to about 20, b is an integer from 1 to about 20, and c is an integer from about 20 to about 500.
  • the nucleo-functional polymer may be further characterized according to its molecular weight, such as the weight-average molecular weight of the polymer.
  • the nucleo-functional polymer has a weight-average molecular weight in the range of from about 4,000 g/mol to about 100,000 g/mol.
  • the nucleo- functional polymer has a weight-average molecular weight less than about 75,000 g/mol.
  • the nucleo-functional polymer has a weight-average molecular weight in the range of from about 15,000 g/mol to about 25,000 g/mol.
  • the nucleo-functional polymer has a weight-average molecular weight of about 19,000 g/mol.
  • the nucleo-functional polymer is a thiolated poly(vinyl alcohol) that has been at least partially hydrolyzed (e.g., hydrolysis of about 75% or more, including all values and ranges from about 75% to about 99.9%).
  • the thiolated poly(vinyl alcohol) may be provided in a solution, dissolved in water or other solvents (including, but not limited to, dimethyl sulfoxide (DMSO) or dimethylformamide (DMF)) at any viable concentration, including at a concentration in the range of about 0.5 wt % to about 25 wt %, including all values and increments therein.
  • DMSO dimethyl sulfoxide
  • DMF dimethylformamide
  • the thiolated poly(vinyl alcohol) can be prepared by reacting a range of thiol containing functional groups with poly(vinyl alcohol), for example, as further described in U.S. Patent Application Publication No.2016/0009872, which is hereby incorporated by reference herein in its entirety.
  • thiolated poly(vinyl alcohol) is prepared by reacting (a) a compound having a thiol functionality and at least one hydroxyl-reactive group, such as, for example, a carboxyl group, represented by HS-R-CO 2 H, where R may include an alkane, unsaturated ether, or ester group, and R includes from 1 to about 20 carbons, with (b) a poly(vinyl alcohol).
  • the thiolated poly(vinyl alcohol) comprises the following fragment: wherein R includes from 1 to about 20 carbons and may be an alkane, saturated ether or ester, and the individual units are randomly distributed along the length of the poly(vinyl alcohol) chain.
  • X is in the range of about 0.1 to about 10%
  • n is in the range of about 80 to about 99.9%, indicating the level of hydrolysis of the poly(vinyl alcohol) polymer and allowing for water solubility of the polymer and m, the amount of non-hydrolyzed acetate groups, is in the range from about 0.1 to about 20%.
  • the amount of thiol groups on the poly(vinyl alcohol) can be controlled by the number of hydroxyl groups on the poly(vinyl alcohol) that undergo reaction with the thiolating agent to generate the thiolated poly(vinyl alcohol).
  • the amount of thiol functional groups on the poly(vinyl alcohol) may be characterized according to the molar ratio of thiol functional groups to poly(vinyl alcohol) polymer, such as from about 0.1:1 to about 10.0:1, including all values and ranges therein. In certain embodiments, the amount of thiol functional groups is from about 5.0:1 to about 7.0:1, including all values and ranges therein.
  • the nucleo-functional polymer containing a plurality of thio- functional groups can be prepared based on procedures described in the literature, such as U.S.
  • compositions or formulations for forming an extended-release hydrogel for extended-release of a drug for treatment of various disorders, including ocular disorders, can be characterized according to the features of the electro-functional polymer. Accordingly, in certain embodiments, the electro-functional polymer is a biocompatible poly(ethylene glycol) polymer substituted by at least one thiol-reactive group.
  • the thiol-reactive group is an alpha-beta unsaturated ester, maleimidyl, or sulfone, each of which is optionally substituted by one or more occurrences of alkyl, aryl, or aralkyl.
  • the thiol-reactive group is an alpha-beta unsaturated ester optionally substituted by one or more occurrences of alkyl, aryl, or aralkyl.
  • the thiol-reactive group is acrylate
  • the thiol-reactive group is maleimide .
  • the thiol- reactive group is vinyl sulfone .
  • the electro-functional polymer may be further characterized according to its molecular weight, such as the weight-average molecular weight of the polymer. Accordingly, in certain embodiments, the electro-functional polymer has a weight-average molecular weight in the range of from about 500 g/mol to about 100,000 g/mol. In certain embodiments, the electro- functional polymer has a weight-average molecular weight in the range of from about 1,000 g/mol to about 50,000 g/mol. In certain embodiments, the electro-functional polymer has a weight-average molecular weight in the range of from about 2,000 g/mol to about 20,000 g/mol.
  • the electro-functional polymer has a weight-average molecular weight less than about 100,000 g/mol. In certain embodiments, the electro-functional polymer has a weight-average molecular weight in the range of from about 2,700 g/mol to about 3,300 g/mol. In certain embodiments, the electro-functional polymer has a weight-average molecular weight in the range of from about 9,000 g/mol to about 11,000 g/mol. In certain embodiments, the electro-functional polymer has a weight-average molecular weight in the range of from about 18,000 g/mol to about 22,000 g/mol. [0059] The electro-functional polymer may be a straight-chain polymer or a branched chain polymer.
  • the electro-functional polymer may be a multi-arm polymer, such as 4-arm polyethylene glycol maleimide, 4-arm polyethylene glycol acrylate, 4-arm polyethylene glycol vinyl sulfone, 8-arm polyethylene glycol maleimide, 8-arm polyethylene glycol acrylate, or 8-arm polyethylene glycol vinyl sulfone or combinations thereof.
  • the electro-functional polymer may be a poly(ethylene glycol) end-capped with at least two thiol-reactive groups.
  • the poly(ethylene glycol) may be linear, branched, a dendrimer, or multi-armed.
  • the thiol reactive group may be, for example, an acrylate, methacrylate, maleimidyl, vinyl sulfone, haloacetyl, pyridyldithiol, N- hydroxysuccinimidyl.
  • An exemplary poly(ethylene glycol) end-capped with thiol-reactive groups may be represented by the formula Y-[-O-CH 2 CH 2 -] n -O-Y wherein each Y is a thiol- reactive group, and n is, for example, in the range of about 200 to about 20,000.
  • the poly(ethylene glycol) may be a dendrimer.
  • the poly(ethylene glycol) may be a 4 to 32 hydroxyl dendron.
  • the poly(ethylene glycol) may be multi-armed. In such embodiments, the poly(ethylene glycol) may be, for example, 4, 6 or 8 arm and hydroxy-terminated.
  • the molecular weight of the poly(ethylene glycol) may be varied, and in some cases one of the thiol- reactive groups may be replaced with other structures to form dangling chains, rather than crosslinks.
  • the molecular weight (Mw) is less than about 25,000, including all values and ranges from about 200 to about 20,000, such as about 200 to about 1,000, about 1,000 to about 10,000, etc.
  • the degree of functionality may be varied, meaning that the poly(ethylene glycol) may be mono-functional, di-functional or multi- functional.
  • the electro-functional polymer can be purchased from commercial sources or prepared based on procedures described in the literature, such as by treating a nucleo- functional polymer with reagent(s) to install one or more electrophilic groups (e.g., by reacting polyethylene glycol with acrylic acid in an esterification reaction to form polyethylene glycol diacrylate, using procedures described in U.S. Pat. No.6,828,401, which is incorporated by reference herein in its entirety, to form polyethylene glycol-maleimide, and using methods described in Lutolf, et al., “Synthetic matrix metalloproteinase-sensitive hydrogels for the conduction of tissue regeneration: engineering cell-invasion characteristics,” Proc. Natl. Acad.
  • compositions or formulations for forming an extended-release hydrogel for extended-release of a drug for treatment of various disorders, including ocular disorders, can be characterized according to the relative amount of nucleo-functional polymer and electro- functional polymer used.
  • the mole ratio of (i) thio- functional groups -R 1 -SH to (ii) thiol-reactive group is in the range of about 10:1 to about 1:10. In certain embodiments, the mole ratio of (i) thio-functional groups -R 1 -SH to (ii) thiol-reactive groups is in the range of about 2:1 to about 1:2. In some embodiments the mole ratio of (i) thio- functional groups -R 1 -SH to (ii) thiol-reactive groups is in the range of about 0.8:1 to about 1.2:1.
  • the combination of the nucleo-functional polymer and the electro- functional polymer in certain embodiments are present in solution in the range of about 25 mg/mL to about 150 mg/mL, including all values and ranges therein, and in some embodiments are present in solution in the range of about 25 mg/mL to about 100 mg/mL, and in certain embodiments about 90 mg/mL.
  • the Extended-Release Hydrogel System Administration of the Formulations to Form an Extended-Release Hydrogel [0064]
  • the compositions or formulations for forming an extended-release hydrogel for extended-release of a drug for treatment of various disorders, including ocular disorders, can be characterized according to the features of administration.
  • the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered through topical, epidermal, subdermal, intra-adipose, intramuscular, intra- peritoneal, intravenous, intra-arterial, intracranial, intranasal, and/or intrauterine administration.
  • the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered through injection.
  • the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered to any site of a subject where it is desired and appropriate to provide an extended-release hydrogel.
  • the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered to the eye of a subject (e.g., by injection). In some embodiments, the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered into the air-filled void within the posterior cavity of the eye of a subject following a vitrectomy. In certain embodiments, the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered in a manner as to fill or partially fill the air-filled void remaining in the eye of a subject following a complete or partial vitrectomy. In either case the amount of formulation that is delivered could be, for example, in a range between about 1 mL to about 6 mL, including all values and ranges therein.
  • the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered as a single formulation (e.g., the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent are mixed prior to administration).
  • the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered as two or more separate formulations that can mix at the target site of the subject to form the hydrogel.
  • the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered as two or more separate formulations that mix within the delivery device to form the extended-release hydrogel as the mixture exits the device.
  • the pharmaceutical agent is included in a formulation comprising the nucleo-functional polymer prior to administration. In certain embodiment the pharmaceutical agent is included in a formulation comprising the electro-functional polymer prior to administration. In certain embodiment the pharmaceutical agent is included in a formulation comprising the electro- functional polymer and in a formulation comprising the nucleo-functional polymer prior to administration. In certain embodiments, the pharmaceutical agent is included in a formulation comprising both the nucleo-functional polymer and the electro-functional polymer prior to administration.
  • Hydrogels to be used in various sites of a subject, for example in the eye, for extended release of drugs may require that the hydrogel be optically clear with transparency of at least about 80% for light in the visible spectrum when measured through a hydrogel having a thickness of 2 cm.
  • the hydrogel has a transparency of at least about 85% for light in the visible spectrum when measured through hydrogel having a thickness of 2 cm.
  • the hydrogel has a transparency of at least about 90% for light in the visible spectrum when measured through hydrogel having a thickness of 2 cm.
  • the size of the particles in the hydrogel must be less than about the wavelength of visible light, therefore in certain embodiments the size of any particle form of a pharmaceutical agent in the hydrogel should be less than about 400 nm. In certain embodiments, the size of the particle form of a pharmaceutical agent in the hydrogel is between about 25 nm and about 200 nm including all ranges therein. In some embodiments the size is between about 50 nm and about 100 nm. [0068] For use in the eye it is important to ensure adequate transmittance, for example, greater than about 80%, and the concentration of pharmaceutical agent particles and their size can impact transmittance.
  • the concentration of 50 nM pharmaceutical agent particles is between about 0.025% and about 0.001%, including all ranges therein.
  • Crosslink Time of the Polymers to Form the Extended-Release Hydrogel [0069]
  • the compositions or formulations for delivery of an extended-release hydrogel to a target site of a subject, for example the eye, can be characterized by the crosslink time of the polymers in the formulation (i.e., how long it takes for the hydrogel to form once the nucleo- functional polymer has been combined with the electro-functional polymer).
  • crosslink time should be less than about 10 minutes so that the patient does not need to remain in the surgical position for too long after administration.
  • the crosslink time of the disclosed extended-release hydrogels is less than about 7 minutes, when measured at 37°C, and in some embodiments is less than about 5 minutes, when measured at 37°C. In certain embodiments, the crosslink time of the disclosed extended-release hydrogels is less than about 3 minutes, when measured at 37°C, and in some embodiments is less than about 1 minute.
  • Administration of the Formulation to the Eye [0070] The compositions or formulations for forming an extended-release hydrogel for treatment of ocular disorders can be further characterized according to the features of administration.
  • the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered as an injection into the eye (e.g., the vitreous) without performing a vitrectomy.
  • the nucleo- functional polymer, electro-functional polymer and pharmaceutical agent may be administered as an intravitreal injection.
  • the amount of formulation that is delivered in certain embodiments is between about 25 ⁇ L to about 500 ⁇ L, including all values and ranges therein and in certain embodiments between about 50 ⁇ L and 200 ⁇ L.
  • the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered as a single formulation to the eye.
  • the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered as two or more separate formulations that can mix at the target site (e.g., the vitreous cavity of the eye) to form the extended-release hydrogel.
  • the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered as two or more separate formulations that mix within the delivery device to form the extended-release hydrogel as the mixture exits the device.
  • the two separate formulations combine and mix within the injection cannula of a delivery device.
  • the injection cannula device may have a mixing chamber that tapers into a small gauge needle that allows for entry into the eye.
  • the pharmaceutical agent is included in a formulation comprising the nucleo-functional polymer prior to administration. In certain embodiment the pharmaceutical agent is included in a formulation comprising the electro- functional polymer prior to administration. In some embodiments, the pharmaceutical agent is included in a formulation comprising the nucleo-functional polymer and in a formulation comprising the electro-functional polymer prior to administration. In certain embodiments, the pharmaceutical agent is included in a formulation comprising both the nucleo-functional polymer and the electro-functional polymer prior to administration.
  • compositions or formulations for delivery to the eye can also be characterized by the crosslink time of the polymers to form the extended- release hydrogel.
  • the crosslink time of the extended-release hydrogels described herein is less than about 30 seconds after combining the nucleo-functional polymer with the electro-functional polymer, when measured at 37°C.
  • the crosslink time is less than about 20 seconds after combining the nucleo-functional polymer with the electro-functional polymer, when measured at 37°C, and in some embodiments the crosslink time is less than about 10 seconds after combining the nucleo-functional polymer with the electro-functional polymer, when measured at 37°C. In certain embodiments, the crosslink time of the hydrogels described herein is less than about 5 seconds, less than about 3 seconds, less than about 2 seconds, or less than about 1 second after combining the nucleo-functional polymer with the electro-functional polymer, when measured at 37°C.
  • a major risk with the use of products administered to the eye is the risk of a sterile inflammatory reaction due to unacceptably high levels of endotoxin.
  • endotoxin e.g., intravitreally- administered products
  • the ocular environment is particularly sensitive to endotoxins and sterile inflammatory reactions can be seen with formulations not specifically developed for intravitreal use.
  • compositions and formulations described herein comprise less than or equal to about 0.2 endotoxin units (EU)/mL, a limit even lower than ISO standards 15798 & 11979-8 which recommend no more than (NMT) 0.5 EU/ml. In some embodiments, the compositions and formulations described herein comprises less than or equal to about 0.5 endotoxin units (EU)/mL.
  • EU endotoxin units
  • Intravitreal injection of normal saline has been observed to induce vacuoles in the photoreceptor outer segments and RPE cells, as well as upregulation of inflammatory mediators including TNF- ⁇ , IL- 1 ⁇ , IL-6, and VEGF.
  • PBS phosphate buffered vehicle
  • the extended-release hydrogel formed by the formulations described herein may act as a drug depot that may be used to deliver various pharmaceutical agents over an extended period of time.
  • the pharmaceutical agents that may be use in the formulations and extended- release hydrogels described herein include anti-inflammatory agents, steroids, NSAIDS, intraocular pressure lowering drugs, antibiotics, pain relievers, inhibitors of vascular endothelial growth factor (VEGF), inhibitors of abnormal vascular growth or vascular leakage, inhibitors of abnormal cell proliferation, chemotherapeutics, anti-viral drugs, gene therapy viral vectors, etc., and combinations thereof.
  • VEGF vascular endothelial growth factor
  • the pharmaceutical agents may be small molecules, proteins, DNA/RNA fragments, glycosaminoglycans, carbohydrates, nucleic acid, inorganic and organic biologically active compounds or other configurations, active portions of any of the proceeding molecules, and combinations thereof.
  • the pharmaceutical agent may be soluble or non-soluble, or combinations thereof in the pharmaceutically acceptable carrier.
  • the pharmaceutical agent may be dissolved in the composition or formulation, suspended as particles, encapsulated in particles (e.g., liposomes, amphiphilic polymer or solid polymer particles) and suspended, or dissolved or suspended in the formulation as an ionic complex (for example a protein- carbohydrate complex) and combinations thereof.
  • the formulations and/or extended-release hydrogel comprises more than one pharmaceutical agent.
  • one or more pharmaceutical agent is included in the formulation comprising the nucleo-functional polymer. In certain embodiments, one or more pharmaceutical agent is included in the formulation comprising the electro-functional polymer. In certain embodiments, one or more pharmaceutical agent is included in the formulation comprising the nucleo- functional polymer and in the formulation comprising the electro-functional polymer. In some embodiments, one or more pharmaceutical agents is included in a formulation comprising both the nucleo-functional polymer and the electro-functional polymer.
  • compositions or formulations for forming an extended-release hydrogel for extended-release of a drug for the treatment of various disorders, including ocular disorders can be further characterized according to the features of the extended-release hydrogel that control the release of the pharmaceutical agent into the local environment.
  • features of the extended-release hydrogel formulation for controlling the release of the pharmaceutical agent include: crosslink density or porosity, biodegradation rate, and a combination thereof.
  • Crosslink density or porosity of the extended-release hydrogel [0075] Following the administration of the composition or formulation comprising a nucleo- functional polymer, an electro-functional polymer and one or more pharmaceutical agents within the target site (e.g., the eye), the one or more pharmaceutical agents will diffuse out of the extended-release hydrogel into the surrounding environment.
  • the crosslink density of the resultant extended-release hydrogel acts as a barrier to the diffusion of the one or more pharmaceutical agents within the hydrogel.
  • a higher crosslink density results in a smaller pore size (i.e., distance between crosslinks). If the pore size is close to or less than the hydrodynamic radius of the pharmaceutical agent, then diffusion of the agent will be impeded and release from the hydrogel will be delayed.
  • the crosslinking density of the extended-release hydrogel can be controlled by the molecular weight of the nucleo-functional and electro-functional polymers and the number of functional groups present on each polymer. A lower molecular weight between crosslinks will yield a higher crosslinking density as compared to a higher molecular weight.
  • the nucleo-functional polymer has a weight- average molecular weight in the range of from about 4,000 g/mol to about 100,000 g/mol and the electro-functional polymer has a molecular weight in the range of from about 500 g/mol to about 100,000 g/mol.
  • the crosslinking density may also be controlled by the concentrations of the nucleo- functional polymer and the electro-functional polymer. Increasing the total concentration increases the cross-linking density as the likelihood or probability that an electro-functional group will combine with a nucleo-functional group and form a crosslink increases. Crosslink density may also be controlled by adjusting the relative amount of nucleo-functional polymer and electro-functional polymer used.
  • Degradation Rate of the Extended-Release Hydrogel [0077] The length of time over which the one or more pharmaceutical agents can be delivered within the target site (e.g., the eye) and surrounding environment is also a function of the length of time the extended-release hydrogel is present within the site, i.e., degradation rate or degradation time of the extended-release hydrogel. Degradation rate or time can be thought of as the rate or length of time it takes for the extended-release hydrogel to be completely in solution, i.e., for no solid mass to remain or be observed.
  • degradation rate or time can be measured by placing the extended-release hydrogel in a solution of PBS and assaying for the presence of the extended-release hydrogel (solid mass) over time. Degradation rate or time may also be measured at different temperatures (e.g., 37°C or 60°C) with higher temperature leading to a faster degradation rate and faster time to complete degradation.
  • the degradation time of the extended-release hydrogels described herein is greater than or equal to about 20, 40, 60, 69, 80, 90, 94, 100, 120, 140, or 158 days at 37°C. In some embodiments, the degradation time of the extended-release hydrogels described herein is greater than or equal to about 3, 5, 8, 10, 14, 19, 20, 25, 30, or 32 days at 60° C.
  • the pharmaceutical composition or formulation comprises (i) a nucleo- functional polymer; (ii) a pharmaceutical agent; and (iii) a pharmaceutically acceptable carrier for administration to the desired target site.
  • the pharmaceutical composition or formulation comprises (i) an electro-functional polymer; (ii) a pharmaceutical agent; and (iii) a pharmaceutically acceptable carrier for administration to the desired target site.
  • the pharmaceutical composition or formulation comprises (i) a nucleo- functional polymer; (ii) an electro-functional polymer; (iii) a pharmaceutical agent; and (iv) a pharmaceutically acceptable carrier for administration to the desired target site.
  • the target site is the eye of a subject.
  • the target site is the eye of a human.
  • the pharmaceutical composition or formulation is a liquid pharmaceutical composition or composition.
  • the pharmaceutical composition or formulation is a lyophilized pharmaceutical composition or formulation.
  • the pharmaceutically acceptable carrier is PBS, water, or a combination thereof.
  • the pharmaceutical composition or formulation is sterile and may optionally comprise a preservative, antioxidant, and/or other excipients.
  • excipients include, for example, acacia, agar, alginic acid, bentonite, carbomers, carboxymethylcellulose calcium, carboxymethylcellulose sodium, carrageenan, ceratonia, cetostearyl alcohol, chitosan, colloidal silicon dioxide, cyclomethicone, cyclo-dextrin, ethylcellulose, gelatin, glycerin, glyceryl behenate, guar gum, hectorite, hydrogenated vegetable oil type I, hydroxyethyl cellulose, hydroxyethylmethyl cellulose, hydroxypropyl cellulose, hydroxypropyl starch, hypromellose, hyaluronic acid, magnesium aluminum silicate, maltodextrin, methylcellulose, polydextrose, polyethylene glycol, poly(methylvinyl)
  • the excipient is a bioadhesive or comprises a bioadhesive polymer.
  • the concentration of the excipient in the pharmaceutical composition or formulation ranges from about 0.1 to about 20% by weight. In certain embodiments, the concentration of the excipient in the pharmaceutical composition or formulation ranges from about 5 to about 20% by weight.
