WO2025065065A1 - Nanofibrous dermal mat, transdermal patches, dressings and dermatological products including same - Google Patents

Abstract

A nanofibrous dermal mat comprising: electrospun nanofibers formed from an electrospinning mixture of polyvinyl alcohol (PVA) and at least one polyglycol; and at least one active pharmaceutical ingredient (API) dispersed throughout said electrospun nanofibers.

Description

NANOFIBROUS DERMAL MAT, TRANSDERMAL PATCHES, DRESSINGS AND DERMATOLOGICAL PRODUCTS INCLUDING SAME FIELD OF INVENTION The present invention relates to a nanofibrous mat and products, such as transdermal patches, dressings and dermatological products that include such a nanofibrous mat. More particularly, the invention relates to a nanofibrous mat that is readily dissolvable in water or body fluid such as sweat, and products that include such mats. BACKGROUND ART As noted above, the invention broadly relates to nanofibrous mats. A particularly important application of the nanofibrous mat is transdermal patches. The following discussion of the background to the invention will specifically consider this field of application. However, this should be construed as limiting on the present invention solely to application in transdermal patches. For example, it is considered the nanofibrous mat may be equally applicable to use in dressings, such as wound or burn dressings, and dermatological products, such as face masks. Transdermal

Compared to standard routes of drug administration such as intravenous, intra muscular and oral, for some specific drugs the topical/transdermal route represents a more effective and patient centric alternative, leading to better patient compliance and adherence. Transdermal patches offer both precise and sustained dosage (controlled release). They allow continuous delivery of a therapeutic, with the potential to extend treatment for several days. As an example, potent drugs such as Fentanyl are administered routinely using transdermal patches, e.g., Duragesic®. Topical lidocaine patches, e.g., Lidoderm® or Versatis®, are commonly used for treatment of Post Shingles chronic pain (Herpetic Neuralgia). Lidocaine\Prilocaine EMLA® patches are routinely used for Instant skin numbing prior to carrying out small medical procedures. Despite their great advantages, there are crucial safety and economic concerns with the current transdermal patch systems. One of the foremost critical issue is “waste”. Typically, 50-95% of the drug incorporated in a patch is still unused at disposal and needs to be discarded. This has a strong economic impact, especially for expensive drugs like Cannabinoids or Fentanyl or Hormones. Importantly, unsafe disposal of unused patches can pose a serious public health issue, e.g., the opioid crisis faced by the American health system. The waste needs to be disposed of in a safe manner by the users. Inappropriate waste disposal, especially with regulated drugs such as Fentanyl and Lidocaine is a significant problem, often leading to accidental overdose or poisoning, drug abuse and environmental toxicity. In Australia and Europe, medicines (including patches) cannot be disposed of as general waste. They must not be poured down a sink, flushed down a toilet, or sent to landfill as they persist for a long time in the environment and in water supplies. The Environmental Protection Regulation requires that all medicine waste must undergo high temperature incineration. Additionally, for some treatments, the duration of application is limited by the irritation or skin reaction caused by the Active Pharmaceutical Ingredient (API) coming in direct contact of the skin. For example, post shingles Lidocaine pain patches need to be changed every 12 hours with a break of 12 hours between application to avoid this issue. This limitation can lead to suboptimal pain relief and patient distress during the gaps. It would be advantageous if a transdermal patch could be developed that addresses these issues by minimizing drug wastage and improving safety by drastically simplifying the disposal of any waste product of the transdermal patch after use. On developing the present invention, with particular consideration to application in the field of transdermal patches, the inventors have found that a dissolvable nanofibrous mat layer of the developed patch may have broader application. This is reflected in the scope of the present invention in the following description and claims. The subject matter claimed herein is not limited to embodiments that solve any disadvantages or that operate only in environments such as those described above. Rather, this background is only provided to illustrate exemplary technology areas where some embodiments described herein may be practiced. Various aspects and embodiments of the invention will now be described. SUMMARY OF INVENTION As mentioned above, the present invention relates generally to a nanofibrous mat and products, such as transdermal patches, dressings and dermatological products that include such a nanofibrous mat. More particularly, the invention relates to a nanofibrous mat that is readily dissolvable in water or body fluid such as sweat, and products that include such mats. According to one aspect of the invention there is provided a nanofibrous dermal mat comprising: electrospun nanofibers formed from an electrospinning mixture of polyvinyl alcohol (PVA) and at least one polyglycol; and at least one active pharmaceutical ingredient (API) dispersed throughout the electrospun nanofibers. Preferably the at least one polyglycol is selected from polyethylene glycol (PEG) and polypropylene glycol (PPG). In certain embodiments, the PVA is present in the electrospinning mixture in an amount of from 5-15 wt.%, preferably from 5-10 wt.%. The at least one polyglycol may be present in the electrospinning mixture in an amount of from 0.5 wt.