  • the concentration of the excipient in the pharmaceutical composition or formulation is less than about 20%, less than about 15%, less than about 10%, less than about 9%, less than about 8%, less than about 7%, less than about 6%, less than about 5%), less than about 4%, less than about 3%, less than about 2%, less than about 1.8%, less than about 1.6%, less than about 1.5%, less than about 1.4%, less than about 1.2%, less than about 1%, less than about 0.9%, less than about 0.8%, less than about 0.7%, less than about 0.6%, less than about 0.5%, less than about 0.4%, less than about 0.3%, less than about 0.2%, or less than about 0.1% by weight.
  • the pharmaceutical composition or formulation may be further characterized according to its viscosity.
  • the viscosity of the pharmaceutical composition is less than about 4000 cP, less than about 2000 cP, less than about 1000 cP, less than about 800 cP, less than about 600 cP, less than about 500 cP, less than about 400 cP, less than about 200 cP, less than about 100 cP, less than about 80 cP, less than about 60 cP, less than about 50 cP, less than about 40 cP, less than about 20 cP, less than about 10 cP, less than about 8 cP, less than about 6 cP, less than about 5 cP, less than about 4 cP, less than about 3 cP, less than about 2 cP, less than about 1 cP.
  • the viscosity of the pharmaceutical composition or formulation is at least about 4,000 cP, at least about 2,000 cP, at least about 1,000 cP, at least about 800 cP, at least about 600 cP, at least about 500 cP, at least about 400 cP, at least about 200 cP, at least about 100 cP, at least about 80 cP, at least about 60 cP, at least about 50 cP, at least about 40 cP, at least about 20 cP, at least about 10 cP, at least about 8 cP, at least about 6 cP, at least about 5 cP, at least about 4 cP, at least about 3 cP, at least about 2 cP, at least about 1 cP.
  • the viscosity of the pharmaceutical composition or formulation is about 4,000 cP, about 2,000 cP, about 1,000 cP, about 800 cP, about 600 cP, about 500 cP, about 400 cP, about 200 cP, about 100 cP, about 80 cP, about 60 cP, about 50 cP, about 40 cP, about 20 cP, about 10 cP, about 8 cP, about 6 cP, about 5 cP, about 4 cP, about 3 cP, about 2 cP, about 1 cP. In some embodiments, the viscosity of the pharmaceutical composition or formulation is between about 5 cP and about 50 cP.
  • the pharmaceutical composition or formulation may be further characterized according to its pH.
  • the pharmaceutical composition or formulation has a pH in the range of from about 5 to about 9, or about 6 to about 8.
  • the pharmaceutical composition or formulation has a pH in the range of from about 6.5 to about 7.5.
  • the pharmaceutical composition or formulation has a pH of about 7.
  • the pharmaceutical composition or formulation comprises water, and the composition or formulation has a pH in the range of about 7.1 to about 7.7.
  • the pharmaceutical composition or formulation comprises water, and the composition or formulation has a pH in the range of about 7.1 to about 7.6, about 7.1 to about 7.5, about 7.1 to about 7.4, about 7.2 to about 7.6, about 7.2 to about 7.5, about 7.2 to about 7.4, about 7.2 to about 7.3, about 7.3 to about 7.7, about 7.3 to about 7.6, about 7.3 to about 7.5, about 7.3 to about 7.4, about 7.4 to about 7.7, about 7.4 to about 7.6, or about 7.4 to about 7.5.
  • the pharmaceutical composition or formulation comprises water, and the composition or formulation has a pH in the range of about 7.3 to about 7.5.
  • the pharmaceutical composition or formulation comprises water, and the composition or formulation has a pH of about 7.4.
  • the pharmaceutical composition or formulation may be further characterized according to its osmolality and the presence and/or identity of salts.
  • the pharmaceutical composition or formulation has an osmolality in the range of about 200 mOsm / kg to about 400 mOsm / kg.
  • the pharmaceutical composition or formulation has an osmolality in the range of about 250 mOsm / kg to about 350 mOsm / kg.
  • the pharmaceutical composition or formulation has an osmolality in the range of about 280 mOsm / kg to about 320 mOsm / kg.
  • the pharmaceutical composition or formulation has an osmolality of about 300 mOsm / kg.
  • the pharmaceutical composition or formulation further comprises an alkali metal salt.
  • the pharmaceutical composition or formulation further comprises an alkali metal halide salt, an alkaline earth metal halide salt, or a combination thereof.
  • the pharmaceutical composition or formulation further comprises sodium chloride.
  • the pharmaceutical composition or formulation further comprises sodium chloride, potassium chloride, calcium chloride, magnesium chloride, or a combination of two or more of the foregoing.
  • the pharmaceutical composition or formulation comprises phosphate buffered saline (PBS).
  • PBS phosphate buffered saline
  • the PBS comprises one or more of sodium chloride, potassium chloride, sodium phosphate and potassium phosphate.
  • the pharmaceutical composition or formulation may be further characterized according to the level of endotoxins present in the composition or formulation.
  • the composition or formulation has an endotoxin level of less than about 20 endotoxin units/ml, less than about 15 endotoxin units/ml, less than about 10 endotoxin units/ml, less than about 5 endotoxin units/ml, less than about 2.5 endotoxin units/ml, less than about 1.0 endotoxin units/ml, less than about 0.8 endotoxin units/ml, less than about 0.5 endotoxin units/ml, less than about 0.2 endotoxin units/ml, or less than about 0.1 endotoxin units/ml.
  • the pharmaceutical composition or formulation may also be characterized by the size and number of any particles, including any drug particles, present in the composition or formulation.
  • the composition or formulation has less than about 50 particles per mL with a size of ⁇ 10 ⁇ m. In some embodiments, the composition or formulation has less than about 5 particles per mL with a size of ⁇ 25 ⁇ m.
  • KITS FOR USE IN MEDICAL APPLICATIONS [0087] Another aspect of the invention provides a kit for treating a disorder.
  • the kit comprises: i) a formulation comprising a nucleo-functional polymer and a pharmaceutical agent and ii) a formulation comprising an electro-functional polymer.
  • the kit comprises: i) a formulation comprising a nucleo-functional polymer and ii) a formulation comprising an electro-functional polymer and a pharmaceutical agent. In some embodiments, the kit comprises: i) a formulation comprising a nucleo-functional polymer and a pharmaceutical agent and ii) a formulation comprising an electro-functional polymer and a pharmaceutical agent. In certain embodiments, the kit comprises: i) a formulation comprising a nucleo-functional polymer; ii) a formulation comprising a pharmaceutical agent, and iii) a formulation comprising an electro-functional polymer. In some embodiments one or more the formulations provided in the kit comprises a pharmaceutically acceptable carrier.
  • the pharmaceutically acceptable carrier comprises PBS.
  • the kit further comprises instructions for administering the formulations to a target site of interest in a subject, for example, the eye of a subject.
  • the kit further comprises the components and/or accessories required to prepare and administer the formulations to a target site of interest in a subject, for example the eye of a subject.
  • Hydrogels were prepared from formulations that resulted from combining thiolated poly(vinyl alcohol) (tPVA), with polyethylene glycol polymers having varying thiol-reactive groups and structures.
  • tPVA thiolated poly(vinyl alcohol)
  • PBS phosphate buffered saline
  • Equal volumes of the tPVA and PEG solutions were combined into a formulation and allowed to react at ambient temperatures (20-22°C).
  • Crosslink time of the polymers was measured by the time required for a 1.9 mm x 8 mm magnetic stir bar spinning at 100 rpm immersed within the formulation to stop spinning.
  • Degradation time of the hydrogel was determined by placing 1 mg hydrogel samples in 10 mL of PBS at either 60°C or 37°C. Samples were observed and PBS was changed daily. Degradation time was defined as the day that the hydrogel sample was completely in solution, i.e., no solid mass was observed. Results are summarized in Table 1A. Table 1A.
  • Hydrogels were prepared by combining a formulation comprising thiolated poly (vinyl alcohol) (tPVA) with formulations comprising polyethylene glycol polymers having varying thiol-reactive groups and structures.
  • tPVA thiolated poly
  • PBS phosphate buffered saline
  • the pore size of the extended-release hydrogel should be close to or smaller than the hydrodynamic radius of the molecule.
  • the pore size of the hydrogel is determined by the distance between crosslinks or the crosslink density; the higher the crosslink density, the smaller the pore size.
  • the pore size of a hydrogel can be evaluated by measuring the diffusion of dextran having varying hydrodynamic radii within the hydrogel.
  • Hydrogels were prepared from a formulation comprising thiolated poly(vinyl alcohol) (tPVA) and polyethylene glycol acrylate polymers having varying molecular weights and structures (i.e., single and multi-arm).
  • tPVA and PEG-acrylate polymers were separately dissolved in phosphate buffered saline (PBS) at varying concentrations.
  • PBS phosphate buffered saline
  • Equal volumes of the tPVA and PEG-acrylate solutions were combined into a formulation and allowed to react at ambient temperatures (20-22°C).
  • the amount of fluorescently labeled Dextran released from the hydrogels over 24 hours was determined. (Liao, et.
  • Dextrans (Molecular weight 20 kDa, 40 kDa, 75 kDa and 150 kDa) labeled with fluorescein isothiocyanate (FITC-Dextran) were dissolved in water at 10 mg/mL. Hydrogel samples were placed in test tubes and a FITC-Dextran solution was added to the tubes. The FITC-Dextran was allowed to diffuse into the hydrogels for 24 hours at 37°C.
  • the amount of diffused FITC-Dextran is lowest for the hydrogel formed using the 1:1 ratio of 6% tPVA:12% 4-arm PEG Acrylate formulation. Therefore, this formulation has the smallest hydrogel pore size of those shown in Table 2.
  • EXAMPLE 3 - FITC-DEXTRAN INCORPORATION AND RELEASE FROM HYDROGELS Hydrogels were prepared from formulations comprising thiolated poly(vinyl alcohol) (tPVA) and polyethylene glycol polymers having varying thiol-reactive groups and structures. tPVA was dissolved in 1 mL phosphate buffered saline (PBS) at a concentration of 6%.
  • PBS phosphate buffered saline
  • FITC- Dextran (70 kDa) was dissolved in 1 mL PBS at a concentration of 22.5 mg/mL.
  • the PEG-thiol reactive polymer was dissolved in the FITC-Dextran/PBS solution at a concentration of 12%.
  • Equal 1 mL volumes of the tPVA and PEG/Dextran solutions were combined and allowed to react at ambient temperatures (20-22° C).
  • a 1.2 g sample of each Dextran-loaded hydrogel ( ⁇ 13.5 mg FITC Dextran/sample) was placed in a dialysis tube. 2 mL of PBS was added to the inside of the tube and the tube placed in a container with 30 mL of PBS.
  • FITC-Dextran (70 kDa) was dissolved in 1 mL PBS at a concentration of 22.5 mg/mL.
  • the 4-arm PEG maleimide polymer was dissolved in the FITC-Dextran/PBS solution at a concentration of 12%.
  • Equal 1 mL volumes of the tPVA and PEG/Dextran solutions were placed in separate barrels of a dual barrel syringe.
  • a mixing tip was attached to the end of the dual barrel syringe and the two solutions were injected through the mixing tip simultaneously.
  • the polymers crosslinked as they combined within the mixing tip (i.e., within seconds) forming a firm hydrogel exiting the mixing tip.
  • a 1.2 g sample of each Dextran-loaded hydrogel was placed in a dialysis tube. 2 mL of PBS was added to the inside of the tube and the tube placed in a container with 30 mL of PBS. Containers were placed in an incubator at 37°C. The PBS in the container was sampled periodically and its fluorescence measured to determine the amount of FITC-Dextran released from the hydrogel. The PBS in the container was replaced after sampling to ensure sink conditions were maintained throughout the study. [0100] The results of the release study are shown in Figure 2 as cumulative % release vs. days 1/2 . The results show a nearly first-order release of the 70 kDa FITC-Dextran from the hydrogel over > 60 days.
  • Bevacizumab is an anti-VEGF monoclonal antibody (large protein) with a molecular weight of ⁇ 150kD that has been found to be a very effective treatment for several back-of-the- eye diseases including age-related macular degeneration (AMD), proliferative diabetic retinopathy, diabetic macular edema, macular edema from retinal vein occlusions and choroidal neovascularization, among others.
  • AMD age-related macular degeneration
  • Intravitreal injection of bevacizumab at a dose of 1.25mg has been well tolerated and shown to provide improvement in visual acuity, decreased retinal thickness and reduction in vascular leakage in many patients.
  • monthly repetitive injections are required to maintain the effective dose of ⁇ 1 ⁇ g/mL in the vitreous.
  • endophthalmitis As well as the pain, apprehension and distress associated with inserting needles into eyes. Therefore a delivery method that reduces the need for repetitive injections and extends the therapeutic dose in the vitreous would provide a significant improvement.
  • Bevacizumab was loaded into tPVA:4-arm PEG vinyl sulfone (PEG-4VS-1, PEG- 4VS-2) and tPVA:4-arm PEG maleimide (PEG-4MAL) hydrogels as described in Examples 3 and 4, respectively. Release studies were performed as described previously. 0.5 g samples with ⁇ 6mg bevacizumab were loaded into the dialysis tubes.1 mL of PBS was added to the tubes and the tubes were placed in a container with 30 mL of PBS at 37° C. The amount of bevacizumab released at each time point was determined by measuring the auto-florescence of the protein in the release solutions at 280 nm.
  • Tacrolimus is a small molecule drug ( ⁇ 800 Da) with low solubility in water ( ⁇ 1 ⁇ g/mL). It is an anti-inflammatory drug that may be useful in treating various conditions, including uveitis or other inflammatory conditions of the eye.
  • Tacrolimus was encapsulated in Soluplus®, a graft co-polymer of polycaprolactam- polyvinyl aetate-polyethylene glycol.
  • Soluplus® is an amphiphilic polymer that self-assembles into nanomicelles in water.
  • Tacrolimus was encapsulated within the hydrophobic core of the nanomicelles as described in Wu, et. al., “Novel self-assembled tacrolimus nanoparticles cross- linking thermosensitive hydrogels for local rheumatoid arthritis therapy” Colloids and Surfaces B: Biointerfaces 14997–104 (2017). Nanoparticles with a size of 70 ⁇ 20 nm incorporating ⁇ 12% tacrolimus by weight were obtained.
  • Hydrogels were prepared from thiolated poly(vinyl alcohol) (tPVA) and polyethylene glycol diacrylate (PEGDA). tPVA was dissolved in 1 mL phosphate buffered saline (PBS) at a concentration of 6%.
  • PBS phosphate buffered saline
  • EXAMPLE 7 – BEVACIZUMAB RELEASE FROM TPVA:PEG-4MAL HYDROGEL [0108] Bevacizumab was loaded into a tPVA:PEG-4MAL hydrogel as follows. Lyophilized tPVA (30 mg) was dissolved in 0.5 mL PBS to create a 6% tPVA solution. Bevacizumab (23.6 mg/mL) was diluted to 4mg/mL in PBS. 0.5 mL of the 4 mg/mL Bevacizumab/PBS solution was added to 60 mg of PEG-4MAL to create a 12% PEG-4MAL solution.
  • Equal 0.5 mL volumes of the tPVA and PEG-4MAL/Bevacizumab solutions were placed in separate barrels of a dual barrel syringe.
  • a mixing tip was attached to the end of the dual barrel syringe and the two solutions were injected through the mixing tip simultaneously into a petri dish.
  • a 0.5 g sample of the formed hydrogel was placed in a dialysis tube.2 mL of PBS was added to the tube and the tube was placed in a container with 30 mL of PBS. The container was placed in an incubator at 37° C.
  • the PBS in the container was sampled periodically and the Bevacizumab concentration measured by ELISA to determine the amount released from the hydrogel.
  • a 6% tPVA solution was prepared by reconstituting 0.24 g lyophilized tPVA with 4 mL PBS.
  • a 12% PEG-4MAL solution was prepared by reconstituting 0.36 g PEG-4MAL with 3 mL PBS.
  • a 6% tPVA/Bevacizumab solution was prepared by reconstituting 0.24g of lyophilized tPVA with 2 mL PBS and 2 mL of Bevacizumab (23.6 mg/mL).
  • For hydrogels without Bevacizumab equal 70 ⁇ L volumes of 6% tPVA solution and 12% PEG-4MAL solution were loaded into separate 1 mL syringes.
  • the syringes were inserted in a two syringe single use dispenser connected to a luer lock adapter (M-System, Sulzer MedMix) and a 30g low dead space needle (TSK Laboratory).
  • M-System, Sulzer MedMix a luer lock adapter
  • TSK Laboratory a 30g low dead space needle
  • Bevacizumab loaded hydrogels equal 70 ⁇ L volumes of tPVA/Bevacizumab solution and PEG-4MAL solution were loaded into the delivery system.
  • the 30g needle was inserted through the sclera into the vitreous of a rabbit eye. For each injection, ⁇ 140 ⁇ L of hydrogel of the combined solution was injected directly into the vitreous.

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Abstract

Provided are formulations and methods for providing extended-release of a pharmaceutical agent from a hydrogel at a target site of a subject, wherein the extended-release hydrogel is formed from the formulations and methods of the invention. The formulations and resulting extended- release hydrogels may be used for treating various disorders, including ocular disorders. In certain embodiments, the extended-release hydrogel is formed from formulations comprising (a) a nucleo-functional polymer that is a biocompatible polyalkylene polymer substituted by (i) a plurality of -OH groups, (ii) a plurality' of thio-functional groups -R1-SH wherein R1 is an ester- containing linker, and (iii) optionally one or more -OC(O)~(C1-C6 alkyl) groups, such as a thiolated poly(vinyl alcohol) polymer; (b) an electro-functional polymer that is a biocompatible polymer containing at least one thiol-reactive group, such as a poly(ethylene glycol) polymer containing alpha-beta unsaturated ester groups; and (c) one or more pharmaceutically active agents.

Description

EXTENDED-RELEASE HYDROGEL-DRUG FORMULATIONS CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of and priority to United States Provisional Patent Application serial number 63/134,829, filed on January 7, 2021, the disclosure of which is hereby incorporated by reference in its entirety. FIELD OF THE INVENTION [0002] The invention is directed to formulations comprising polymers and polymer compositions that form extended-release hydrogels comprising a pharmaceutically active agent (e.g., a drug) and methods of using the extended-release hydrogels comprising a pharmaceutically active agent for providing targeted release of the pharmaceutically active agent to a site of interest in a subject for a variety of disorders. BACKGROUND [0003] Delivering a pharmaceutically active agent (e.g., a drug) to the body in an extended- release fashion provides many benefits to the subject, including more specific delivery, less off- site side-effects, more consistent and targeted control of drug dose over time, decreased frequency of drug administration, and better subject compliance. Importantly, a formulation for forming an extended-release hydrogel that can be injected through a cannula or needle, in particular a cannula or needle with a smaller diameter, could be directed into a wide variety of anatomical spaces, which would be clinically advantageous. For example, formulations for forming an extended-release hydrogel comprising a pharmaceutically active agent could be administered nearly anywhere in the body in a variety of ways, including but not limited to, topical, epidermal, subdermal, intra-adipose, intramuscular, intra-peritoneal, intravenous, intra- arterial, intracranial, intranasal, and/or intrauterine. In addition, targeted therapy through injection of a formulation that forms an extended-release hydrogel comprising a pharmaceutically active agent into an organ directly, the wall of an organ, or into the surrounding fascia or connective tissue of an organ would be desirable and beneficial. [0004] Targeted extended release of a pharmaceutically active agent is particularly compelling when the target tissue is difficult to access clinically, a sensitive area, and/or where repeat access is invasive or burdensome to the subject. One compelling example is the eye. The structure of the mammalian eye is divided into two segments: the anterior and posterior. The anterior segment or anterior cavity is the front third of the eye and includes the cornea, iris, ciliary body, and lens. The posterior segment or posterior cavity is the back two-thirds of the eye and includes the choroid, retina, optic nerve, and vitreous humor. There are a number of disease conditions that affect the back of the eye and impact vision, including age-related macular degeneration (AMD), proliferative diabetic retinopathy, proliferative vitreoretinopathy, ocular malignancies, inherited retinal diseases, diabetic macular edema, macular edema from retinal vein occlusions, choroidal neovascularization, uveitis, amongst others. [0005] Typical routes for administration of pharmaceutically active agents (e.g., drugs) to the eye include topical, systemic, subcutaneous, intravitreal, subretinal, intraocular, intracameral, suprachoroidal, subconjunctival, subtenon, intracanalicular, periobulbar and retrobulbar. [0006] Effective delivery of pharmaceutically active agents for treatment of back-of-the-eye diseases remains a challenge. Delivery to the posterior segment of the eye is typically achieved via an intravitreal injection, the periocular route, implant, or by systemic administration. However, physiologic barriers to transport of the pharmaceutically active agents to the posterior segment from routes other than intravitreal injection often make their use impractical. [0007] Intravitreal injection is often carried out with a 30 gauge or similar needle. While intravitreal injections offer high concentrations of pharmaceutically active agent to the vitreous chamber and retina, they can be associated with various short term complications such as retinal detachment, inflammation, elevated intraocular pressure, endophthalmitis and intravitreal hemorrhage. Injection of small particles within the vitreous may lead to wide dispersal of the particles which can obstruct vision (experienced by the patient as “floaters”). Additionally, many current formulations for administration of a pharmaceutically active agent to the eye often require frequent repeat injections (e.g., monthly), thus increasing the risk of complications and resulting in a substantial burden on both the patient and the healthcare system in general. [0008] A profound need exists for targeted extended-release pharmaceutically active agent delivery formulations, in particular, formulations that can be injected into sensitive/delicate tissues, including the eye. Formulations that provide for in-situ formation of hydrogels that provide extended-release of pharmaceutically active agents within the body can provide for longer-lasting drug delivery, minimize the risks of repeated administrations, such as injections, deliver more consistent and targeted doses, limit side effects, and decrease the substantial burden placed on the patient by repeat drug administration. SUMMARY OF THE INVENTION [0009] Polymer-pharmaceutically active agent formulations for treating clinical disorders, wherein the polymer-pharmaceutically active agent formulations form an extended-release hydrogel containing a pharmaceutically active agent in the desired tissue of a subject, are provided. The extended-release hydrogel is formed by reaction of (a) a nucleo-functional polymer that is a biocompatible polymer containing (i) plurality of -OH groups and (ii) a plurality of thio-functional groups -R1-SH wherein R1 is an ester-containing linker and (b) an electro-functional polymer that is a biocompatible polymer containing at least one thiol-reactive group, such as an alpha-beta unsaturated ester. In certain embodiments, formulations are provided comprising a nucleo-functional polymer, an electro-functional polymer and a pharmaceutically active agent in a pharmaceutically acceptable carrier. In some embodiments, formulations are provided comprising a nucleo-functional polymer and a pharmaceutically active agent in a pharmaceutically acceptable carrier. In certain embodiments, formulations are provided comprising an electro-functional polymer and a pharmaceutically active agent in a pharmaceutically acceptable carrier. In some embodiments, the nucleo-functional polymer and electro-functional polymer formulations are desirably low-viscosity solutions that can be injected easily into the target tissue of a subject through a narrow-gauge needle, thereby permitting administration of the polymers while minimizing trauma to certain sensitive structures, like injection into the subject’s eye. In certain embodiments, the nucleo-functional polymer and electro-functional polymer begin to react once mixed; the reaction between the nucleo-functional polymer and electro-functional polymer to create an extended-release hydrogel comprising a pharmaceutically active agent occurs when the polymers are mixed prior to delivery to the subject’s target site, as they are delivered to the subject’s target site, and/or within the target site of the subject thereby forming a hydrogel in situ in the target site of the subject that immobilizes the pharmaceutical agent from immediate dispersal and provides for extended-release of the pharmaceutical agent. [0010] During degradation of the extended-release hydrogel, the pharmaceutically active agent diffuses out of the hydrogel and into the local environment over a period of time, i.e., extended-release, that provides for therapeutically effective longer-term therapy than what would be achieved by injection of the pharmaceutically active agent alone. In certain embodiments the pharmaceutically active agent may be dissolved in the extended-release hydrogel-forming formulation, suspended within the extended-release hydrogel-forming formulation and/or encapsulated within a particle and dispersed within the extended-release hydrogel-forming formulation. In certain embodiments, features of the extended-release hydrogel-forming formulation and/or extended-release hydrogel include: materials that are non-toxic, varying crosslink density or porosity, varying reaction kinetics and varying biodegradation rate, all of which are appropriate to the desired method of administration, the desired target site in the subject, and the timeframe desired for the extended-release of the pharmaceutical into the environment surrounding the target site. [0011] The following embodiments recite non-limiting permutations of combinations of features of the inventions described. Other permutations of combinations of features are also contemplated and/or described throughout the disclosure. In particular, each of these numbered embodiments is contemplated as depending from or relating to every previous or subsequent numbered embodiment, independent of the listed order. [0012] E1. A formulation for forming an extended-release hydrogel, the formulation comprising: a. a nucleo-functional polymer that is a biocompatible polymer containing a plurality of thio-functional groups -R1-SH wherein R1 is an ester-containing linker; b. an electro- functional polymer that is a biocompatible polymer containing at least one thiol-reactive group; c. a pharmaceutical agent; and d. a pharmaceutically acceptable carrier. E2. The formulation of embodiment E1, wherein the nucleo-functional polymer is a biocompatible polymer comprising poly(vinyl alcohol). E3. The formulation of embodiment E1 or E2, wherein the nucleo-functional polymer comprises a biocompatible poly(vinyl alcohol) polymer substituted by a plurality of thio-functional groups -R1-SH. E4. The formulation of any of embodiments E1-E3, wherein the nucleo-functional polymer comprises a biocompatible, partially hydrolyzed poly(vinyl alcohol). E5. The formulation of embodiment E4, wherein the partially hydrolyzed poly(vinyl alcohol) polymer has a degree of hydrolysis in the range of about 75% to about 99.9%. E6. The formulation of any one of embodiments E1-E5, wherein the thio-functional group -R1-SH is - OC(O)-(C1-C6 alkylene)-SH. E7. The formulation of any one of embodiments E1-E6, wherein the thio-functional group -R1-SH is -OC(O)-(CH2CH2)-SH. E8. The formulation of embodiment 1, wherein the nucleo-functional polymer is a biocompatible poly(vinyl alcohol) polymer comprising:
Figure imgf000006_0001
wherein a is an integer from 1 to about 20 and b is an integer from 1 to about 20. E9. The formulation of embodiment 1, wherein the nucleo- functional polymer is a biocompatible poly(vinyl alcohol) polymer comprising:
Figure imgf000006_0002
wherein a is an integer from 1 to about 20, b is an integer from 1 to about 20, and c is an integer from about 20 to about 500. E10. The formulation of any one of embodiments E1-E9, wherein the nucleo-functional polymer has a weight-average molecular weight in the range of from about 4,000 g/mol to about 100,000 g/mol. E11. The formulation of any one of embodiments E1-E10, wherein the nucleo-functional polymer has a weight-average molecular weight in the range of from about 15,000 g/mol to about 25,000 g/mol. E12. The formulation of any one of embodiments E1-E9, wherein the nucleo-functional polymer has a weight-average molecular weight of less than about 75,000 g/mol. E13. The formulation of any one of embodiments E1-E12, wherein the electro-functional polymer is a biocompatible polymer comprising poly(ethylene glycol). E14. The formulation of any one of embodiments E1-E13, wherein the electro-functional polymer is a biocompatible polymer comprising poly(ethylene glycol)polymer substituted by at least one thiol-reactive group. E15. The formulation of any one of embodiments E1-E14, wherein the thiol-reactive group is an alpha-beta unsaturated ester, maleimidyl, sulfone, or combinations thereof. E16. The formulation of embodiment E15, wherein the alpha-beta unsaturated ester, maleimidyl, or sulfone is optionally substituted by one or more occurrences of alkyl, aryl, or aralkyl. E17. The formulation of any one of embodiments E1-E16, wherein the thiol-reactive group is acrylate, maleimide, or vinylsulfone. E18. The formulation of any one of embodiments E1-E17, wherein the electro- functional polymer has a weight-average molecular weight in the range of from about 500 g/mol to about 100,000 g/mol. E19. The formulation of any one of embodiments E1-E18, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 1,000 g/mol to about 50,000 g/mol. E20. The formulation of any one of embodiments E1-E19, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 2,000 g/mol to about 20,000 g/mol. E21. The formulation of any one of embodiments E1-E20, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 2,700 g/mol to about 3,000 g/mol. E22. The formulation of any one of embodiments E1-E20, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 9,000 g/mol to about 11,000 g/mol. E23. The formulation of any one of embodiments E1-E19, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 18,000 g/mol to about 22,000 g/mol. E24. The formulation of any one of embodiments E1-E23, wherein the electro-functional polymer comprises a multi-arm polymer. E25. The formulation of embodiment E24, wherein the multi- arm polymer comprises as 4-arm polyethylene glycol maleimide, 4-arm polyethylene glycol acrylate, 4-arm polyethylene glycol vinyl sulfone, 8-arm polyethylene glycol maleimide, 8-arm polyethylene glycol acrylate, 8-arm polyethylene glycol vinyl sulfone, or combinations thereof. E26. The formulation of any one of embodiments E1-E25, wherein the mole ratio of (i) thio- functional groups -R1-SH to (ii) thiol-reactive group is in the range of about 10:1 to about 1:10. E27. The formulation of any one of embodiments E1-E26, wherein the mole ratio of (i) thio- functional groups -R1-SH to (ii) thiol-reactive groups is in the range of about 2:1 to about 1:2. E28. The formulation of any one of embodiments E1-E25, wherein the mole ratio of (i) thio- functional groups -R1-SH to (ii) thiol-reactive groups is in the range of about 0.8:1 to about 1.2:1. E29. The formulation of any one of embodiments E1-E28, wherein the formulation comprises water, and the formulation has a pH in the range of about 7.1 to about 7.7. E30. The formulation of any one of embodiments E1-E28, wherein the formulation comprises water, and the formulation has a pH in the range of about 7.3 to about 7.5. E31. The formulation of any one of embodiments E1-E28, wherein the formulation comprises water, and the formulation has a pH of about 7.4. E32. The formulation of any one of embodiments E1-E31, further comprising an alkali metal salt. E33. The formulation of any one of embodiments E1-E32, further comprising an alkali metal halide salt, an alkaline earth metal halide salt, or a combination thereof. E34. The formulation of any one of embodiments E1-E33, further comprising sodium chloride, potassium chloride, calcium chloride, magnesium chloride, or a combination thereof. E35. The formulation of any one of embodiments E1-E34, wherein the formulation has an osmolality in the range of about 200 mOsm / kg to about 400 mOsm / kg. E36. The formulation of any one of embodiments E1-E35, wherein the formulation has an osmolality in the range of about 250 mOsm / kg to about 350 mOsm / kg. E37. The formulation of any one of embodiments E1-E36, wherein the formulation has an osmolality in the range of about 280 mOsm / kg to about 320 mOsm / kg. E38. The formulation of any one of embodiments E1-E37, wherein the formulation has an osmolality of about 300 mOsm / kg. E39. The formulation of any one of embodiments E1-E38, wherein the formulation has an endotoxin level of less than about 20 endotoxin units/ml, less than about 15 endotoxin units/ml, less than about 10 endotoxin units/ml, less than about 5 endotoxin units/ml, less than about 2.5 endotoxin units/ml, less than about 1.0 endotoxin units/ml, less than about 0.8 endotoxin units/ml, less than about 0.5 endotoxin units/ml, less than about 0.2 endotoxin units/ml, or less than about 0.1 endotoxin units/ml. E40. The formulation of any one of embodiments E1-E39, wherein the formulation has less than about 50 particles per mL with a size of ^ 10 μm. E41. The formulation of any one of embodiments E1-E39, wherein the formulation has less than about 5 particles per mL with a size of ^ 25 μm. E42. The formulation of any one of embodiments E1-E41, wherein the hydrogel formed by the formulation has a transparency of at least about 80% for light in the visible spectrum when measured through a hydrogel having a thickness of 2 cm. E43. The formulation of any one of embodiments E1-E42, wherein the hydrogel formed by the formulation has a transparency of at least about 85% for light in the visible spectrum when measured through a hydrogel having a thickness of 2 cm. E44. The formulation of any one of embodiments E1-E43, wherein the hydrogel formed by the formulation has a transparency or at least about 90% for light in the visible spectrum when measured through a hydrogel having a thickness of 2 cm. E45. The formulation of any one of embodiments E1-E44, wherein the hydrogel formed by the formulation has a crosslink time of less than about 10 minutes, less than about 7 minutes, less than about 5 minutes, less than about 3 minutes, less than about 1 minute, less than about 20 seconds, less than about 10 seconds, less than about 5 seconds, or less than about 1 second when measured at 37°C. E46. The formulation of any one of embodiments E1-E45, wherein the hydrogel formed by the formulation has a degradation time that is greater than or equal to about 3, about 5, about 8, about 10, about 13, about 14, about 15, about 19, or about 32 days at 60°C. E47. The formulation of any one of embodiments E1-E45, wherein the hydrogel formed by the formulation has a degradation time that is greater than or equal to about 20, about 40, about 60, about 69, about 80, about 94, about 100, or about 158 days at 37°C. E48. The formulation of any one of embodiments E1-E47, wherein the hydrogel formed by the formulation acts as a depot for the pharmaceutical agent. E49. The formulation of any one of embodiments E1-E48, wherein the hydrogel formed by the formulation provides for extended-release of the pharmaceutical agent. E50. The formulation of any one of embodiments E1-E49, wherein the hydrogel formed by the formulation releases the pharmaceutical agent over a period of at least about 5, about 10, about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, about 100, or about 120 days. E51. The formulation of any one of embodiments E1-E50, wherein complete release of the pharmaceutical agent from the hydrogel formed by the formulation is achieved after at least about 10, about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, about 100, about 110, about 120, about 130 days. E52. The formulation of any one of embodiments E1-E51, where the hydrogel formed by the formulation comprises a nearly first-order release of the pharmaceutical agent. E53. The formulation of any one of embodiments E1-E52, wherein the formulation has a viscosity of less than about 4000 cP, about 2000 cP, about 1000 cP, about 800 cP, about 600 cP, about 500 cP, about 400 cP, about 200 cP, about 100 cP, about 80 cP, about 60 cP, about 50 cP, about 40 cP, about 20 cP, about 10 cP, about 8 cP, about 6 cP, about 5 cP, about 4 cP, about 3 cP, about 2 cP about 1 cP prior to formation of the hydrogel. E54. The formulation of any one of embodiments E1-E53, wherein the pharmaceutical agent comprises an anti- inflammatory agent, a steroid, an NSAID, an intraocular pressure lowering drug, an antibiotic, a pain reliever, an inhibitor of vascular endothelial growth factor (VEGF), an inhibitor of abnormal vascular growth or vascular leakage, an inhibitor or modifier of the complement pathway, a neuroprotectant, an inhibitor of abnormal cell proliferation, a chemotherapeutic, an anti-viral drug, a gene therapy viral vector, or a combination thereof. E55. The formulation of any one of embodiments E1-E54, wherein the pharmaceutical agent comprises a small molecule, a protein, a DNA or RNA fragment, a glycosaminoglycan, a carbohydrate, a nucleic acid, an inorganic and organic biologically active compound, an active portion of any of the proceeding, or a combination thereof. E56. The formulation of any one of embodiments E1-E55, wherein the pharmaceutical agent comprises an antibody, a bi-specific antibody, a single-chain variable fragment (scFv), an active portion of any of the proceeding, or a combination thereof. E57. The formulation of any one of embodiments E1-E56, wherein the pharmaceutical agent comprises an anti-cancer agent. E58. The formulation of any one of embodiments E1-E57, wherein the pharmaceutical agent comprises bevacizumab. E59. The formulation of any one of embodiments E1-E58, wherein the pharmaceutically acceptable carrier comprises water. E60. The formulation of any one of embodiments E1-E59, wherein the pharmaceutically acceptable carrier comprises PBS. E61. The formulation of embodiment 60, wherein the PBS comprises one or more of sodium chloride, potassium chloride, sodium phosphate and potassium phosphate. E62. The formulation of any one of embodiments E1-E61, wherein the formulation is an ocular formulation. [0013] E63. A formulation for use in forming an extended-release hydrogel, the formulation comprising: a. a nucleo-functional polymer that is a biocompatible polymer containing a plurality of thio-functional groups -R1-SH wherein R1 is an ester-containing linker; b. a pharmaceutical agent; and c. a pharmaceutically acceptable carrier. E64. The formulation of embodiment 63, wherein the nucleo-functional polymer is a biocompatible polymer comprising poly(vinyl alcohol). E65. The formulation of embodiment 63 or 64, wherein the nucleo- functional polymer comprises a biocompatible poly(vinyl alcohol) polymer substituted by a plurality of thio-functional groups -R1-SH. E66. The formulation of any one of embodiments E63-E65, wherein the nucleo-functional polymer comprises a biocompatible, partially hydrolyzed poly(vinyl alcohol). E67. The formulation of embodiment 66, wherein the partially hydrolyzed poly(vinyl alcohol) polymer has a degree of hydrolysis in the range of about 75% to about 99.9%. E68. The formulation of any one of embodiments E63-E67, wherein the thio- functional group -R1-SH is -OC(O)-(C1-C6 alkylene)-SH. E69. The formulation of any one of embodiments E63-E68, wherein the thio-functional group -R1-SH is -OC(O)-(CH2CH2)-SH. E70. The formulation of embodiment 63, wherein the nucleo-functional polymer is a biocompatible poly(vinyl alcohol) polymer comprising:
Figure imgf000010_0001
wherein a is an integer from 1 to about 20 and b is an integer from 1 to about 20. E71. The formulation of embodiment 63, wherein the nucleo-functional polymer is a biocompatible poly(vinyl alcohol) polymer comprising: wherein a is an integer from 1 to
Figure imgf000010_0002
about 20, b is an integer from 1 to about 20, and c is an integer from about 20 to about 500. E72. The formulation of any one of embodiments E63-E71, wherein the nucleo-functional polymer has a weight-average molecular weight in the range of from about 4,000 g/mol to about 100,000 g/mol. E73. The formulation of any one of embodiments E63-E72, wherein the nucleo-functional polymer has a weight-average molecular weight in the range of from about 15,000 g/mol to about 25,000 g/mol. E74. The formulation of any one of embodiments E63-E71, wherein the nucleo-functional polymer has a weight-average molecular weight of less than about 75,000 g/mol. E75. The formulation of any one of embodiments E63-E74, wherein the formulation comprises water, and the formulation has a pH in the range of about 7.1 to about 7.7. E76. The formulation of any one of embodiments E63-E75, wherein the formulation comprises water, and the formulation has a pH in the range of about 7.3 to about 7.5. E77. The formulation of any one of embodiments E63-E76, wherein the formulation comprises water, and the formulation has a pH of about 7.4. E78. The formulation of any one of embodiments E63-E77, further comprising an alkali metal salt. E79. The formulation of any one of embodiments E63-E78, further comprising an alkali metal halide salt, an alkaline earth metal halide salt, or a combination thereof. E80. The formulation of any one of embodiments E63-E79, further comprising sodium chloride, potassium chloride, calcium chloride, magnesium chloride, or a combination thereof. E81. The formulation of any one of embodiments E63-E80, wherein the formulation has an osmolality in the range of about 200 mOsm / kg to about 400 mOsm / kg. E82. The formulation of any one of embodiments E63-E81, wherein the formulation has an osmolality in the range of about 250 mOsm / kg to about 350 mOsm / kg. E83. The formulation of any one of embodiments E63-E82, wherein the formulation has an osmolality in the range of about 280 mOsm / kg to about 320 mOsm / kg. E84. The formulation of any one of embodiments E63-E83, wherein the formulation has an osmolality of about 300 mOsm / kg. E85. The formulation of any one of embodiments E63-E84, wherein the formulation has an endotoxin level of less than about 20 endotoxin units/ml, less than about 15 endotoxin units/ml, less than about 10 endotoxin units/ml, less than about 5 endotoxin units/ml, less than about 2.5 endotoxin units/ml, less than about 1.0 endotoxin units/ml, less than about 0.8 endotoxin units/ml, less than about 0.5 endotoxin units/ml, less than about 0.2 endotoxin units/ml, or less than about 0.1 endotoxin units/ml. E86. The formulation of any one of embodiments E63-E85, wherein the formulation has less than about 50 particles per mL with a size of ^ 10 μm. E87. The formulation of any one of embodiments E63-E86, wherein the formulation has less than about 5 particles per mL with a size of ^ 25 μm. E88. The formulation of any one of embodiments E63-E87, wherein the formulation has a viscosity of less than about 4000 cP, about 2000 cP, about 1000 cP, about 800 cP, about 600 cP, about 500 cP, about 400 cP, about 200 cP, about 100 cP, about 80 cP, about 60 cP, about 50 cP, about 40 cP, about 20 cP, about 10 cP, about 8 cP, about 6 cP, about 5 cP, about 4 cP, about 3 cP, about 2 cP about 1 cP prior to formation of the hydrogel. E89. The formulation of any one of embodiments E63-E88, wherein the pharmaceutical agent comprises an anti- inflammatory agent, a steroid, an NSAID, an intraocular pressure lowering drug, an antibiotic, a pain reliever, an inhibitor of vascular endothelial growth factor (VEGF), an inhibitor of abnormal vascular growth or vascular leakage, an inhibitor of abnormal cell proliferation, a chemotherapeutic, an anti-viral drug, a gene therapy viral vector, or a combination thereof. E90. The formulation of any one of embodiments E63-E89, wherein the pharmaceutical agent comprises a small molecule, a protein, a DNA or RNA fragment, a glycosaminoglycan, a carbohydrate, a nucleic acid, an inorganic and organic biologically active compound, an active portion of any of the proceeding, or a combination thereof. E91. The formulation of any one of embodiments E63-E90, wherein the pharmaceutical agent comprises an antibody, a bi-specific antibody, a single-chain variable fragment (scFv), an active portion of any of the proceeding, or a combination thereof. E92. The formulation of any one of embodiments E63-E91, wherein the pharmaceutical agent comprises an anti-cancer agent. E93. The formulation of any one of embodiments E63-E92, wherein the pharmaceutical agent comprises bevacizumab. E94. The formulation of any one of embodiments E63-E93, wherein the pharmaceutically acceptable carrier comprises water. E95. The formulation of any one of embodiments E63-E94, wherein the pharmaceutically acceptable carrier comprises PBS. E96. The formulation of embodiment 95, wherein the PBS comprises one or more of sodium chloride, potassium chloride, sodium phosphate and potassium phosphate. E97. The formulation of any one of embodiments E63-E96, wherein the formulation is an ocular formulation. [0014] E98. A formulation for forming an extended-release hydrogel, the formulation comprising: a. an electro-functional polymer that is a biocompatible polymer containing at least one thiol-reactive group; b. a pharmaceutical agent; and c. a pharmaceutically acceptable carrier. E99. The formulation of embodiment 98, wherein the electro-functional polymer is a biocompatible polymer comprising poly(ethylene glycol). E100. The formulation of embodiment 98 or 99, wherein the electro-functional polymer is a biocompatible polymer comprising poly(ethylene glycol)polymer substituted by at least one thiol-reactive group. E101. The formulation of any one of embodiments E98-E100, wherein the thiol-reactive group is an alpha- beta unsaturated ester, maleimidyl, sulfone, or combinations thereof. E102. The formulation of embodiment 101, wherein the alpha-beta unsaturated ester, maleimidyl, or sulfone is optionally substituted by one or more occurrences of alkyl, aryl, or aralkyl. E103. The formulation of any one of embodiments E98-E102, wherein the thiol-reactive group is acrylate, maleimide, or vinylsulfone. E104. The formulation of any one of embodiments E98-E103, wherein the electro- functional polymer has a weight-average molecular weight in the range of from about 500 g/mol to about 100,000 g/mol. E105. The formulation of any one of embodiments E98-E104, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 1,000 g/mol to about 50,000 g/mol. E106. The formulation of any one of embodiments E98- E105, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 2,000 g/mol to about 20,000 g/mol. E107. The formulation of any one of embodiments E98-E106, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 2,700 g/mol to about 3,000 g/mol. E108. The formulation of any one of embodiments E98-E107, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 9,000 g/mol to about 11,000 g/mol. E109. The formulation of any one of embodiments E98-E108, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 18,000 g/mol to about 22,000 g/mol. E110. The formulation of any one of embodiments E98-E109, wherein the electro- functional polymer comprises a multi-arm polymer. E111. The formulation of embodiment 110, wherein the multi-arm polymer comprises as 4-arm polyethylene glycol maleimide, 4-arm polyethylene glycol acrylate, 4-arm polyethylene glycol vinyl sulfone, 8-arm polyethylene glycol maleimide, 8-arm polyethylene glycol acrylate, 8-arm polyethylene glycol vinyl sulfone, or combinations thereof. E112. The formulation of any one of embodiments E98-E111, wherein the formulation comprises water, and the formulation has a pH in the range of about 7.1 to about 7.7. E113. The formulation of any one of embodiments E98-E112, wherein the formulation comprises water, and the formulation has a pH in the range of about 7.3 to about 7.5. E114. The formulation of any one of embodiments E98-E113, wherein the formulation comprises water, and the formulation has a pH of about 7.4. E115. The formulation of any one of embodiments E98-E114, further comprising an alkali metal salt. E116. The formulation of any one of embodiments E98-E115, further comprising an alkali metal halide salt, an alkaline earth metal halide salt, or a combination thereof. E117. The formulation of any one of embodiments E98- E116, further comprising sodium chloride, potassium chloride, calcium chloride, magnesium chloride, or a combination thereof. E118. The formulation of any one of embodiments E98- E117, wherein the formulation has an osmolality in the range of about 200 mOsm / kg to about 400 mOsm / kg. E119. The formulation of any one of embodiments E98-E118, wherein the formulation has an osmolality in the range of about 250 mOsm / kg to about 350 mOsm / kg. E120. The formulation of any one of embodiments E98-E119, wherein the formulation has an osmolality in the range of about 280 mOsm / kg to about 320 mOsm / kg. E121. The formulation of any one of embodiments E98-E120, wherein the formulation has an osmolality of about 300 mOsm / kg. E122. The formulation of any one of embodiments E98-E121, wherein the formulation has an endotoxin level of less than about 20 endotoxin units/ml, less than about 15 endotoxin units/ml, less than about 10 endotoxin units/ml, less than about 5 endotoxin units/ml, less than about 2.5 endotoxin units/ml, less than about 1.0 endotoxin units/ml, less than about 0.8 endotoxin units/ml, less than about 0.5 endotoxin units/ml, less than about 0.2 endotoxin units/ml, or less than about 0.1 endotoxin units/ml. E123. The formulation of any one of embodiments E98-E122, wherein the formulation has less than about 50 particles per mL with a size of ^ 10 μm. E124. The formulation of any one of embodiments E98-E123, wherein the formulation has less than about 5 particles per mL with a size of ^ 25 μm. E125. The formulation of any one of embodiments E98-E124, wherein the formulation has a viscosity of less than about 4000 cP, about 2000 cP, about 1000 cP, about 800 cP, about 600 cP, about 500 cP, about 400 cP, about 200 cP, about 100 cP, about 80 cP, about 60 cP, about 50 cP, about 40 cP, about 20 cP, about 10 cP, about 8 cP, about 6 cP, about 5 cP, about 4 cP, about 3 cP, about 2 cP about 1 cP prior to formation of the hydrogel. E126. The formulation of any one of embodiments E98-E125, wherein the pharmaceutical agent comprises an anti-inflammatory agent, a steroid, an NSAID, an intraocular pressure lowering drug, an antibiotic, a pain reliever, an inhibitor of vascular endothelial growth factor (VEGF), an inhibitor of abnormal vascular growth or vascular leakage, an inhibitor of abnormal cell proliferation, a chemotherapeutic, an anti-viral drug, a gene therapy viral vector, or a combination thereof. E127. The formulation of any one of embodiments E98-E126, wherein the pharmaceutical agent comprises a small molecule, a protein, a DNA or RNA fragment, a glycosaminoglycan, a carbohydrate, a nucleic acid, an inorganic and organic biologically active compound, an active portion of any of the proceeding, or a combination thereof. E128. The formulation of any one of embodiments E98- E127, wherein the pharmaceutical agent comprises an antibody, a bi-specific antibody, a single- chain variable fragment (scFv), an active portion of any of the proceeding, or a combination thereof. E129. The formulation of any one of embodiments E98-E128, wherein the pharmaceutical agent comprises an anti-cancer agent. E130. The formulation of any one of embodiments E98-E129, wherein the pharmaceutical agent comprises bevacizumab. E131. The formulation of any one of embodiments E98-E130, wherein the pharmaceutically acceptable carrier comprises water. E132. The formulation of any one of embodiments E98-E131, wherein the pharmaceutically acceptable carrier comprises PBS. E133. The formulation of embodiment 132, wherein the PBS comprises one or more of sodium chloride, potassium chloride, sodium phosphate and potassium phosphate. E134. The formulation of any one of embodiments E98- E133, wherein the formulation is an ocular formulation. [0015] E135. An extended-release hydrogel comprising: a. a nucleo-functional polymer that is a biocompatible polymer containing a plurality of thio-functional groups -R1-SH wherein R1 is an ester-containing linker; b. an electro-functional polymer that is a biocompatible polymer containing at least one thiol-reactive group; and c. a pharmaceutical agent. E136. The extended- release hydrogel of embodiment 135, further comprising a pharmaceutically acceptable carrier. E137. The extended-release hydrogel of embodiment 135 or 136, wherein the nucleo-functional polymer is a biocompatible polymer comprising poly(vinyl alcohol). E138. The extended-release hydrogel of any of embodiments E135-E137, wherein the nucleo-functional polymer comprises a biocompatible poly(vinyl alcohol) polymer substituted by a plurality of thio-functional groups - R1-SH. E139. The extended-release hydrogel of any of embodiments E135-E138, wherein the nucleo-functional polymer comprises a biocompatible, partially hydrolyzed poly(vinyl alcohol). E140. The extended-release hydrogel of embodiment 139, wherein the partially hydrolyzed poly(vinyl alcohol) polymer has a degree of hydrolysis in the range of about 75% to about 99.9%. E141. The extended-release hydrogel of any one of embodiments E135-E140, wherein the thio-functional group -R1-SH is -OC(O)-(C1-C6 alkylene)-SH. E142. The extended-release hydrogel of any one of embodiments E135-E141, wherein the thio-functional group -R1-SH is - OC(O)-(CH2CH2)-SH. E143. The extended-release hydrogel of embodiment 135, wherein the nucleo-functional polymer is a biocompatible poly(vinyl alcohol) polymer comprising:
Figure imgf000016_0001
wherein a is an integer from 1 to about 20 and b is an integer from 1 to about 20. E144. The extended-release hydrogel of embodiment 135, wherein the nucleo-functional polymer is a biocompatible poly(vinyl alcohol) polymer comprising:
Figure imgf000016_0002
wherein a is an integer from 1 to about 20, b is an integer from 1 to about 20, and c is an integer from about 20 to about 500. E145. The extended- release hydrogel of any one of embodiments E135-E144, wherein the nucleo-functional polymer has a weight-average molecular weight in the range of from about 4,000 g/mol to about 100,000 g/mol. E146. The extended-release hydrogel of any one of embodiments E135-E145, wherein the nucleo-functional polymer has a weight-average molecular weight in the range of from about 15,000 g/mol to about 25,000 g/mol. E147. The extended-release hydrogel of any one of embodiments E135-E145, wherein the nucleo-functional polymer has a weight-average molecular weight of less than about 75,000 g/mol. E148. The extended-release hydrogel of any one of embodiments E135-E147, wherein the electro-functional polymer is a biocompatible polymer comprising poly(ethylene glycol). E149. The extended-release hydrogel of any one of embodiments E135-E148, wherein the electro-functional polymer is a biocompatible polymer comprising poly(ethylene glycol)polymer substituted by at least one thiol-reactive group. E150. The extended-release hydrogel of any one of embodiments E135-E149, wherein the thiol- reactive group is an alpha-beta unsaturated ester, maleimidyl, sulfone, or combinations thereof. E151. The extended-release hydrogel of embodiment 150, wherein the alpha-beta unsaturated ester, maleimidyl, or sulfone is optionally substituted by one or more occurrences of alkyl, aryl, or aralkyl. E152. The extended-release hydrogel of any one of embodiments E135-E151, wherein the thiol-reactive group is acrylate, maleimide, or vinylsulfone. E153. The extended- release hydrogel of any one of embodiments E135-E152, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 500 g/mol to about 100,000 g/mol. E154. The extended-release hydrogel of any one of embodiments E135-E153, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 1,000 g/mol to about 50,000 g/mol. E155. The extended-release hydrogel of any one of embodiments E135-E154, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 2,000 g/mol to about 20,000 g/mol. E156. The extended-release hydrogel of any one of embodiments E135-E155, wherein the electro- functional polymer has a weight-average molecular weight in the range of from about 2,700 g/mol to about 3,000 g/mol. E157. The extended-release hydrogel of any one of embodiments E135-E156, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 9,000 g/mol to about 11,000 g/mol. E158. The extended-release hydrogel of any one of embodiments E135-E157, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 18,000 g/mol to about 22,000 g/mol. E159. The extended-release hydrogel of any one of embodiments E135-E158, wherein the electro-functional polymer comprises a multi-arm polymer. E160. The extended-release hydrogel of embodiment 159, wherein the multi-arm polymer comprises as 4-arm polyethylene glycol maleimide, 4-arm polyethylene glycol acrylate, 4-arm polyethylene glycol vinyl sulfone, 8-arm polyethylene glycol maleimide, 8-arm polyethylene glycol acrylate, 8-arm polyethylene glycol vinyl sulfone, or combinations thereof. E161. The extended-release hydrogel of any one of embodiments E135-E160, wherein the mole ratio of (i) thio-functional groups -R1-SH to (ii) thiol-reactive group is in the range of about 10:1 to about 1:10. E162. The extended-release hydrogel of any one of embodiments E135-E161, wherein the mole ratio of (i) thio-functional groups -R1-SH to (ii) thiol-reactive groups is in the range of about 2:1 to about 1:2. E163. The extended-release hydrogel of any one of embodiments E135-E161, wherein the mole ratio of (i) thio-functional groups -R1-SH to (ii) thiol-reactive groups is in the range of about 0.8:1 to about 1.2:1. E164. The extended-release hydrogel of any one of embodiments E135-E163, wherein the formulation comprises water, and the formulation has a pH in the range of about 7.1 to about 7.7. E165. The extended-release hydrogel of any one of embodiments E135-E163, wherein the formulation comprises water, and the formulation has a pH in the range of about 7.3 to about 7.5. E166. The extended-release hydrogel of any one of embodiments E135-E163, wherein the formulation comprises water, and the formulation has a pH of about 7.4. E167. The extended- release hydrogel of any one of embodiments E135-E166, further comprising an alkali metal salt. E168. The extended-release hydrogel of any one of embodiments E135-E167, further comprising an alkali metal halide salt, an alkaline earth metal halide salt, or a combination thereof. E169. The extended-release hydrogel of any one of embodiments E135-E168, further comprising sodium chloride, potassium chloride, calcium chloride, magnesium chloride, or a combination thereof. E170. The extended-release hydrogel of any one of embodiments E135-E161, wherein the extended-release hydrogel has a transparency of at least about 80% for light in the visible spectrum when measured through a hydrogel having a thickness of 2 cm. E171. The extended- release hydrogel of any one of embodiments E135-E170, wherein the extended-release hydrogel has a transparency of at least about 85% for light in the visible spectrum when measured through a hydrogel having a thickness of 2 cm. E172. The extended-release hydrogel of any one of embodiments E135-E171, wherein the extended-release hydrogel has a transparency or at least about 90% for light in the visible spectrum when measured through a hydrogel having a thickness of 2 cm. E173. The extended-release hydrogel of any one of embodiments E135-E172, wherein the extended-release hydrogel has a crosslink time of less than about 10 minutes, less than about 7 minutes, less than about 5 minutes, less than about 3 minutes, less than about 1 minute, less than about 20 seconds, less than about 10 seconds, less than about 5 seconds, or less than about 1 second after mixing the nucleo-functional polymer and the electro-functional polymer when measured at 37°C. E174. The extended-release hydrogel of any one of embodiments E135-E173, wherein the extended-release hydrogel has a degradation time that is greater than or equal to about 3, about 5, about 8, about 10, about 13, about 14, about 15, about 19, or about 32 days at 60°C. E175. The extended-release hydrogel of any one of embodiments E135-E174, wherein the extended-release hydrogel has a degradation time that is greater than or equal to about 20, about 40, about 60, about 69, about 80, about 94, about 100, or about 158 days at 37°C. E176. The extended-release hydrogel of any one of embodiments E135-E175, wherein the extended-release hydrogel acts as a depot for the pharmaceutical agent. E177. The extended- release hydrogel of any one of embodiments E135-E176, wherein the extended-release hydrogel provides for extended-release of the pharmaceutical agent. E178. The extended-release hydrogel of any one of embodiments E135-E177, wherein the extended-release hydrogel releases the pharmaceutical agent over a period of at least about 5, about 10, about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, about 100, or about 120 days. E179. The extended-release hydrogel of any one of embodiments E135-E178, wherein complete release of the pharmaceutical agent from the extended-release hydrogel is achieved after at least about 10, about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, about 100, about 110, about 120, about 130 days. E180. The extended-release hydrogel of any one of embodiments E135-E179, where the extended-release hydrogel comprises a nearly first-order release of the pharmaceutical agent. E181. The extended-release hydrogel of any one of embodiments E135-E180, wherein the pharmaceutical agent comprises an anti-inflammatory agent, a steroid, an NSAID, an intraocular pressure lowering drug, an antibiotic, a pain reliever, an inhibitor of vascular endothelial growth factor (VEGF), an inhibitor of abnormal vascular growth or vascular leakage, an inhibitor of abnormal cell proliferation, a chemotherapeutic, an anti-viral drug, a gene therapy viral vector, or a combination thereof. E182. The extended-release hydrogel of any one of embodiments E135-E181, wherein the pharmaceutical agent comprises a small molecule, a protein, a DNA or RNA fragment, a glycosaminoglycan, a carbohydrate, a nucleic acid, an inorganic and organic biologically active compound, an active portion of any of the proceeding, or a combination thereof. E183. The extended-release hydrogel of any one of embodiments E135-E182, wherein the pharmaceutical agent comprises an antibody, a bi-specific antibody, a single-chain variable fragment (scFv), an active portion of any of the proceeding, or a combination thereof. E184. The extended-release hydrogel of any one of embodiments E135- E183, wherein the pharmaceutical agent comprises an anti-cancer agent. E185. The extended- release hydrogel of any one of embodiments E135-E184, wherein the pharmaceutical agent comprises bevacizumab. E186. The extended-release hydrogel of any one of embodiments E136- E185, wherein the pharmaceutically acceptable carrier comprises water. E187. The extended- release hydrogel of any one of embodiments E136-E186, wherein the pharmaceutically acceptable carrier comprises PBS. E188. The extended-release hydrogel of embodiment 187, wherein the PBS comprises one or more of sodium chloride, potassium chloride, sodium phosphate and potassium phosphate. E189. The extended-release hydrogel of any one of embodiments E135-188, wherein the extended-release hydrogel is for use in the eye of a subject. [0016] E190. A method for administering a pharmaceutical agent to a subject in need thereof, the method comprising: a. administering to the subject an effective amount of a nucleo- functional polymer, an electro-functional polymer, a pharmaceutical agent, and a pharmaceutically acceptable carrier; and b. allowing the nucleo-functional polymer and the electro-functional polymer to react to form an extended-release hydrogel in the subject; wherein the nucleo-functional polymer is a biocompatible polymer containing a plurality of thio- functional groups -R1-SH wherein R1 is an ester-containing linker, and the electro- functional polymer is a biocompatible polymer containing at least one thiol-reactive group. E191. The method of embodiment 190, wherein the nucleo-functional polymer, the electro-functional polymer, the pharmaceutical agent, and the pharmaceutically acceptable carrier are administered to the subject together in a single formulation. E192. The method of embodiment 190, wherein the nucleo-functional polymer and the electro-functional polymer are administered to the subject in separate formulations and following administration to the subject, the nucleo-functional polymer and the electro-functional polymer mix and react to form the extended-release hydrogel in the subject. E193. The method of embodiment 192, wherein the formulation comprising the nucleo-functional polymer comprises the pharmaceutical agent. E194. The method of embodiment 192 or 193, wherein the formulation comprising the electro-functional polymer comprises the pharmaceutical agent. E195. The method of any one of embodiments E192-E194, wherein the formulation comprising the nucleo-functional polymer comprises the pharmaceutically acceptable carrier. E196. The method of any one of embodiments E192-E195, wherein the formulation comprising the electro-functional polymer comprises the pharmaceutically acceptable carrier. E197. The method of any one of embodiments E190-E196, wherein the nucleo-functional polymer is a biocompatible polymer comprising poly(vinyl alcohol). E198. The method of any one of embodiments E190-E197, wherein the nucleo- functional polymer comprises a biocompatible poly(vinyl alcohol) polymer substituted by a plurality of thio-functional groups -R1-SH. E199. The method of any of embodiments E190- E198, wherein the nucleo-functional polymer comprises a biocompatible, partially hydrolyzed poly(vinyl alcohol). E200. The method of embodiment 199, wherein the partially hydrolyzed poly(vinyl alcohol) polymer has a degree of hydrolysis in the range of about 75% to about 99.9%. E201. The method of any one of embodiments E190-E200, wherein the thio-functional group -R1-SH is -OC(O)-(C1-C6 alkylene)-SH. E202. The method of any one of embodiments E190-E201, wherein the thio-functional group -R1-SH is -OC(O)-(CH2CH2)-SH. E203. The method of any one of embodiments E190-E196, wherein the nucleo-functional polymer is a
Figure imgf000021_0001
biocompatible poly(vinyl alcohol) polymer comprising: wherein a is an integer from 1 to about 20 and b is an integer from 1 to about 20. E204. The method of any one of embodiments E190-E196, wherein the nucleo-functional polymer is a biocompatible poly(vinyl alcohol) polymer comprising:
Figure imgf000021_0002
wherein a is an integer from 1 to about 20, b is an integer from 1 to about 20, and c is an integer from about 20 to about 500. E205. The method of any one of embodiments E190-E204, wherein the nucleo- functional polymer has a weight-average molecular weight in the range of from about 4,000 g/mol to about 100,000 g/mol. E206. The method of any one of embodiments E190-E205, wherein the nucleo-functional polymer has a weight-average molecular weight in the range of from about 15,000 g/mol to about 25,000 g/mol. E207. The method of any one of embodiments E190-E206, wherein the nucleo-functional polymer has a weight-average molecular weight of less than about 75,000 g/mol. E208. The method of any one of embodiments E190-E207, wherein the electro-functional polymer is a biocompatible polymer comprising poly(ethylene glycol). E209. The method of any one of embodiments E190-E208, wherein the electro- functional polymer is a biocompatible polymer comprising poly(ethylene glycol)polymer substituted by at least one thiol-reactive group. E210. The method of any one of embodiments E190-E209, wherein the thiol-reactive group is an alpha-beta unsaturated ester, maleimidyl, sulfone, or combinations thereof. E211. The method of embodiment 210, wherein the alpha-beta unsaturated ester, maleimidyl, or sulfone is optionally substituted by one or more occurrences of alkyl, aryl, or aralkyl. E212. The method of any one of embodiments E190-E211, wherein the thiol-reactive group is acrylate, maleimide, or vinylsulfone. E213. The method of any one of embodiments E190-E212, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 500 g/mol to about 100,000 g/mol. E214. The method of any one of embodiments E190-E213, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 1,000 g/mol to about 50,000 g/mol. E215. The method of any one of embodiments E190-E214, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 2,000 g/mol to about 20,000 g/mol. E216. The method of any one of embodiments E190-E215, wherein the electro- functional polymer has a weight-average molecular weight in the range of from about 2,700 g/mol to about 3,000 g/mol. E217. The method of any one of embodiments E190-E216, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 9,000 g/mol to about 11,000 g/mol. E218. The method of any one of embodiments E190-E217, wherein the electro-functional polymer has a weight-average molecular weight in the range of from about 18,000 g/mol to about 22,000 g/mol. E219. The method of any one of embodiments E190-E218, wherein the electro-functional polymer comprises a multi-arm polymer. E220. The method of embodiment 219, wherein the multi-arm polymer comprises as 4-arm polyethylene glycol maleimide, 4-arm polyethylene glycol acrylate, 4-arm polyethylene glycol vinyl sulfone, 8-arm polyethylene glycol maleimide, 8-arm polyethylene glycol acrylate, 8-arm polyethylene glycol vinyl sulfone, or combinations thereof. E221. The method of any one of embodiments E190-E220, wherein the mole ratio of (i) thio-functional groups -R1-SH to (ii) thiol-reactive group is in the range of about 10:1 to about 1:10. E222. The method of any one of embodiments E190-E221, wherein the mole ratio of (i) thio-functional groups -R1-SH to (ii) thiol-reactive groups is in the range of about 2:1 to about 1:2. E223. The method of any one of embodiments E190-E222, wherein the mole ratio of (i) thio-functional groups -R1-SH to (ii) thiol-reactive groups is in the range of about 0.8:1 to about 1.2:1. E224. The method of any one of embodiments E191-E223, wherein the formulation comprises water, and the formulation has a pH in the range of about 7.1 to about 7.7. E225. The method of any one of embodiments E191- E224, wherein the formulation comprises water, and the formulation has a pH in the range of about 7.3 to about 7.5. E226. The method of any one of embodiments E191-E225, wherein the formulation comprises water, and the formulation has a pH of about 7.4. E227. The method of any one of embodiments E191-E226, where the formulation further comprises an alkali metal salt. E228. The method of any one of embodiments E191-E227, wherein the formulation further comprises an alkali metal halide salt, an alkaline earth metal halide salt, or a combination thereof. E229. The method of any one of embodiments E191-E228, wherein the formulation further comprises sodium chloride, potassium chloride, calcium chloride, magnesium chloride, or a combination thereof. E230. The method of any one of embodiments E191-E229, wherein the formulation has an osmolality in the range of about 200 mOsm / kg to about 400 mOsm / kg. E231. The method of any one of embodiments E191-E230, wherein the formulation has an osmolality in the range of about 250 mOsm / kg to about 350 mOsm / kg. E232. The method of any one of embodiments E191-E231, wherein the formulation has an osmolality in the range of about 280 mOsm / kg to about 320 mOsm / kg. E233. The method of any one of embodiments E191-E232, wherein the formulation has an osmolality of about 300 mOsm / kg. E234. The method of any one of embodiments E191-E233, wherein the formulation has an endotoxin level of less than about 20 endotoxin units/ml, less than about 15 endotoxin units/ml, less than about 10 endotoxin units/ml, less than about 5 endotoxin units/ml, less than about 2.5 endotoxin units/ml, less than about 1.0 endotoxin units/ml, less than about 0.8 endotoxin units/ml, less than about 0.5 endotoxin units/ml, less than about 0.2 endotoxin units/ml, or less than about 0.1 endotoxin units/ml. E235. The method of any one of embodiments E191-E234, wherein the formulation has less than about 50 particles per mL with a size of ^ 10 μm. E236. The method of any one of embodiments E191-E235, wherein the formulation has less than about 5 particles per mL with a size of ^ 25 μm. E237. The method of any one of embodiments E190-E236, wherein the extended-release hydrogel has a transparency of at least about 80% for light in the visible spectrum when measured through a hydrogel having a thickness of 2 cm. E238. The method of any one of embodiments E190-E237, wherein the extended-release hydrogel has a transparency of at least about 85% for light in the visible spectrum when measured through a hydrogel having a thickness of 2 cm. E239. The method of any one of embodiments E190-E238, wherein the extended-release hydrogel has a transparency or at least about 90% for light in the visible spectrum when measured through a hydrogel having a thickness of 2 cm. E240. The method of any one of embodiments E191-E239, wherein the extended-release hydrogel has a crosslink time of less than about 10 minutes, less than about 7 minutes, less than about 5 minutes, less than about 3 minutes, less than about 1 minute, less than about 20 seconds, less than about 10 seconds, less than about 5 seconds, or less than about 1 second when measured at 37°C. E241. The method of any one of embodiments E190-E240, wherein the extended-release hydrogel has a degradation time that is greater than or equal to about 3, about 5, about 8, about 10, about 13, about 14, about 15, about 19, or about 32 days at 60°C. E242. The method of any one of embodiments E190-E241, wherein the extended-release hydrogel has a degradation time that is greater than or equal to about 20, about 40, about 60, about 69, about 80, about 94, about 100, or about 158 days at 37°C. E243. The method of any one of embodiments E190-E242, wherein the extended-release hydrogel acts as a depot for the pharmaceutical agent. E244. The method of any one of embodiments E190-E243, wherein the extended-release hydrogel provides for extended-release of the pharmaceutical agent. E245. The method of any one of embodiments E190-E244, wherein the extended-release hydrogel releases the pharmaceutical agent over a period of at least about 5, about 10, about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, about 100, or about 120 days. E246. The method of any one of embodiments E190-E245, wherein complete release of the pharmaceutical agent from the extended-release hydrogel is achieved after at least about 10, about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, about 100, about 110, about 120, about 130 days. E247. The method of any one of embodiments E190-E246, where the extended-release hydrogel comprises a nearly first-order release of the pharmaceutical agent. E248. The method of any one of embodiments E190-E247, wherein the formulation has a viscosity of less than about 4000 cP, about 2000 cP, about 1000 cP, about 800 cP, about 600 cP, about 500 cP, about 400 cP, about 200 cP, about 100 cP, about 80 cP, about 60 cP, about 50 cP, about 40 cP, about 20 cP, about 10 cP, about 8 cP, about 6 cP, about 5 cP, about 4 cP, about 3 cP, about 2 cP about 1 cP prior to formation of the hydrogel. E249. The method of any one of embodiments E190-E248, wherein the pharmaceutical agent comprises an anti-inflammatory agent, a steroid, an NSAID, an intraocular pressure lowering drug, an antibiotic, a pain reliever, an inhibitor of vascular endothelial growth factor (VEGF), an inhibitor of abnormal vascular growth or vascular leakage, an inhibitor of abnormal cell proliferation, a chemotherapeutic, an anti-viral drug, a gene therapy viral vector, or a combination thereof. E250. The method of any one of embodiments E190- E249, wherein the pharmaceutical agent comprises a small molecule, a protein, a DNA or RNA fragment, a glycosaminoglycan, a carbohydrate, a nucleic acid, an inorganic and organic biologically active compound, an active portion of any of the proceeding, or a combination thereof. E251. The method of any one of embodiments E190-E250, wherein the pharmaceutical agent comprises an antibody, a bi-specific antibody, a single-chain variable fragment (scFv), an active portion of any of the proceeding, or a combination thereof. E252. The method of any one of embodiments E190-E251, wherein the pharmaceutical agent comprises an anti-cancer agent. E253. The method of any one of embodiments E190-E252, wherein the pharmaceutical agent comprises bevacizumab. E254. The method of any one of embodiments E190-E253, wherein the pharmaceutically acceptable carrier comprises water. E255. The method of any one of embodiments E190-E254, wherein the pharmaceutically acceptable carrier comprises PBS. E256. The method of embodiment 255, wherein the PBS comprises one or more of sodium chloride, potassium chloride, sodium phosphate and potassium phosphate. E257. The method of any one of embodiments E191-E256, wherein the formulation is an ocular formulation. E258. The method of any one of embodiments E190-E257, wherein the nucleo-functional polymer, the electro-functional polymer, the pharmaceutical agent, and the pharmaceutically acceptable carrier are administered to the eye of a subject. E259. The method of embodiment 258, wherein the nucleo-functional polymer, the electro-functional polymer, the pharmaceutical agent, and the pharmaceutically acceptable carrier are administered to the vitreous cavity. E260. The method of embodiment 259, wherein the vitreous cavity comprises vitreous. E261. The method of any one of embodiments E258-E260, wherein the nucleo-functional polymer, the electro-functional polymer, the pharmaceutical agent, and the pharmaceutically acceptable carrier are administered as an intravitreal injection. E261. The method of any one of embodiments E258-E261, wherein the subject has not undergone a vitrectomy. E262. The method of any one of embodiments E258- E261, wherein the subject has undergone a partial or complete vitrectomy. E263. The method of any one of embodiments E190-E263, wherein the subject suffers from age-related macular degeneration (AMD), proliferative diabetic retinopathy, proliferative vitreoretinopathy, ocular malignancies, inherited retinal diseases, diabetic macular edema, macular edema from retinal vein occlusions, choroidal neovascularization, uveitis, or a combination thereof. Various aspects and embodiments of the invention are described in further detail below, along with further description of multiple advantages provided by the invention. BRIEF DESCRIPTION OF THE DRAWINGS [0017] FIGURE 1 shows the release of FITC-Dextran over time from exemplary extended- release hydrogels described herein. [0018] FIGURE 2 shows the release of FITC-Dextran over time from an exemplary extended-release hydrogel described herein. [0019] FIGURES 3A and 3B show the release of a large protein, Bevacizumab, from exemplary extended-release hydrogels described herein. [0020] FIGURE 4 shows the release of an encapsulated small molecule, tacrolimus, from an exemplary extended-release hydrogel described herein. [0021] FIGURE 5 shows the release of a large protein, Bevacizumab, from an exemplary extended-release hydrogel described herein. DETAILED DESCRIPTION OF THE INVENTION [0022] Various aspects of the invention are set forth below in sections; however, aspects of the invention described in one particular section are not to be limited to any particular section and are applicable to other sections as appropriate and as would be understood by those of ordinary skill in the art. DEFINITIONS [0023] To facilitate an understanding of the present invention, a number of terms and phrases are defined below. [0024] The terms “a” and “an” as used herein mean “one or more” and include the plural unless the context is inappropriate. [0025] The term “about,” when used to modify a numerical value herein, means ± 10% of that numerical value. For example, “about 100” refers to any number between, and including, 90 to 110. [0026] The term “alkyl” as used herein refers to a saturated straight or branched hydrocarbon, such as a straight or branched group of 1-12, 1-10, or 1-6 carbon atoms, referred to herein as C1-C12alkyl, C1-C10alkyl, and C1-C6alkyl, respectively. Exemplary alkyl groups include, but are not limited to, methyl, ethyl, propyl, isopropyl, 2-methyl-1-propyl, 2-methyl-2- propyl, 2-methyl-1-butyl, 3-methyl-1-butyl, 2-methyl-3-butyl, 2,2-dimethyl-1-propyl, 2-methyl- 1-pentyl, 3-methyl-1-pentyl, 4-methyl-1-pentyl, 2-methyl-2-pentyl, 3-methyl-2-pentyl, 4-methyl- 2-pentyl, 2,2-dimethyl-1-butyl, 3,3-dimethyl-1-butyl, 2-ethyl-1-butyl, butyl, isobutyl, t-butyl, pentyl, isopentyl, neopentyl, hexyl, heptyl, octyl, etc. [0027] The term “cycloalkyl” refers to a monovalent saturated cyclic, bicyclic, or bridged cyclic (e.g., adamantyl) hydrocarbon group of 3-12, 3-8, 4-8, or 4-6 carbons, referred to herein, e.g., as "C4-8cycloalkyl," derived from a cycloalkane. Exemplary cycloalkyl groups include, but are not limited to, cyclohexanes, cyclopentanes, cyclobutanes and cyclopropanes. [0028] The term “aryl” is art-recognized and refers to a carbocyclic aromatic group. Representative aryl groups include phenyl, naphthyl, anthracenyl, and the like. Unless specified otherwise, the aromatic ring may be substituted at one or more ring positions with, for example, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, alkoxyl, amino, nitro, sulfhydryl, imino, amido, carboxylic acid, -C(O)alkyl, -CO2alkyl, carbonyl, carboxyl, alkylthio, sulfonyl, sulfonamido, sulfonamide, ketone, aldehyde, ester, heterocyclyl, aryl or heteroaryl moieties, -CF3, -CN, or the like. The term “aryl” also includes polycyclic ring systems having two or more carbocyclic rings in which two or more carbons are common to two adjoining rings (the rings are “fused rings”) wherein at least one of the rings is aromatic, e.g., the other cyclic rings may be cycloalkyls, cycloalkenyls, cycloalkynyls, and/or aryls. In certain embodiments, the aromatic ring is substituted at one or more ring positions with halogen, alkyl, hydroxyl, or alkoxyl. In certain other embodiments, the aromatic ring is not substituted, i.e., it is unsubstituted. [0029] The term “aralkyl” refers to an alkyl group substituted with an aryl group. [0030] The term “heteroaryl” is art-recognized and refers to aromatic groups that include at least one ring heteroatom. In certain instances, a heteroaryl group contains 1, 2, 3, or 4 ring heteroatoms. Representative examples of heteroaryl groups include pyrrolyl, furanyl, thiophenyl, imidazolyl, oxazolyl, thiazolyl, triazolyl, pyrazolyl, pyridinyl, pyrazinyl, pyridazinyl and pyrimidinyl, and the like. Unless specified otherwise, the heteroaryl ring may be substituted at one or more ring positions with, for example, halogen, azide, alkyl, aralkyl, alkenyl, alkynyl, cycloalkyl, hydroxyl, alkoxyl, amino, nitro, sulfhydryl, imino, amido, carboxylic acid, -C(O)alkyl, -CO2alkyl, carbonyl, carboxyl, alkylthio, sulfonyl, sulfonamido, sulfonamide, ketone, aldehyde, ester, heterocyclyl, aryl or heteroaryl moieties, -CF3, -CN, or the like. The term “heteroaryl” also includes polycyclic ring systems having two or more rings in which two or more carbons are common to two adjoining rings (the rings are “fused rings”) wherein at least one of the rings is heteroaromatic, e.g., the other cyclic rings may be cycloalkyls, cycloalkenyls, cycloalkynyls, and/or aryls. In certain embodiments, the heteroaryl ring is substituted at one or more ring positions with halogen, alkyl, hydroxyl, or alkoxyl. In certain other embodiments, the heteroaryl ring is not substituted, i.e., it is unsubstituted. [0031] The term “heteroaralkyl” refers to an alkyl group substituted with a heteroaryl group. [0032] The terms ortho, meta and para are art-recognized and refer to 1,2-, 1,3- and 1,4- disubstituted benzenes, respectively. For example, the names 1,2-dimethylbenzene and ortho- dimethylbenzene are synonymous. [0033] The terms “heterocyclyl” and “heterocyclic group” are art-recognized and refer to saturated or partially unsaturated 3- to 10-membered ring structures, alternatively 3- to 7- membered rings, whose ring structures include one to four heteroatoms, such as nitrogen, oxygen, and sulfur. The number of ring atoms in the heterocyclyl group can be specified using Cx- Cx nomenclature where x is an integer specifying the number of ring atoms. For example, a C3-C7heterocyclyl group refers to a saturated or partially unsaturated 3- to 7-membered ring structure containing one to four heteroatoms, such as nitrogen, oxygen, and sulfur. The designation “C3-C7” indicates that the heterocyclic ring contains a total of from 3 to 7 ring atoms, inclusive of any heteroatoms that occupy a ring atom position. One example of a C3heterocyclyl is aziridinyl. Heterocycles may also be mono-, bi-, or other multi-cyclic ring systems. A heterocycle may be fused to one or more aryl, partially unsaturated, or saturated rings. Heterocyclyl groups include, for example, biotinyl, chromenyl, dihydrofuryl, dihydroindolyl, dihydropyranyl, dihydrothienyl, dithiazolyl, homopiperidinyl, imidazolidinyl, isoquinolyl, isothiazolidinyl, isoxazolidinyl, morpholinyl, oxolanyl, oxazolidinyl, phenoxanthenyl, piperazinyl, piperidinyl, pyranyl, pyrazolidinyl, pyrazolinyl, pyridyl, pyrimidinyl, pyrrolidinyl, pyrrolidin-2-onyl, pyrrolinyl, tetrahydrofuryl, tetrahydroisoquinolyl, tetrahydropyranyl, tetrahydroquinolyl, thiazolidinyl, thiolanyl, thiomorpholinyl, thiopyranyl, xanthenyl, lactones, lactams such as azetidinones and pyrrolidinones, sultams, sultones, and the like. Unless specified otherwise, the heterocyclic ring is optionally substituted at one or more positions with substituents such as alkanoyl, alkoxy, alkyl, alkenyl, alkynyl, amido, amidino, amino, aryl, arylalkyl, azido, carbamate, carbonate, carboxy, cyano, cycloalkyl, ester, ether, formyl, halogen, haloalkyl, heteroaryl, heterocyclyl, hydroxyl, imino, ketone, nitro, phosphate, phosphonato, phosphinato, sulfate, sulfide, sulfonamido, sulfonyl and thiocarbonyl. In certain embodiments, the heterocyclcyl group is not substituted, i.e., it is unsubstituted. [0034] The terms “amine” and “amino” are art-recognized and refer to both unsubstituted and substituted amines, e.g., a moiety represented by the general formula –N(R50)(R51), wherein R50 and R51 each independently represent hydrogen, alkyl, cycloalkyl, heterocyclyl, alkenyl, aryl, aralkyl, or -(CH2)m-R61; or R50 and R51, taken together with the N atom to which they are attached complete a heterocycle having from 4 to 8 atoms in the ring structure; R61 represents an aryl, a cycloalkyl, a cycloalkenyl, a heterocycle or a polycycle; and m is zero or an integer in the range of 1 to 8. In certain embodiments, R50 and R51 each independently represent hydrogen, alkyl, alkenyl, or -(CH2)m-R61. [0035] The terms “alkoxyl” or “alkoxy” are art-recognized and refer to an alkyl group, as defined above, having an oxygen radical attached thereto. Representative alkoxyl groups include methoxy, ethoxy, propyloxy, tert-butoxy and the like. An “ether” is two hydrocarbons covalently linked by an oxygen. Accordingly, the substituent of an alkyl that renders that alkyl an ether is or resembles an alkoxyl, such as may be represented by one of -O-alkyl, -O- alkenyl, -O-alkynyl, -O-(CH2)m-R61, where m and R61 are described above. [0036] The term “amide” or “amido” as used herein refers to a radical of the form -RaC(O)N(Rb)-, -RaC(O)N(Rb)Rc-, -C(O)NRbRc, or -C(O)NH2, wherein Ra, Rb and Rc are each independently alkoxy, alkyl, alkenyl, alkynyl, amide, amino, aryl, arylalkyl, carbamate, cycloalkyl, ester, ether, formyl, halogen, haloalkyl, heteroaryl, heterocyclyl, hydrogen, hydroxyl, ketone, or nitro. The amide can be attached to another group through the carbon, the nitrogen, Rb, Rc, or Ra. The amide also may be cyclic, for example Rb and Rc, Ra and Rb, or Ra and Rc may be joined to form a 3- to 12-membered ring, such as a 3- to 10-membered ring or a 5- to 6- membered ring. [0037] The compounds of the disclosure may contain one or more chiral centers and/or double bonds and, therefore, exist as stereoisomers, such as geometric isomers, enantiomers or diastereomers. The term “stereoisomers” when used herein consist of all geometric isomers, enantiomers or diastereomers. These compounds may be designated by the symbols “R” or “S,” depending on the configuration of substituents around the stereogenic carbon atom. The present invention encompasses various stereoisomers of these compounds and mixtures thereof. Stereoisomers include enantiomers and diastereomers. Mixtures of enantiomers or diastereomers may be designated “(±)” in nomenclature, but the skilled artisan will recognize that a structure may denote a chiral center implicitly. It is understood that graphical depictions of chemical structures, e.g., generic chemical structures, encompass all stereoisomeric forms of the specified compounds, unless indicated otherwise. [0038] As used herein, the terms “subject” and “patient” refer to organisms to be treated by the methods of the present invention. In certain embodiments, such organisms are mammals (e.g., murines, simians, equines, bovines, porcines, canines, felines, and the like), and in some embodiments, such organisms are humans. [0039] As used herein, the term “effective amount” refers to the amount of a compound, composition, or formulation (e.g., a compound, composition, or formulation of the present invention) sufficient to effect beneficial or desired results. As used herein, the term “treating” includes any effect, e.g., lessening, reducing, modulating, ameliorating or eliminating, that results in the improvement of the condition, disease, disorder, and the like, or ameliorating a symptom thereof. [0040] As used herein, the terms “pharmaceutical agent,” “pharmaceutically active agent,” and “drug” are used synonymously and refer to an active agent, making the composition or formulation especially suitable for diagnostic or therapeutic use in vivo or ex vivo. [0041] As used herein, the term “pharmaceutically acceptable carrier” refers to any of the standard pharmaceutical carriers, such as a phosphate buffered saline solution, water, emulsions (e.g., such as an oil/water or water/oil emulsions), and various types of wetting agents. In certain embodiments, the pharmaceutically acceptable carrier is, or comprises, balanced salt solution. The compositions or formulations also can include stabilizers and preservatives. For examples of carriers, stabilizers and adjuvants/excipients, see, e.g., Martin, Remington’s Pharmaceutical Sciences, 15th Ed., Mack Publ. Co., Easton, PA [1975], the disclosure of which is incorporated by reference herein in its entirety. The compositions or formulations may optionally contain a dye. Accordingly, in certain embodiments, the composition or formulation further comprises a dye. [0042] Throughout the description, the molecular weight of a polymer is weight-average molecular weight unless the context clearly indicates otherwise, such as clearly indicating that the molecular weight of the polymer is the number-average molecular weight. [0043] Throughout the description, where compositions or formulations and kits are described as having, including, or comprising specific components, or where processes and methods are described as having, including, or comprising specific steps, it is contemplated that, additionally, there are compositions or formulations and kits of the present invention that consist essentially of, or consist of, the recited components, and that there are processes and methods according to the present invention that consist essentially of, or consist of, the recited processing steps. [0044] As a general matter, compositions or formulations specifying a percentage are by weight unless otherwise specified. Further, if a variable is not accompanied by a definition, then the previous definition of the variable controls. FORMULATIONS FOR FORMING EXTENDED-RELEASE HYDROGELS COMPRISING A PHARMACEUTICALLY ACTIVE AGENT [0045] One aspect of the invention provides an injectable formulation for forming an extended-release hydrogel and delivering a pharmaceutical agent over an extended period of time at the site of interest of a subject, the formulation comprising: (a) a nucleo-functional polymer that is a biocompatible polymer containing a plurality of thio-functional groups -R1-SH wherein R1 is an ester-containing linker; (b) an electro-functional polymer that is a biocompatible polymer containing at least one thiol-reactive group; (c) a pharmaceutical agent; and (d) a liquid pharmaceutically acceptable carrier for administration to the eye of a subject. The formulation can be further characterized by, for example, the identity and structure of the nucleo-functional polymer, the identity and structure of the electro-functional polymer, the identity of the pharmaceutical agent, physical characteristics of the hydrogel formed for controlling the delivery of the pharmaceutical agent, and other features described herein below. In certain embodiments, the site of interest of the subject is the eye and the formulation is an ocular formulation. [0046] The extended-release hydrogel is formed by reaction of the nucleo-functional polymer and electro-functional polymer, and the subsequent uptake of water from the subject (e.g., the subject’s eye or other tissue of interest). In the more specific embodiment of a thiolated poly(vinyl alcohol) polymer as the nucleo-functional polymer and a poly(ethylene glycol) (PEG) containing thiol-reactive groups as the electro-functional polymer, the hydrogel is formed by a cross-linking reaction of thiolated poly(vinyl alcohol) (TPVA) with poly(ethylene glycol) (PEG) containing thiol-reactive groups. The thiolated poly(vinyl alcohol) polymer can be prepared whereby thiol groups are incorporated into poly(vinyl alcohol) (PVA) by coupling thiol functionalities to the hydroxyl groups of the poly(vinyl alcohol), or through use of protected thiol functionalities with subsequent deprotection as described in the literature. Certain poly(ethylene glycol) polymers containing thiol-reactive groups (e.g., an acrylate, methacrylate, maleimidyl, or vinyl-sulfone) may be used in accordance with the invention. Crosslinking of the thiolated poly(vinyl alcohol) and the poly(ethylene glycol) containing thiol-reactive groups occurs through a Michael addition, without use of initiators or an external energy source (e.g., UV light). Features of the Nucleo-functional Polymer [0047] The compositions or formulations for forming an extended-release hydrogel for extended-release of a drug for treatment of various disorders, including ocular disorders, can be characterized according to features of the nucleo-functional polymer. Accordingly, in certain embodiments, the nucleo-functional polymer is a biocompatible polymer comprising poly(vinyl alcohol) containing a plurality of thio-functional groups -R1-SH where, R1 is an ester-containing linker. In certain embodiments, the nucleo-functional polymer is a biocompatible, partially hydrolyzed poly(vinyl alcohol) polymer substituted by a plurality of thio-functional groups -R1- SH. In certain embodiments, the nucleo-functional polymer is a biocompatible, partially hydrolyzed poly(vinyl alcohol) polymer substituted by a plurality of thio-functional groups -R1- SH, wherein the degree of hydrolysis of the partially hydrolyzed poly(vinyl alcohol) polymer is at least 85%. In certain embodiments, the thio-functional group -R1-SH is -OC(O)-(C1-C6 alkylene)-SH. In certain embodiments, the thio-functional group -R1-SH is -OC(O)-(CH2CH2)- SH. [0048] In certain embodiments, the nucleo-functional polymer is a biocompatible poly(vinyl alcohol) polymer comprising:
Figure imgf000032_0001
wherein a is an integer from 1 to about 20 and b is an integer from 1 to about 20. [0049] In certain embodiments, the nucleo-functional polymer is a biocompatible poly(vinyl alcohol) polymer comprising:
Figure imgf000032_0002
wherein a is an integer from 1 to about 20, b is an integer from 1 to about 20, and c is an integer from about 20 to about 500. [0050] The nucleo-functional polymer may be further characterized according to its molecular weight, such as the weight-average molecular weight of the polymer. In certain embodiments, the nucleo-functional polymer has a weight-average molecular weight in the range of from about 4,000 g/mol to about 100,000 g/mol. In certain embodiments, the nucleo- functional polymer has a weight-average molecular weight less than about 75,000 g/mol. In certain embodiments, the nucleo-functional polymer has a weight-average molecular weight in the range of from about 15,000 g/mol to about 25,000 g/mol. In certain embodiments, the nucleo-functional polymer has a weight-average molecular weight of about 19,000 g/mol. [0051] In certain embodiments, the nucleo-functional polymer is a thiolated poly(vinyl alcohol) that has been at least partially hydrolyzed (e.g., hydrolysis of about 75% or more, including all values and ranges from about 75% to about 99.9%). The thiolated poly(vinyl alcohol) may be provided in a solution, dissolved in water or other solvents (including, but not limited to, dimethyl sulfoxide (DMSO) or dimethylformamide (DMF)) at any viable concentration, including at a concentration in the range of about 0.5 wt % to about 25 wt %, including all values and increments therein. [0052] The thiolated poly(vinyl alcohol) can be prepared by reacting a range of thiol containing functional groups with poly(vinyl alcohol), for example, as further described in U.S. Patent Application Publication No.2016/0009872, which is hereby incorporated by reference herein in its entirety. In certain embodiments, thiolated poly(vinyl alcohol) is prepared by reacting (a) a compound having a thiol functionality and at least one hydroxyl-reactive group, such as, for example, a carboxyl group, represented by HS-R-CO2H, where R may include an alkane, unsaturated ether, or ester group, and R includes from 1 to about 20 carbons, with (b) a poly(vinyl alcohol). [0053] In other more specific embodiments, the thiolated poly(vinyl alcohol) comprises the following fragment:
Figure imgf000033_0001
wherein R includes from 1 to about 20 carbons and may be an alkane, saturated ether or ester, and the individual units are randomly distributed along the length of the poly(vinyl alcohol) chain. X is in the range of about 0.1 to about 10%, n is in the range of about 80 to about 99.9%, indicating the level of hydrolysis of the poly(vinyl alcohol) polymer and allowing for water solubility of the polymer and m, the amount of non-hydrolyzed acetate groups, is in the range from about 0.1 to about 20%. [0054] The amount of thiol groups on the poly(vinyl alcohol) can be controlled by the number of hydroxyl groups on the poly(vinyl alcohol) that undergo reaction with the thiolating agent to generate the thiolated poly(vinyl alcohol). In certain embodiments, the amount of thiol functional groups on the poly(vinyl alcohol) may be characterized according to the molar ratio of thiol functional groups to poly(vinyl alcohol) polymer, such as from about 0.1:1 to about 10.0:1, including all values and ranges therein. In certain embodiments, the amount of thiol functional groups is from about 5.0:1 to about 7.0:1, including all values and ranges therein. [0055] More generally, the nucleo-functional polymer containing a plurality of thio- functional groups can be prepared based on procedures described in the literature, such as U.S. Patent Application 2016/0009872, which is hereby incorporated by reference in its entirety, in which a polymer having nucleophilic groups (e.g., hydroxyl groups) is reacted with a thiol- containing compound so that resulting polymer contains a thiol group bound to the polymer backbone via a linker. Features of the Electro-functional Polymer [0056] The compositions or formulations for forming an extended-release hydrogel for extended-release of a drug for treatment of various disorders, including ocular disorders, can be characterized according to the features of the electro-functional polymer. Accordingly, in certain embodiments, the electro-functional polymer is a biocompatible poly(ethylene glycol) polymer substituted by at least one thiol-reactive group. [0057] In certain embodiments, the thiol-reactive group is an alpha-beta unsaturated ester, maleimidyl, or sulfone, each of which is optionally substituted by one or more occurrences of alkyl, aryl, or aralkyl. In certain embodiments, the thiol-reactive group is an alpha-beta unsaturated ester optionally substituted by one or more occurrences of alkyl, aryl, or aralkyl. In certain embodiments, the thiol-reactive group is acrylate
Figure imgf000034_0001
In certain embodiments, the thiol-reactive group is maleimide
Figure imgf000035_0002
. In certain embodiments the, the thiol-
Figure imgf000035_0001
reactive group is vinyl sulfone . [0058] The electro-functional polymer may be further characterized according to its molecular weight, such as the weight-average molecular weight of the polymer. Accordingly, in certain embodiments, the electro-functional polymer has a weight-average molecular weight in the range of from about 500 g/mol to about 100,000 g/mol. In certain embodiments, the electro- functional polymer has a weight-average molecular weight in the range of from about 1,000 g/mol to about 50,000 g/mol. In certain embodiments, the electro-functional polymer has a weight-average molecular weight in the range of from about 2,000 g/mol to about 20,000 g/mol. In certain embodiments, the electro-functional polymer has a weight-average molecular weight less than about 100,000 g/mol. In certain embodiments, the electro-functional polymer has a weight-average molecular weight in the range of from about 2,700 g/mol to about 3,300 g/mol. In certain embodiments, the electro-functional polymer has a weight-average molecular weight in the range of from about 9,000 g/mol to about 11,000 g/mol. In certain embodiments, the electro-functional polymer has a weight-average molecular weight in the range of from about 18,000 g/mol to about 22,000 g/mol. [0059] The electro-functional polymer may be a straight-chain polymer or a branched chain polymer. In yet other embodiments, the electro-functional polymer may be a multi-arm polymer, such as 4-arm polyethylene glycol maleimide, 4-arm polyethylene glycol acrylate, 4-arm polyethylene glycol vinyl sulfone, 8-arm polyethylene glycol maleimide, 8-arm polyethylene glycol acrylate, or 8-arm polyethylene glycol vinyl sulfone or combinations thereof. [0060] In another embodiment, the electro-functional polymer may be a poly(ethylene glycol) end-capped with at least two thiol-reactive groups. The poly(ethylene glycol) may be linear, branched, a dendrimer, or multi-armed. The thiol reactive group may be, for example, an acrylate, methacrylate, maleimidyl, vinyl sulfone, haloacetyl, pyridyldithiol, N- hydroxysuccinimidyl. An exemplary poly(ethylene glycol) end-capped with thiol-reactive groups may be represented by the formula Y-[-O-CH2CH2-]n-O-Y wherein each Y is a thiol- reactive group, and n is, for example, in the range of about 200 to about 20,000. In another embodiment, the electro-functional polymer may be CH2=CHC(O)O-[-CH2CH2-O-]b- C(O)CH=CH2, wherein b is, for example, in the range of about 200 to about 20,000. Alternatively or additionally to the linear embodiments depicted above, the poly(ethylene glycol) may be a dendrimer. For example, the poly(ethylene glycol) may be a 4 to 32 hydroxyl dendron. In further embodiments, the poly(ethylene glycol) may be multi-armed. In such embodiments, the poly(ethylene glycol) may be, for example, 4, 6 or 8 arm and hydroxy-terminated. The molecular weight of the poly(ethylene glycol) may be varied, and in some cases one of the thiol- reactive groups may be replaced with other structures to form dangling chains, rather than crosslinks. In certain embodiments, the molecular weight (Mw) is less than about 25,000, including all values and ranges from about 200 to about 20,000, such as about 200 to about 1,000, about 1,000 to about 10,000, etc. In addition, the degree of functionality may be varied, meaning that the poly(ethylene glycol) may be mono-functional, di-functional or multi- functional. [0061] More generally, the electro-functional polymer can be purchased from commercial sources or prepared based on procedures described in the literature, such as by treating a nucleo- functional polymer with reagent(s) to install one or more electrophilic groups (e.g., by reacting polyethylene glycol with acrylic acid in an esterification reaction to form polyethylene glycol diacrylate, using procedures described in U.S. Pat. No.6,828,401, which is incorporated by reference herein in its entirety, to form polyethylene glycol-maleimide, and using methods described in Lutolf, et al., “Synthetic matrix metalloproteinase-sensitive hydrogels for the conduction of tissue regeneration: engineering cell-invasion characteristics,” Proc. Natl. Acad. Sci. U. S. A. (2003), which is incorporated by reference herein in its entirety, to form polyethylene glycol-vinyl sulfone by coupling PEG-OH with an excess of divinyl sulfone). Relative Amount of Nucleo-functional Polymer and Electro-functional Polymer [0062] The compositions or formulations for forming an extended-release hydrogel for extended-release of a drug for treatment of various disorders, including ocular disorders, can be characterized according to the relative amount of nucleo-functional polymer and electro- functional polymer used. Accordingly, in certain embodiments, the mole ratio of (i) thio- functional groups -R1-SH to (ii) thiol-reactive group is in the range of about 10:1 to about 1:10. In certain embodiments, the mole ratio of (i) thio-functional groups -R1-SH to (ii) thiol-reactive groups is in the range of about 2:1 to about 1:2. In some embodiments the mole ratio of (i) thio- functional groups -R1-SH to (ii) thiol-reactive groups is in the range of about 0.8:1 to about 1.2:1. [0063] Once combined, the combination of the nucleo-functional polymer and the electro- functional polymer in certain embodiments are present in solution in the range of about 25 mg/mL to about 150 mg/mL, including all values and ranges therein, and in some embodiments are present in solution in the range of about 25 mg/mL to about 100 mg/mL, and in certain embodiments about 90 mg/mL. Features of the Extended-Release Hydrogel System Administration of the Formulations to Form an Extended-Release Hydrogel [0064] The compositions or formulations for forming an extended-release hydrogel for extended-release of a drug for treatment of various disorders, including ocular disorders, can be characterized according to the features of administration. Accordingly, in certain embodiments, the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered through topical, epidermal, subdermal, intra-adipose, intramuscular, intra- peritoneal, intravenous, intra-arterial, intracranial, intranasal, and/or intrauterine administration. In some embodiments, the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered through injection. The nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered to any site of a subject where it is desired and appropriate to provide an extended-release hydrogel. In certain embodiments, the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered to the eye of a subject (e.g., by injection). In some embodiments, the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered into the air-filled void within the posterior cavity of the eye of a subject following a vitrectomy. In certain embodiments, the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered in a manner as to fill or partially fill the air-filled void remaining in the eye of a subject following a complete or partial vitrectomy. In either case the amount of formulation that is delivered could be, for example, in a range between about 1 mL to about 6 mL, including all values and ranges therein. [0065] In some embodiments, the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered as a single formulation (e.g., the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent are mixed prior to administration). In certain embodiments, the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered as two or more separate formulations that can mix at the target site of the subject to form the hydrogel. In certain embodiments, the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered as two or more separate formulations that mix within the delivery device to form the extended-release hydrogel as the mixture exits the device. In some embodiments, the pharmaceutical agent is included in a formulation comprising the nucleo-functional polymer prior to administration. In certain embodiment the pharmaceutical agent is included in a formulation comprising the electro-functional polymer prior to administration. In certain embodiment the pharmaceutical agent is included in a formulation comprising the electro- functional polymer and in a formulation comprising the nucleo-functional polymer prior to administration. In certain embodiments, the pharmaceutical agent is included in a formulation comprising both the nucleo-functional polymer and the electro-functional polymer prior to administration. Transmittance of the Extended-Release Hydrogel [0066] The extended-release hydrogel can be characterized by the transmittance of the hydrogel. Hydrogels to be used in various sites of a subject, for example in the eye, for extended release of drugs may require that the hydrogel be optically clear with transparency of at least about 80% for light in the visible spectrum when measured through a hydrogel having a thickness of 2 cm. In certain embodiments, the hydrogel has a transparency of at least about 85% for light in the visible spectrum when measured through hydrogel having a thickness of 2 cm. In certain embodiments, the hydrogel has a transparency of at least about 90% for light in the visible spectrum when measured through hydrogel having a thickness of 2 cm. [0067] Generally, in order to reduce scattering and increase transmittance of light, the size of the particles in the hydrogel must be less than about the wavelength of visible light, therefore in certain embodiments the size of any particle form of a pharmaceutical agent in the hydrogel should be less than about 400 nm. In certain embodiments, the size of the particle form of a pharmaceutical agent in the hydrogel is between about 25 nm and about 200 nm including all ranges therein. In some embodiments the size is between about 50 nm and about 100 nm. [0068] For use in the eye it is important to ensure adequate transmittance, for example, greater than about 80%, and the concentration of pharmaceutical agent particles and their size can impact transmittance. In certain embodiments for use in the eye, the concentration of 50 nM pharmaceutical agent particles is between about 0.025% and about 0.001%, including all ranges therein. Crosslink Time of the Polymers to Form the Extended-Release Hydrogel [0069] The compositions or formulations for delivery of an extended-release hydrogel to a target site of a subject, for example the eye, can be characterized by the crosslink time of the polymers in the formulation (i.e., how long it takes for the hydrogel to form once the nucleo- functional polymer has been combined with the electro-functional polymer). For delivery to various target sites in a subject, for example the eye following vitrectomy, crosslink time should be less than about 10 minutes so that the patient does not need to remain in the surgical position for too long after administration. In certain embodiments, the crosslink time of the disclosed extended-release hydrogels is less than about 7 minutes, when measured at 37°C, and in some embodiments is less than about 5 minutes, when measured at 37°C. In certain embodiments, the crosslink time of the disclosed extended-release hydrogels is less than about 3 minutes, when measured at 37°C, and in some embodiments is less than about 1 minute. Administration of the Formulation to the Eye [0070] The compositions or formulations for forming an extended-release hydrogel for treatment of ocular disorders can be further characterized according to the features of administration. Accordingly, in certain embodiments, the nucleo-functional polymer, electro- functional polymer and pharmaceutical agent may be administered as an injection into the eye (e.g., the vitreous) without performing a vitrectomy. In certain embodiments, the nucleo- functional polymer, electro-functional polymer and pharmaceutical agent may be administered as an intravitreal injection. In the case of intravitreal injection, the amount of formulation that is delivered in certain embodiments is between about 25 μL to about 500 μL, including all values and ranges therein and in certain embodiments between about 50 μL and 200 μL. In some embodiments, the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered as a single formulation to the eye. In certain embodiments, the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered as two or more separate formulations that can mix at the target site (e.g., the vitreous cavity of the eye) to form the extended-release hydrogel. In certain embodiments, the nucleo-functional polymer, electro-functional polymer and pharmaceutical agent may be administered as two or more separate formulations that mix within the delivery device to form the extended-release hydrogel as the mixture exits the device. In certain embodiments, the two separate formulations combine and mix within the injection cannula of a delivery device. The injection cannula device may have a mixing chamber that tapers into a small gauge needle that allows for entry into the eye. In some embodiments, the pharmaceutical agent is included in a formulation comprising the nucleo-functional polymer prior to administration. In certain embodiment the pharmaceutical agent is included in a formulation comprising the electro- functional polymer prior to administration. In some embodiments, the pharmaceutical agent is included in a formulation comprising the nucleo-functional polymer and in a formulation comprising the electro-functional polymer prior to administration. In certain embodiments, the pharmaceutical agent is included in a formulation comprising both the nucleo-functional polymer and the electro-functional polymer prior to administration. Crosslink Time of the Polymers for Forming an Extended-Release Hydrogel in the Eye [0071] The compositions or formulations for delivery to the eye (e.g., as an intravitreal injection) can also be characterized by the crosslink time of the polymers to form the extended- release hydrogel. For delivery to the eye (e.g., as an intravitreal injection), in certain embodiments it is desirable for composition to form a solid hydrogel quickly to avoid diffusion from the site of injection and to ensure a consistent shape/form factor of the extended-release hydrogel. In certain embodiments, the crosslink time of the extended-release hydrogels described herein is less than about 30 seconds after combining the nucleo-functional polymer with the electro-functional polymer, when measured at 37°C. In certain embodiments the crosslink time is less than about 20 seconds after combining the nucleo-functional polymer with the electro-functional polymer, when measured at 37°C, and in some embodiments the crosslink time is less than about 10 seconds after combining the nucleo-functional polymer with the electro-functional polymer, when measured at 37°C. In certain embodiments, the crosslink time of the hydrogels described herein is less than about 5 seconds, less than about 3 seconds, less than about 2 seconds, or less than about 1 second after combining the nucleo-functional polymer with the electro-functional polymer, when measured at 37°C. Ocular-Specific Formulation Considerations [0072] A major risk with the use of products administered to the eye (e.g., intravitreally- administered products) is the risk of a sterile inflammatory reaction due to unacceptably high levels of endotoxin. (Wang, et al., "Acute intraocular inflammation caused by endotoxin after intravitreal injection of counterfeit bevacizumab in Shanghai, China," Ophthalmology 120(2):355-61 (2013)) The ocular environment is particularly sensitive to endotoxins and sterile inflammatory reactions can be seen with formulations not specifically developed for intravitreal use. (Marticorena, et al., "Sterile endophthalmitis after intravitreal injections," Mediators Inflamm.2012:928123 (2012)) In certain embodiments, the compositions and formulations described herein comprise less than or equal to about 0.2 endotoxin units (EU)/mL, a limit even lower than ISO standards 15798 & 11979-8 which recommend no more than (NMT) 0.5 EU/ml. In some embodiments, the compositions and formulations described herein comprises less than or equal to about 0.5 endotoxin units (EU)/mL. In addition, safety concerns of using unbuffered saline as a vehicle for intravitreal injection have been raised in the literature. Intravitreal injection of normal saline has been observed to induce vacuoles in the photoreceptor outer segments and RPE cells, as well as upregulation of inflammatory mediators including TNF-Į, IL- 1ȕ, IL-6, and VEGF. These histopathological and cytokine markers have not been observed in mouse eyes that were injected with phosphate buffered vehicle (PBS) (Hombrebueno, et al., "Intravitreal Injection of Normal Saline Induces Retinal Degeneration in the C57BL/6J Mouse," Transl Vis Sci Technol.3(2):3 (2014)), which in certain embodiments is the vehicle used for administration of the formulations described herein. Features of the Pharmaceutical Agent [0073] The extended-release hydrogel formed by the formulations described herein may act as a drug depot that may be used to deliver various pharmaceutical agents over an extended period of time. The pharmaceutical agents that may be use in the formulations and extended- release hydrogels described herein include anti-inflammatory agents, steroids, NSAIDS, intraocular pressure lowering drugs, antibiotics, pain relievers, inhibitors of vascular endothelial growth factor (VEGF), inhibitors of abnormal vascular growth or vascular leakage, inhibitors of abnormal cell proliferation, chemotherapeutics, anti-viral drugs, gene therapy viral vectors, etc., and combinations thereof. The pharmaceutical agents may be small molecules, proteins, DNA/RNA fragments, glycosaminoglycans, carbohydrates, nucleic acid, inorganic and organic biologically active compounds or other configurations, active portions of any of the proceeding molecules, and combinations thereof. The pharmaceutical agent may be soluble or non-soluble, or combinations thereof in the pharmaceutically acceptable carrier. The pharmaceutical agent may be dissolved in the composition or formulation, suspended as particles, encapsulated in particles (e.g., liposomes, amphiphilic polymer or solid polymer particles) and suspended, or dissolved or suspended in the formulation as an ionic complex (for example a protein- carbohydrate complex) and combinations thereof. In some embodiments, the formulations and/or extended-release hydrogel comprises more than one pharmaceutical agent. In certain embodiments, one or more pharmaceutical agent is included in the formulation comprising the nucleo-functional polymer. In certain embodiments, one or more pharmaceutical agent is included in the formulation comprising the electro-functional polymer. In certain embodiments, one or more pharmaceutical agent is included in the formulation comprising the nucleo- functional polymer and in the formulation comprising the electro-functional polymer. In some embodiments, one or more pharmaceutical agents is included in a formulation comprising both the nucleo-functional polymer and the electro-functional polymer. Features of the Extended-Release Hydrogel For Controlling Drug Delivery [0074] The compositions or formulations for forming an extended-release hydrogel for extended-release of a drug for the treatment of various disorders, including ocular disorders, can be further characterized according to the features of the extended-release hydrogel that control the release of the pharmaceutical agent into the local environment. Features of the extended- release hydrogel formulation for controlling the release of the pharmaceutical agent include: crosslink density or porosity, biodegradation rate, and a combination thereof. Crosslink density or porosity of the extended-release hydrogel [0075] Following the administration of the composition or formulation comprising a nucleo- functional polymer, an electro-functional polymer and one or more pharmaceutical agents within the target site (e.g., the eye), the one or more pharmaceutical agents will diffuse out of the extended-release hydrogel into the surrounding environment. The crosslink density of the resultant extended-release hydrogel acts as a barrier to the diffusion of the one or more pharmaceutical agents within the hydrogel. A higher crosslink density results in a smaller pore size (i.e., distance between crosslinks). If the pore size is close to or less than the hydrodynamic radius of the pharmaceutical agent, then diffusion of the agent will be impeded and release from the hydrogel will be delayed. The crosslinking density of the extended-release hydrogel can be controlled by the molecular weight of the nucleo-functional and electro-functional polymers and the number of functional groups present on each polymer. A lower molecular weight between crosslinks will yield a higher crosslinking density as compared to a higher molecular weight. As previously described, in certain embodiments, the nucleo-functional polymer has a weight- average molecular weight in the range of from about 4,000 g/mol to about 100,000 g/mol and the electro-functional polymer has a molecular weight in the range of from about 500 g/mol to about 100,000 g/mol. Similarly, the molecular weight of each arm in a multi-arm electro-functional polymer has an impact on the porosity of the extended-release hydrogel. Therefore, a multi-arm electro-functional polymer with a lower molecular weight has a higher crosslink density and smaller pore size than a higher molecular weight multi-arm polymer. [0076] The crosslinking density may also be controlled by the concentrations of the nucleo- functional polymer and the electro-functional polymer. Increasing the total concentration increases the cross-linking density as the likelihood or probability that an electro-functional group will combine with a nucleo-functional group and form a crosslink increases. Crosslink density may also be controlled by adjusting the relative amount of nucleo-functional polymer and electro-functional polymer used. A molar ratio of thio-functional groups to thiol-reactive groups of about 1:1 leads to the highest crosslink density. Degradation Rate of the Extended-Release Hydrogel [0077] The length of time over which the one or more pharmaceutical agents can be delivered within the target site (e.g., the eye) and surrounding environment is also a function of the length of time the extended-release hydrogel is present within the site, i.e., degradation rate or degradation time of the extended-release hydrogel. Degradation rate or time can be thought of as the rate or length of time it takes for the extended-release hydrogel to be completely in solution, i.e., for no solid mass to remain or be observed. In certain embodiments, degradation rate or time can be measured by placing the extended-release hydrogel in a solution of PBS and assaying for the presence of the extended-release hydrogel (solid mass) over time. Degradation rate or time may also be measured at different temperatures (e.g., 37°C or 60°C) with higher temperature leading to a faster degradation rate and faster time to complete degradation. In certain embodiments, the degradation time of the extended-release hydrogels described herein is greater than or equal to about 20, 40, 60, 69, 80, 90, 94, 100, 120, 140, or 158 days at 37°C. In some embodiments, the degradation time of the extended-release hydrogels described herein is greater than or equal to about 3, 5, 8, 10, 14, 19, 20, 25, 30, or 32 days at 60° C. PHARMACEUTICAL COMPOSITIONS OR FORMULATIONS [0078] One aspect of the invention provides pharmaceutical compositions or formulations. In certain embodiments, the pharmaceutical composition or formulation comprises (i) a nucleo- functional polymer; (ii) a pharmaceutical agent; and (iii) a pharmaceutically acceptable carrier for administration to the desired target site. In some embodiments, the pharmaceutical composition or formulation comprises (i) an electro-functional polymer; (ii) a pharmaceutical agent; and (iii) a pharmaceutically acceptable carrier for administration to the desired target site. In certain embodiments, the pharmaceutical composition or formulation comprises (i) a nucleo- functional polymer; (ii) an electro-functional polymer; (iii) a pharmaceutical agent; and (iv) a pharmaceutically acceptable carrier for administration to the desired target site. In some embodiments, the target site is the eye of a subject. In certain embodiments, the target site is the eye of a human. In some embodiments, the pharmaceutical composition or formulation is a liquid pharmaceutical composition or composition. In certain embodiments, the pharmaceutical composition or formulation is a lyophilized pharmaceutical composition or formulation. In some embodiments, the pharmaceutically acceptable carrier is PBS, water, or a combination thereof. [0079] In certain embodiments, the pharmaceutical composition or formulation is sterile and may optionally comprise a preservative, antioxidant, and/or other excipients. Exemplary excipients include, for example, acacia, agar, alginic acid, bentonite, carbomers, carboxymethylcellulose calcium, carboxymethylcellulose sodium, carrageenan, ceratonia, cetostearyl alcohol, chitosan, colloidal silicon dioxide, cyclomethicone, cyclo-dextrin, ethylcellulose, gelatin, glycerin, glyceryl behenate, guar gum, hectorite, hydrogenated vegetable oil type I, hydroxyethyl cellulose, hydroxyethylmethyl cellulose, hydroxypropyl cellulose, hydroxypropyl starch, hypromellose, hyaluronic acid, magnesium aluminum silicate, maltodextrin, methylcellulose, polydextrose, polyethylene glycol, poly(methylvinyl ether/maleic anhydride), polyvinyl acetate phthalate, polyvinyl alcohol, potassium chloride, povidone, propylene glycol alginate, saponite, sodium alginate, sodium chloride, stearyl alcohol, sucrose, sulfobutylether (3-cyclodextrin, tragacanth, trehalose, xanthan gum, and derivatives and mixtures thereof. In some embodiments, the excipient is a bioadhesive or comprises a bioadhesive polymer. [0080] In some embodiments, the concentration of the excipient in the pharmaceutical composition or formulation ranges from about 0.1 to about 20% by weight. In certain embodiments, the concentration of the excipient in the pharmaceutical composition or formulation ranges from about 5 to about 20% by weight. In certain embodiments, the concentration of the excipient in the pharmaceutical composition or formulation is less than about 20%, less than about 15%, less than about 10%, less than about 9%, less than about 8%, less than about 7%, less than about 6%, less than about 5%), less than about 4%, less than about 3%, less than about 2%, less than about 1.8%, less than about 1.6%, less than about 1.5%, less than about 1.4%, less than about 1.2%, less than about 1%, less than about 0.9%, less than about 0.8%, less than about 0.7%, less than about 0.6%, less than about 0.5%, less than about 0.4%, less than about 0.3%, less than about 0.2%, or less than about 0.1% by weight. [0081] The pharmaceutical composition or formulation may be further characterized according to its viscosity. In certain embodiments, the viscosity of the pharmaceutical composition is less than about 4000 cP, less than about 2000 cP, less than about 1000 cP, less than about 800 cP, less than about 600 cP, less than about 500 cP, less than about 400 cP, less than about 200 cP, less than about 100 cP, less than about 80 cP, less than about 60 cP, less than about 50 cP, less than about 40 cP, less than about 20 cP, less than about 10 cP, less than about 8 cP, less than about 6 cP, less than about 5 cP, less than about 4 cP, less than about 3 cP, less than about 2 cP, less than about 1 cP. In some embodiments, the viscosity of the pharmaceutical composition or formulation is at least about 4,000 cP, at least about 2,000 cP, at least about 1,000 cP, at least about 800 cP, at least about 600 cP, at least about 500 cP, at least about 400 cP, at least about 200 cP, at least about 100 cP, at least about 80 cP, at least about 60 cP, at least about 50 cP, at least about 40 cP, at least about 20 cP, at least about 10 cP, at least about 8 cP, at least about 6 cP, at least about 5 cP, at least about 4 cP, at least about 3 cP, at least about 2 cP, at least about 1 cP. In certain embodiments, the viscosity of the pharmaceutical composition or formulation is about 4,000 cP, about 2,000 cP, about 1,000 cP, about 800 cP, about 600 cP, about 500 cP, about 400 cP, about 200 cP, about 100 cP, about 80 cP, about 60 cP, about 50 cP, about 40 cP, about 20 cP, about 10 cP, about 8 cP, about 6 cP, about 5 cP, about 4 cP, about 3 cP, about 2 cP, about 1 cP. In some embodiments, the viscosity of the pharmaceutical composition or formulation is between about 5 cP and about 50 cP. [0082] In some embodiments, the pharmaceutical composition or formulation may be further characterized according to its pH. In certain embodiments, the pharmaceutical composition or formulation has a pH in the range of from about 5 to about 9, or about 6 to about 8. In certain embodiments, the pharmaceutical composition or formulation has a pH in the range of from about 6.5 to about 7.5. In certain embodiments, the pharmaceutical composition or formulation has a pH of about 7. [0083] In certain embodiments, the pharmaceutical composition or formulation comprises water, and the composition or formulation has a pH in the range of about 7.1 to about 7.7. In certain embodiments, the pharmaceutical composition or formulation comprises water, and the composition or formulation has a pH in the range of about 7.1 to about 7.6, about 7.1 to about 7.5, about 7.1 to about 7.4, about 7.2 to about 7.6, about 7.2 to about 7.5, about 7.2 to about 7.4, about 7.2 to about 7.3, about 7.3 to about 7.7, about 7.3 to about 7.6, about 7.3 to about 7.5, about 7.3 to about 7.4, about 7.4 to about 7.7, about 7.4 to about 7.6, or about 7.4 to about 7.5. In certain embodiments, the pharmaceutical composition or formulation comprises water, and the composition or formulation has a pH in the range of about 7.3 to about 7.5. In certain embodiments, the pharmaceutical composition or formulation comprises water, and the composition or formulation has a pH of about 7.4. [0084] The pharmaceutical composition or formulation may be further characterized according to its osmolality and the presence and/or identity of salts. For example, in certain embodiments, the pharmaceutical composition or formulation has an osmolality in the range of about 200 mOsm / kg to about 400 mOsm / kg. In certain embodiments, the pharmaceutical composition or formulation has an osmolality in the range of about 250 mOsm / kg to about 350 mOsm / kg. In certain embodiments, the pharmaceutical composition or formulation has an osmolality in the range of about 280 mOsm / kg to about 320 mOsm / kg. In certain embodiments, the pharmaceutical composition or formulation has an osmolality of about 300 mOsm / kg. In certain embodiments, the pharmaceutical composition or formulation further comprises an alkali metal salt. In certain embodiments, the pharmaceutical composition or formulation further comprises an alkali metal halide salt, an alkaline earth metal halide salt, or a combination thereof. In certain embodiments, the pharmaceutical composition or formulation further comprises sodium chloride. In certain embodiments, the pharmaceutical composition or formulation further comprises sodium chloride, potassium chloride, calcium chloride, magnesium chloride, or a combination of two or more of the foregoing. In certain embodiments, the pharmaceutical composition or formulation comprises phosphate buffered saline (PBS). In some embodiments, the PBS comprises one or more of sodium chloride, potassium chloride, sodium phosphate and potassium phosphate. [0085] The pharmaceutical composition or formulation may be further characterized according to the level of endotoxins present in the composition or formulation. In certain embodiments, the composition or formulation has an endotoxin level of less than about 20 endotoxin units/ml, less than about 15 endotoxin units/ml, less than about 10 endotoxin units/ml, less than about 5 endotoxin units/ml, less than about 2.5 endotoxin units/ml, less than about 1.0 endotoxin units/ml, less than about 0.8 endotoxin units/ml, less than about 0.5 endotoxin units/ml, less than about 0.2 endotoxin units/ml, or less than about 0.1 endotoxin units/ml. [0086] The pharmaceutical composition or formulation may also be characterized by the size and number of any particles, including any drug particles, present in the composition or formulation. In certain embodiments, the composition or formulation has less than about 50 particles per mL with a size of ^ 10 μm. In some embodiments, the composition or formulation has less than about 5 particles per mL with a size of ^ 25 μm. KITS FOR USE IN MEDICAL APPLICATIONS [0087] Another aspect of the invention provides a kit for treating a disorder. In certain embodiments, the kit comprises: i) a formulation comprising a nucleo-functional polymer and a pharmaceutical agent and ii) a formulation comprising an electro-functional polymer. In some embodiments, the kit comprises: i) a formulation comprising a nucleo-functional polymer and ii) a formulation comprising an electro-functional polymer and a pharmaceutical agent. In some embodiments, the kit comprises: i) a formulation comprising a nucleo-functional polymer and a pharmaceutical agent and ii) a formulation comprising an electro-functional polymer and a pharmaceutical agent. In certain embodiments, the kit comprises: i) a formulation comprising a nucleo-functional polymer; ii) a formulation comprising a pharmaceutical agent, and iii) a formulation comprising an electro-functional polymer. In some embodiments one or more the formulations provided in the kit comprises a pharmaceutically acceptable carrier. In certain embodiments, the pharmaceutically acceptable carrier comprises PBS. In some embodiments, the kit further comprises instructions for administering the formulations to a target site of interest in a subject, for example, the eye of a subject. In some embodiments, the kit further comprises the components and/or accessories required to prepare and administer the formulations to a target site of interest in a subject, for example the eye of a subject. [0088] The description above describes multiple aspects and embodiments of the invention. The patent application specifically contemplates all combinations and permutations of the aspects and embodiments. EXAMPLES [0089] The following examples are included merely for purposes of illustration of certain aspects and embodiments of the present invention, and are not intended to limit the invention. EXAMPLE 1A – EFFECT OF THIOL-REACTIVE GROUP ON DEGRADATION AND CROSSLINK TIME OF HYDROGELS [0090] Hydrogels were prepared from formulations that resulted from combining thiolated poly(vinyl alcohol) (tPVA), with polyethylene glycol polymers having varying thiol-reactive groups and structures. The tPVA and PEG-based thiol reactive polymers were separately dissolved in phosphate buffered saline (PBS) at a concentration of 6%. Equal volumes of the tPVA and PEG solutions were combined into a formulation and allowed to react at ambient temperatures (20-22°C). Crosslink time of the polymers was measured by the time required for a 1.9 mm x 8 mm magnetic stir bar spinning at 100 rpm immersed within the formulation to stop spinning. Degradation time of the hydrogel was determined by placing 1 mg hydrogel samples in 10 mL of PBS at either 60°C or 37°C. Samples were observed and PBS was changed daily. Degradation time was defined as the day that the hydrogel sample was completely in solution, i.e., no solid mass was observed. Results are summarized in Table 1A. Table 1A. Crosslink Time and Degradation Time for Hydrogels Formed from Formulations with Varying Thiol-reactive End-groups
Figure imgf000048_0001
Figure imgf000049_0001
EXAMPLE 1B – EFFECT OF THIOL-REACTIVE GROUP ON HYDROGEL DEGRADATION [0091] Hydrogels were prepared by combining a formulation comprising thiolated poly (vinyl alcohol) (tPVA) with formulations comprising polyethylene glycol polymers having varying thiol-reactive groups and structures. The tPVA and PEG-based thiol reactive polymers were separately dissolved in phosphate buffered saline (PBS) at a concentration of 6% (tPVA) and 12% (thiol-reactive polymer). Equal volumes of the tPVA and PEG solutions were combined into a formulation and allowed to react at ambient temperature (20-22°C). Degradation time was determined by placing 1 mg hydrogel samples in 10 mL of PBS at 60°C. Samples were observed and PBS was changed daily. Degradation time was defined as the day that the hydrogel sample was completely in solution, i.e., no solid mass was observed. Degradation time at 37°C was calculated as follows: tr/ta=2^((Ta-Tr)/10) tr: degradation time at real temperature ta: degradation time at accelerated test temperature Tr: real temperature Ta: accelerated test temperature [0092] Results are summarized in Table 1B. Table 1B. Degradation Time for Hydrogels Formed from Formulations with Varying Thiol-reactive End-groups
Figure imgf000049_0002
EXAMPLE 2 – EFFECT OF VARYING HYDROGEL COMPOSITION ON CROSSLINK DENSITY/PORE SIZE [0093] For extended-release of a large molecule such as a protein, the pore size of the extended-release hydrogel should be close to or smaller than the hydrodynamic radius of the molecule. The pore size of the hydrogel is determined by the distance between crosslinks or the crosslink density; the higher the crosslink density, the smaller the pore size. The pore size of a hydrogel can be evaluated by measuring the diffusion of dextran having varying hydrodynamic radii within the hydrogel. [0094] Hydrogels were prepared from a formulation comprising thiolated poly(vinyl alcohol) (tPVA) and polyethylene glycol acrylate polymers having varying molecular weights and structures (i.e., single and multi-arm). The tPVA and PEG-acrylate polymers were separately dissolved in phosphate buffered saline (PBS) at varying concentrations. Equal volumes of the tPVA and PEG-acrylate solutions were combined into a formulation and allowed to react at ambient temperatures (20-22°C). [0095] The amount of fluorescently labeled Dextran released from the hydrogels over 24 hours was determined. (Liao, et. al., “Influence of hydrogel mechanical properties and mesh size on vocal fold fibroblast extracellular matrix production and phenotype,” Acta Biomaterialia 4:1161–1171 (2008)) Dextrans (Molecular weight 20 kDa, 40 kDa, 75 kDa and 150 kDa) labeled with fluorescein isothiocyanate (FITC-Dextran) were dissolved in water at 10 mg/mL. Hydrogel samples were placed in test tubes and a FITC-Dextran solution was added to the tubes. The FITC-Dextran was allowed to diffuse into the hydrogels for 24 hours at 37°C. The FITC- Dextran-containing hydrogels were removed and placed in test tubes with fresh PBS to allow the FITC-Dextran to diffuse out of the hydrogel. After 24 hours, the fluorescence of the PBS solution was measured and the amount of dextran released was calculated. Results are summarized in Table 2. Table 2. Diffused FITC-Dextran for Hydrogels with Varying Composition
Figure imgf000050_0001
Figure imgf000051_0001
[0096] In this example, the amount of diffused FITC-Dextran is lowest for the hydrogel formed using the 1:1 ratio of 6% tPVA:12% 4-arm PEG Acrylate formulation. Therefore, this formulation has the smallest hydrogel pore size of those shown in Table 2. EXAMPLE 3 - FITC-DEXTRAN INCORPORATION AND RELEASE FROM HYDROGELS [0097] Hydrogels were prepared from formulations comprising thiolated poly(vinyl alcohol) (tPVA) and polyethylene glycol polymers having varying thiol-reactive groups and structures. tPVA was dissolved in 1 mL phosphate buffered saline (PBS) at a concentration of 6%. FITC- Dextran (70 kDa) was dissolved in 1 mL PBS at a concentration of 22.5 mg/mL. The PEG-thiol reactive polymer was dissolved in the FITC-Dextran/PBS solution at a concentration of 12%. Equal 1 mL volumes of the tPVA and PEG/Dextran solutions were combined and allowed to react at ambient temperatures (20-22° C). After suitable reaction time, a 1.2 g sample of each Dextran-loaded hydrogel (~ 13.5 mg FITC Dextran/sample) was placed in a dialysis tube. 2 mL of PBS was added to the inside of the tube and the tube placed in a container with 30 mL of PBS. Containers were placed in an incubator at 37°C. The PBS in the container was sampled periodically and its florescence measured to determine the amount of FITC-Dextran released from the hydrogel. The PBS in the container was replaced after sampling to ensure sink conditions were maintained throughout the study. [0098] Three hydrogel formulations were evaluated: 6% tPVA:6% PEG Diacrylate (6% PEGDA), 6% tPVA:12% 4-arm PEG Acrylate (12% PEGTA), and 6% tPVA:12% 4-arm PEG Vinyl sulfone (12% PEG-4VS). The results of the release studies are shown in Figure 1. Complete release of the Dextran was observed at ~21 days for the 6% PEGDA hydrogel, ~44 days for the 12% PEGTA hydrogel, and ~ 80 Days for the 12% PEG-4VS hydrogel. EXAMPLE 4 - DEXTRAN INCORPORATION AND RELEASE FROM TPVA: PEG-MALEIMIDE HYDROGEL [0099] Hydrogels were prepared from formulations containing thiolated poly(vinyl alcohol) (tPVA), with 4-arm polyethylene glycol maleimide. tPVA was dissolved in 1 mL phosphate buffered saline (PBS) at a concentration of 6%. FITC-Dextran (70 kDa) was dissolved in 1 mL PBS at a concentration of 22.5 mg/mL. The 4-arm PEG maleimide polymer was dissolved in the FITC-Dextran/PBS solution at a concentration of 12%. Equal 1 mL volumes of the tPVA and PEG/Dextran solutions were placed in separate barrels of a dual barrel syringe. A mixing tip was attached to the end of the dual barrel syringe and the two solutions were injected through the mixing tip simultaneously. The polymers crosslinked as they combined within the mixing tip (i.e., within seconds) forming a firm hydrogel exiting the mixing tip. A 1.2 g sample of each Dextran-loaded hydrogel was placed in a dialysis tube. 2 mL of PBS was added to the inside of the tube and the tube placed in a container with 30 mL of PBS. Containers were placed in an incubator at 37°C. The PBS in the container was sampled periodically and its fluorescence measured to determine the amount of FITC-Dextran released from the hydrogel. The PBS in the container was replaced after sampling to ensure sink conditions were maintained throughout the study. [0100] The results of the release study are shown in Figure 2 as cumulative % release vs. days1/2. The results show a nearly first-order release of the 70 kDa FITC-Dextran from the hydrogel over > 60 days. The results were fit to the equation y = 7.8276x + 14.985 with an R2 = 0.9982. Complete release was calculated from the linear equation to be ~ 120 days. EXAMPLE 5: BEVACIZUMAB INCORPORATION INTO AND RELEASE FROM EXTENDED-RELEASE HYDROGELS [0101] Bevacizumab is an anti-VEGF monoclonal antibody (large protein) with a molecular weight of ~ 150kD that has been found to be a very effective treatment for several back-of-the- eye diseases including age-related macular degeneration (AMD), proliferative diabetic retinopathy, diabetic macular edema, macular edema from retinal vein occlusions and choroidal neovascularization, among others. Intravitreal injection of bevacizumab at a dose of 1.25mg has been well tolerated and shown to provide improvement in visual acuity, decreased retinal thickness and reduction in vascular leakage in many patients. To maintain the improvement in vision, monthly repetitive injections are required to maintain the effective dose of ~ 1 μg/mL in the vitreous. However, when repeated injections are required, there is a high risk of complications such as endophthalmitis, as well as the pain, apprehension and distress associated with inserting needles into eyes. Therefore a delivery method that reduces the need for repetitive injections and extends the therapeutic dose in the vitreous would provide a significant improvement. [0102] Bevacizumab was loaded into tPVA:4-arm PEG vinyl sulfone (PEG-4VS-1, PEG- 4VS-2) and tPVA:4-arm PEG maleimide (PEG-4MAL) hydrogels as described in Examples 3 and 4, respectively. Release studies were performed as described previously. 0.5 g samples with ~6mg bevacizumab were loaded into the dialysis tubes.1 mL of PBS was added to the tubes and the tubes were placed in a container with 30 mL of PBS at 37° C. The amount of bevacizumab released at each time point was determined by measuring the auto-florescence of the protein in the release solutions at 280 nm. [0103] Results of the release studies are shown in Figures 3A and 3B. The concentration of bevacizumab observed in the release media was found to be ~ 2 μg/mL for the tPVA:4-arm PEG vinyl sulfone hydrogel and ~ 1 μg/mL for the tPVA:4-arm PEG maleimide hydrogel. [0104] To confirm that the bevacizumab released from the extended-release hydrogel was still active and able to bind to VEGF, samples from the release solutions for the tPVA:4-arm PEG vinyl sulfone hydrogels were evaluated by an ELISA assay. (Sinapis et.al, “Pharmacokinetics of intravitreal bevacizumab (Avastin®) in rabbits” Clin Ophthalmol.5:697- 704 (2011)). Table 3 shows the results of the ELISA assay compared to the auto-fluorescence results at various time points. Results of both assays were similar at all time points indicating that the bevacizumab was still an active protein after incorporation and release from the extended-release hydrogel. Table 3: Bevacizumab Concentration After Release From tPVA:4 Arm PEG Vinyl sulfone Extended-Release Hydrogel
Figure imgf000054_0001
EXAMPLE 6 – TACROLIMUS ENCAPSULATION INTO AND RELEASE FROM A HYDROGEL [0105] Tacrolimus is a small molecule drug (~ 800 Da) with low solubility in water (~ 1μg/mL). It is an anti-inflammatory drug that may be useful in treating various conditions, including uveitis or other inflammatory conditions of the eye. [0106] Tacrolimus was encapsulated in Soluplus®, a graft co-polymer of polycaprolactam- polyvinyl aetate-polyethylene glycol. Soluplus® is an amphiphilic polymer that self-assembles into nanomicelles in water. Tacrolimus was encapsulated within the hydrophobic core of the nanomicelles as described in Wu, et. al., “Novel self-assembled tacrolimus nanoparticles cross- linking thermosensitive hydrogels for local rheumatoid arthritis therapy” Colloids and Surfaces B: Biointerfaces 14997–104 (2017). Nanoparticles with a size of 70 ±20 nm incorporating ~ 12% tacrolimus by weight were obtained. [0107] Hydrogels were prepared from thiolated poly(vinyl alcohol) (tPVA) and polyethylene glycol diacrylate (PEGDA). tPVA was dissolved in 1 mL phosphate buffered saline (PBS) at a concentration of 6%. 0.25 mL of tacrolimus loaded nanoparticles in deionized water at a concentration of ~8 mg/mL was added to 0.75 mL of PBS. The PEGDA was then dissolved in the 1 mL tacrolimus nanoparticle solution at a concentration of 6%. Equal 1 mL volumes of the tPVA and PEG/tacrolimus solutions were combined and allowed to react at ambient temperatures (20-22° C). The resulting hydrogels were visibly transparent. After suitable reaction time, a 1.25 g sample of each tacrolimus-loaded hydrogel (~ 135 μg tacrolimus/sample) was placed in a dialysis tube. 3 mL of PBS with 0.5% sorbate was added to the inside of the tube and the tube placed in a container with 27 mL of PB with 0.5% sorbate as the release solution. Containers were placed in an incubator at 37°C. The release solution in the container was sampled periodically to determine the amount of tacrolimus released from the hydrogel. The concentration of tacrolimus in the sample was measured using a commercially available ELISA assay. The release solution in the container was replaced after sampling to ensure sink conditions were maintained throughout the study. Results of the release study are shown in Figure 4. The hydrogel was completely degraded by day 21. EXAMPLE 7 – BEVACIZUMAB RELEASE FROM TPVA:PEG-4MAL HYDROGEL [0108] Bevacizumab was loaded into a tPVA:PEG-4MAL hydrogel as follows. Lyophilized tPVA (30 mg) was dissolved in 0.5 mL PBS to create a 6% tPVA solution. Bevacizumab (23.6 mg/mL) was diluted to 4mg/mL in PBS. 0.5 mL of the 4 mg/mL Bevacizumab/PBS solution was added to 60 mg of PEG-4MAL to create a 12% PEG-4MAL solution. Equal 0.5 mL volumes of the tPVA and PEG-4MAL/Bevacizumab solutions were placed in separate barrels of a dual barrel syringe. A mixing tip was attached to the end of the dual barrel syringe and the two solutions were injected through the mixing tip simultaneously into a petri dish. A 0.5 g sample of the formed hydrogel was placed in a dialysis tube.2 mL of PBS was added to the tube and the tube was placed in a container with 30 mL of PBS. The container was placed in an incubator at 37° C. The PBS in the container was sampled periodically and the Bevacizumab concentration measured by ELISA to determine the amount released from the hydrogel. The PBS in the container was replaced after sampling to ensure sink conditions were maintained throughout the study. [0109] The results of the release study are shown in Figure 5. Bevacizumab was found at ug/mL concentrations in the release media for the 116 days duration of the study. The PEG- 4MAL hydrogel was still present at the end of the study. EXAMPLE 8 – INJECTION OF TPVA:PEG-4MAL HYDROGELS WITH AND WITHOUT BEVACIZUMAB INTO A RABBIT EYE [0110] tPVA:PEG-4MAL hydrogels with and without Bevacizumab were injected into rabbit eyes to demonstrate the ability to form a drug depot in the vitreous. [0111] A 6% tPVA solution was prepared by reconstituting 0.24 g lyophilized tPVA with 4 mL PBS. A 12% PEG-4MAL solution was prepared by reconstituting 0.36 g PEG-4MAL with 3 mL PBS. A 6% tPVA/Bevacizumab solution was prepared by reconstituting 0.24g of lyophilized tPVA with 2 mL PBS and 2 mL of Bevacizumab (23.6 mg/mL). [0112] For hydrogels without Bevacizumab, equal 70 μL volumes of 6% tPVA solution and 12% PEG-4MAL solution were loaded into separate 1 mL syringes. The syringes were inserted in a two syringe single use dispenser connected to a luer lock adapter (M-System, Sulzer MedMix) and a 30g low dead space needle (TSK Laboratory). Similarly, for Bevacizumab loaded hydrogels, equal 70 μL volumes of tPVA/Bevacizumab solution and PEG-4MAL solution were loaded into the delivery system. [0113] The 30g needle was inserted through the sclera into the vitreous of a rabbit eye. For each injection, ~140 μL of hydrogel of the combined solution was injected directly into the vitreous. Immediately upon injection the hydrogels formed within the vitreous as small, discrete, generally spherically-shaped deposition. INCORPORATION BY REFERENCE [0114] All of the references cited herein are hereby incorporated by reference in their entireties. EQUIVALENTS [0115] The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The foregoing embodiments are therefore to be considered in all respects illustrative rather than limiting the invention described herein. Scope of the invention is thus indicated by the appended claims rather than by the foregoing description, and all changes that come within the meaning and range of equivalency of the claims are intended to be embraced therein.

Claims

CLAIMS What is claimed is: 1. A formulation for forming an extended-release hydrogel, the formulation comprising: a. a nucleo-functional polymer that is a biocompatible polymer containing a plurality of thio-functional groups -R1-SH wherein R1 is an ester-containing linker; b. an electro-functional polymer that is a biocompatible polymer containing at least one thiol-reactive group; c. a pharmaceutical agent; and d. a pharmaceutically acceptable carrier.
2. The formulation of claim 1, wherein the nucleo-functional polymer comprises a biocompatible poly(vinyl alcohol) polymer substituted by a plurality of thio- functional groups -R1-SH.
3. The formulation of any one of claims 1-2, wherein the electro-functional polymer is a biocompatible polymer comprising poly(ethylene glycol)polymer substituted by at least one thiol-reactive group.
4. The formulation of any one of claims 1-3, wherein the thiol-reactive group is an alpha-beta unsaturated ester, maleimidyl, sulfone, or combinations thereof.
5. The formulation of any one of claims 1-4, wherein the electro-functional polymer comprises a multi-arm polymer.
6. The formulation of claim 5, wherein the multi-arm polymer comprises as 4-arm polyethylene glycol maleimide, 4-arm polyethylene glycol acrylate, 4-arm polyethylene glycol vinyl sulfone, 8-arm polyethylene glycol maleimide, 8-arm polyethylene glycol acrylate, 8-arm polyethylene glycol vinyl sulfone, or combinations thereof.
7. The formulation of any one of claims 1-6, further comprising an alkali metal salt.
8. The formulation of any one of claims 1-7, wherein the formulation has an osmolality in the range of about 200 mOsm / kg to about 400 mOsm / kg.
9. The formulation of any one of claims 1-8, wherein the formulation has an endotoxin level of less than about 20 endotoxin units/ml, less than about 15 endotoxin units/ml, less than about 10 endotoxin units/ml, less than about 5 endotoxin units/ml, less than about 2.5 endotoxin units/ml, less than about 1.0 endotoxin units/ml, less than about 0.8 endotoxin units/ml, less than about 0.5 endotoxin units/ml, less than about 0.2 endotoxin units/ml, or less than about 0.1 endotoxin units/ml.
10. The formulation of any one of claims 1-9, wherein the formulation has less than about 5 particles per mL with a size of ^ 25 μm.
11. The formulation of any one of claims 1-10, wherein the hydrogel formed by the formulation has a crosslink time of less than about 10 minutes, less than about 7 minutes, less than about 5 minutes, less than about 3 minutes, less than about 1 minute, less than about 20 seconds, less than about 10 seconds, less than about 5 seconds, or less than about 1 second when measured at 37°C.
12. The formulation of any one of claims 1-11, wherein the hydrogel formed by the formulation has a degradation time that is greater than or equal to about 3, about 5, about 8, about 10, about 13, about 14, about 15, about 19, or about 32 days at 60°C.
13. The formulation of any one of claims 1-12, wherein the hydrogel formed by the formulation releases the pharmaceutical agent over a period of at least about 5, about 10, about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, about 100, or about 120 days.
14. The formulation of any one of claims 1-13, wherein the formulation has a viscosity of less than about 4000 cP, about 2000 cP, about 1000 cP, about 800 cP, about 600 cP, about 500 cP, about 400 cP, about 200 cP, about 100 cP, about 80 cP, about 60 cP, about 50 cP, about 40 cP, about 20 cP, about 10 cP, about 8 cP, about 6 cP, about 5 cP, about 4 cP, about 3 cP, about 2 cP about 1 cP prior to formation of the hydrogel.
15. The formulation of any one of claims 1-14, wherein the pharmaceutical agent comprises an anti-inflammatory agent, a steroid, an NSAID, an intraocular pressure lowering drug, an antibiotic, a pain reliever, an inhibitor of vascular endothelial growth factor (VEGF), an inhibitor of abnormal vascular growth or vascular leakage, an inhibitor or modifier of the complement pathway, a neuroprotectant, an inhibitor of abnormal cell proliferation, a chemotherapeutic, an anti-viral drug, a gene therapy viral vector, or a combination thereof.
16. The formulation of any one of claims 1-15, wherein the pharmaceutical agent comprises bevacizumab.
17. The formulation of any one of claims 1-16, wherein the formulation is an ocular formulation.
18. A formulation for use in forming an extended-release hydrogel, the formulation comprising: a. a nucleo-functional polymer that is a biocompatible polymer containing a plurality of thio-functional groups -R1-SH wherein R1 is an ester-containing linker; b. a pharmaceutical agent; and c. a pharmaceutically acceptable carrier.
19. The formulation of claim 18, wherein the nucleo-functional polymer comprises a biocompatible poly(vinyl alcohol) polymer substituted by a plurality of thio- functional groups -R1-SH.
20. The formulation of any one of claims 18-19, further comprising an alkali metal salt.
21. The formulation of any one of claims 18-20, wherein the formulation has an osmolality in the range of about 200 mOsm / kg to about 400 mOsm / kg.
22. The formulation of any one of claims 18-21, wherein the formulation has an endotoxin level of less than about 20 endotoxin units/ml, less than about 15 endotoxin units/ml, less than about 10 endotoxin units/ml, less than about 5 endotoxin units/ml, less than about 2.5 endotoxin units/ml, less than about 1.0 endotoxin units/ml, less than about 0.8 endotoxin units/ml, less than about 0.5 endotoxin units/ml, less than about 0.2 endotoxin units/ml, or less than about 0.1 endotoxin units/ml.
23. The formulation of any one of claims 18-22, wherein the formulation has less than about 50 particles per mL with a size of ≥ 10 μm.
24. The formulation of any one of claims 18-23, wherein the formulation has a viscosity of less than about 4000 cP, about 2000 cP, about 1000 cP, about 800 cP, about 600 cP, about 500 cP, about 400 cP, about 200 cP, about 100 cP, about 80 cP, about 60 cP, about 50 cP, about 40 cP, about 20 cP, about 10 cP, about 8 cP, about 6 cP, about 5 cP, about 4 cP, about 3 cP, about 2 cP about 1 cP prior to formation of the hydrogel.
25. The formulation of any one of claims 18-24, wherein the pharmaceutical agent comprises an anti-inflammatory agent, a steroid, an NSAID, an intraocular pressure lowering drug, an antibiotic, a pain reliever, an inhibitor of vascular endothelial growth factor (VEGF), an inhibitor of abnormal vascular growth or vascular leakage, an inhibitor of abnormal cell proliferation, a chemotherapeutic, an anti-viral drug, a gene therapy viral vector, or a combination thereof.
26. The formulation of any one of claims 18-25, wherein the pharmaceutical agent comprises bevacizumab.
27. The formulation of any one of claims 18-26, wherein the formulation is an ocular formulation.
28. A formulation for forming an extended-release hydrogel, the formulation comprising: a. an electro-functional polymer that is a biocompatible polymer containing at least one thiol-reactive group; b. a pharmaceutical agent; and c. a pharmaceutically acceptable carrier.
29. The formulation of claim 28, wherein the electro-functional polymer is a biocompatible polymer comprising poly(ethylene glycol)polymer substituted by at least one thiol-reactive group.
30. The formulation of any one of claims 28-29, wherein the electro-functional polymer comprises a multi-arm polymer.
31. The formulation of any one of claims 28-30, further comprising an alkali metal salt.
32. The formulation of any one of claims 28-31, wherein the formulation has an osmolality in the range of about 200 mOsm / kg to about 400 mOsm / kg.
33. The formulation of any one of claims 28-32, wherein the formulation has an endotoxin level of less than about 20 endotoxin units/ml, less than about 15 endotoxin units/ml, less than about 10 endotoxin units/ml, less than about 5 endotoxin units/ml, less than about 2.5 endotoxin units/ml, less than about 1.0 endotoxin units/ml, less than about 0.8 endotoxin units/ml, less than about 0.5 endotoxin units/ml, less than about 0.2 endotoxin units/ml, or less than about 0.1 endotoxin units/ml.
34. The formulation of any one of claims 28-33, wherein the formulation has less than about 50 particles per mL with a size of ^ 10 μm.
35. The formulation of any one of claims 28-34, wherein the formulation has a viscosity of less than about 4000 cP, about 2000 cP, about 1000 cP, about 800 cP, about 600 cP, about 500 cP, about 400 cP, about 200 cP, about 100 cP, about 80 cP, about 60 cP, about 50 cP, about 40 cP, about 20 cP, about 10 cP, about 8 cP, about 6 cP, about 5 cP, about 4 cP, about 3 cP, about 2 cP about 1 cP prior to formation of the hydrogel.
36. The formulation of any one of claims 28-35, wherein the pharmaceutical agent comprises an anti-inflammatory agent, a steroid, an NSAID, an intraocular pressure lowering drug, an antibiotic, a pain reliever, an inhibitor of vascular endothelial growth factor (VEGF), an inhibitor of abnormal vascular growth or vascular leakage, an inhibitor of abnormal cell proliferation, a chemotherapeutic, an anti-viral drug, a gene therapy viral vector, or a combination thereof.
37. The formulation of any one of claims 28-36, wherein the pharmaceutical agent comprises bevacizumab.
38. The formulation of any one of claims 28-37, wherein the formulation is an ocular formulation.
39. An extended-release hydrogel comprising: a. a nucleo-functional polymer that is a biocompatible polymer containing a plurality of thio-functional groups -R1-SH wherein R1 is an ester-containing linker; b. an electro-functional polymer that is a biocompatible polymer containing at least one thiol-reactive group; and c. a pharmaceutical agent.
40. The extended-release hydrogel of any of claim 39, wherein the nucleo-functional polymer comprises a biocompatible poly(vinyl alcohol) polymer substituted by a plurality of thio-functional groups -R1-SH.
41. The extended-release hydrogel of any one of claims 39-40, wherein the electro- functional polymer is a biocompatible polymer comprising poly(ethylene glycol)polymer substituted by at least one thiol-reactive group.
42. The extended-release hydrogel of any one of claims 39-41, wherein the thiol-reactive group is an alpha-beta unsaturated ester, maleimidyl, sulfone, or combinations thereof.
43. The extended-release hydrogel of any one of claims 39-42, wherein the electro- functional polymer comprises a multi-arm polymer.
44. The extended-release hydrogel of any one of claims 39-43, further comprising an alkali metal salt.
45. The extended-release hydrogel of any one of claims 39-44, wherein the extended- release hydrogel has a crosslink time of less than about 10 minutes, less than about 7 minutes, less than about 5 minutes, less than about 3 minutes, less than about 1 minute, less than about 20 seconds, less than about 10 seconds, less than about 5 seconds, or less than about 1 second after mixing the nucleo-functional polymer and the electro-functional polymer when measured at 37°C.
46. The extended-release hydrogel of any one of claims 39-45, wherein the extended- release hydrogel has a degradation time that is greater than or equal to about 3, about 5, about 8, about 10, about 13, about 14, about 15, about 19, or about 32 days at 60°C.
47. The extended-release hydrogel of any one of claims 39-46, wherein the extended- release hydrogel releases the pharmaceutical agent over a period of at least about 5, about 10, about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, about 100, or about 120 days.
48. The extended-release hydrogel of any one of claims 39-47, wherein the pharmaceutical agent comprises an anti-inflammatory agent, a steroid, an NSAID, an intraocular pressure lowering drug, an antibiotic, a pain reliever, an inhibitor of vascular endothelial growth factor (VEGF), an inhibitor of abnormal vascular growth or vascular leakage, an inhibitor of abnormal cell proliferation, a chemotherapeutic, an anti-viral drug, a gene therapy viral vector, or a combination thereof.
49. The extended-release hydrogel of any one of claims 39-48, wherein the pharmaceutical agent comprises bevacizumab.
50. The extended-release hydrogel of any one of claims 39-49, wherein the extended- release hydrogel is for use in the eye of a subject.
51. A method for administering a pharmaceutical agent to a subject in need thereof, the method comprising: a. administering to the subject an effective amount of a nucleo-functional polymer, an electro-functional polymer, a pharmaceutical agent, and a pharmaceutically acceptable carrier; and b. allowing the nucleo-functional polymer and the electro-functional polymer to react to form an extended-release hydrogel in the subject; wherein the nucleo-functional polymer is a biocompatible polymer containing a plurality of thio-functional groups -R1-SH wherein R1 is an ester-containing linker, and the electro- functional polymer is a biocompatible polymer containing at least one thiol- reactive group.
52. The method of claim 51, wherein the nucleo-functional polymer, the electro- functional polymer, the pharmaceutical agent, and the pharmaceutically acceptable carrier are administered to the subject together in a single formulation.
53. The method of claim 51, wherein the nucleo-functional polymer and the electro- functional polymer are administered to the subject in separate formulations and following administration to the subject, the nucleo-functional polymer and the electro-functional polymer mix and react to form the extended-release hydrogel in the subject.
54. The method of claim 53, wherein the formulation comprising the nucleo-functional polymer comprises the pharmaceutical agent.
55. The method of claim 53 or 54, wherein the formulation comprising the electro- functional polymer comprises the pharmaceutical agent.
56. The method of any one of claims 51-55, wherein the nucleo-functional polymer comprises a biocompatible poly(vinyl alcohol) polymer substituted by a plurality of thio-functional groups -R1-SH.
57. The method of any one of claims 51-56, wherein the electro-functional polymer is a biocompatible polymer comprising poly(ethylene glycol)polymer substituted by at least one thiol-reactive group.
58. The method of any one of claims 51-57, wherein the thiol-reactive group is an alpha- beta unsaturated ester, maleimidyl, sulfone, or combinations thereof.
59. The method of any one of claims 51-58, wherein the electro-functional polymer comprises a multi-arm polymer.
60. The method of any one of claims 52-59, where the formulation further comprises an alkali metal salt.
61. The method of any one of claims 52-60, wherein the formulation has an osmolality in the range of about 200 mOsm / kg to about 400 mOsm / kg.
62. The method of any one of claims 52-61, wherein the formulation has an endotoxin level of less than about 20 endotoxin units/ml, less than about 15 endotoxin units/ml, less than about 10 endotoxin units/ml, less than about 5 endotoxin units/ml, less than about 2.5 endotoxin units/ml, less than about 1.0 endotoxin units/ml, less than about 0.8 endotoxin units/ml, less than about 0.5 endotoxin units/ml, less than about 0.2 endotoxin units/ml, or less than about 0.1 endotoxin units/ml.
63. The method of any one of claims 52-62, wherein the formulation has less than about 50 particles per mL with a size of ≥ 10 μm.
64. The method of any one of claims 52-63, wherein the extended-release hydrogel has a crosslink time of less than about 10 minutes, less than about 7 minutes, less than about 5 minutes, less than about 3 minutes, less than about 1 minute, less than about 20 seconds, less than about 10 seconds, less than about 5 seconds, or less than about 1 second when measured at 37°C.
65. The method of any one of claims 51-64, wherein the extended-release hydrogel has a degradation time that is greater than or equal to about 3, about 5, about 8, about 10, about 13, about 14, about 15, about 19, or about 32 days at 60°C.
66. The method of any one of claims 51-65, wherein the extended-release hydrogel releases the pharmaceutical agent over a period of at least about 5, about 10, about 20, about 30, about 40, about 50, about 60, about 70, about 80, about 90, about 100, or about 120 days.
67. The method of any one of claims 51-66, wherein the formulation has a viscosity of less than about 4000 cP, about 2000 cP, about 1000 cP, about 800 cP, about 600 cP, about 500 cP, about 400 cP, about 200 cP, about 100 cP, about 80 cP, about 60 cP, about 50 cP, about 40 cP, about 20 cP, about 10 cP, about 8 cP, about 6 cP, about 5 cP, about 4 cP, about 3 cP, about 2 cP about 1 cP prior to formation of the hydrogel.
68. The method of any one of claims 51-67, wherein the pharmaceutical agent comprises an anti-inflammatory agent, a steroid, an NSAID, an intraocular pressure lowering drug, an antibiotic, a pain reliever, an inhibitor of vascular endothelial growth factor (VEGF), an inhibitor of abnormal vascular growth or vascular leakage, an inhibitor of abnormal cell proliferation, a chemotherapeutic, an anti-viral drug, a gene therapy viral vector, or a combination thereof.
69. The method of any one of claims 51-68, wherein the pharmaceutical agent comprises bevacizumab.
70. The method of any one of claims 52-69, wherein the formulation is an ocular formulation.
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