% to 10 wt.%. For example, the at least one polyglycol may comprise PEG in an amount of from 0.5 to 5 wt.%. The at least one polyglycol may also comprise PPG in an amount of from 0.5 wt.% to 10 wt.%. The electrospinning mixture preferably further comprises a solvent. The solvent is preferably selected from ethanol, methanol, propylene glycol, dimethyl sulfoxide DMSO, dimethylformamide (DMF), isopropyl alcohol, 1-butanol/n- butanol. The electrospinning mixture may further comprise a surfactant. The surfactant may be selected from TWEEN surfactants, Brij surfactants and Span surfactants. For example, the surfactant may be TWEEN 20, TWEEN 40, TWEEN 60, TWEEN 80. According to certain embodiments, the nanofibrous dermal mat has a Mat GSM (g/m²) of from 10-100 g/m². The nanofibrous dermal mat may have an API GSM (g/m²) of from 2-40 g/m². It is envisaged that higher Mat GSM and API GSM will be achievable, for example it is envisaged that a Mat GSM of up to 200 g/m² and an API GSM of up to 100 g/m² may be attainable. Generally, the electrospun nanofibers of the nanofibrous dermal mat have a diameter of from 200-800 nm, preferably with the majority (>90%) ranging below 600nm. The API may be hydrophobic or hydrophilic. For example, the API may be selected from cannabinoids, such as cannabidiol (CBD), Delta-9- tetrahydrocannabinol (THC), Delta-8-tetrahydrocannabinol (Δ8-THC), Cannabichromene (CBC), Cannabicyclol (CBL), Cannabigerol (CBG), Cannabinodiol (CBND), Cannabinol (CBN), Cannabitriol (CBT), members of the Caine family, such as Lidocaine, Prilocaine, Bipuvacaine, Dibucaine, Opioids, such as Fentanyl, Codeine, Morphine, Buprenorphine, Psylocibin (hydrophilic). In a specific example, the solids in the electrospinning mixture comprises PVA in an amount of from about 30 wt.% to 60 wt.%, PEO in an amount of from about 4 wt.% to 11 wt.%, acetic acid in an amount of from about 2.5 wt.% to 5.5 wt.%, Tween 20 in an amount of up to 10 wt.% and CBD in an amount of from about 30 wt.% to 60 wt.%. Nanofibrous dermal mat produced may have a GSM ranging from about 10 to 85 g/m² and a CBD loading of from about 0.45 mg/cm² to 3.50 mg/cm². In another specific example, the solids in the electrospinning mixture comprises PVA in an amount of from about 30 wt.% to 40 wt.%, PEO in an amount of from about 0 wt.% to 9.5 wt.%, PPG in an amount of from about 25 wt.% to 35 wt.%, acetic acid in an amount of from about 2 wt.% to 5.5 wt.% and CBD in an amount of from about 24 wt.% to 30 wt.%. Nanofibrous dermal mat produced may have a GSM ranging from about 2.2 to 46 g/m² and a CBD loading of from about 0.1 mg/cm² - 1.6 mg/cm². In certain embodiments, the electrospinning mixture further comprises Hemp Seed Oil (HSO), for example in an amount of up to 10 wt.%. In certain embodiments, the electrospinning mixture further comprises Poly Vinyl Pyrrolidone (PVP), for example in an amount of up to 50 wt.%. In still further embodiments, the electrospinning mixture further comprises a Terpene (for example Menthol) and/or an Essential oil (for example Clove Oil) or mixture of Essential Oils, for example in an amount of up to 10 wt.%. According to another aspect of the invention there is provided a transdermal patch comprising: a nanofibrous dermal mat as described above; optionally an occlusive backing layer overlying the nanofibrous dermal mat to which the nanofibrous dermal mat is applied; and an adhesive layer overlying the nanofibrous dermal mat or occlusive backing layer. The occlusive backing layer may be formed from siliconised wax paper, electrostatically treated polyethylene (antistatic PE), polyethyleneterephthalate (antistatic PET) and nonwoven polypropylene. The patch can be applied with and without occlusion and can be applied to skin moisturised with water, lotions , hydrating gels or creams. The adhesive layer may comprise a breathable, elastic polymeric substrate, preferably a polyurethane substrate coated with a hypoallergenic and non- cytotoxic adhesive. According to a further aspect of the invention there is provided a dressing comprising a nanofibrous dermal mat as described above. According to yet another aspect of the invention there is provided a dermatological product comprising a nanofibrous dermal mat as described above. The dermatological product may be, for example, a face mask. According to a further aspect of the invention there is provided a method of producing a nanofibrous dermal mat comprising: providing an electrospinning mixture comprising polyvinyl alcohol (PVA), at least one polyglycol, a solvent and at least one active pharmaceutical ingredient (API); depositing the electrospinning mixture onto a substrate using an electrospinning device, thereby forming the nanofibrous dermal mat with the API dispersed throughout electrospun nanofibers formed from the polyvinyl alcohol (PVA) and the at least one polyglycol. As with the above description of the nanofibrous dermal mat, the at least one polyglycol is preferably selected from polyethylene glycol (PEG) and polypropylene glycol (PPG). The PVA may be present in said electrospinning mixture in an amount of from 5-15 wt.%, preferably from 5-10 wt.%. The at least one polyglycol may be present in the electrospinning mixture in an amount of from 0.5-10 wt.%. For example, the at least one polyglycol may comprise PEG in an amount of from 0.5-5 wt.%. The at least one polyglycol may comprise PPG in an amount of from 0.5-10 wt.%. As previously described, the electrospinning mixture further comprises a solvent. The solvent may be selected from ethanol, methanol, propylene glycol, dimethyl sulfoxide DMSO, dimethylformamide (DMF), isopropyl alcohol, 1- butanol/n-butanol. The electrospinning mixture may further comprises a surfactant. The surfactant may be selected from TWEEN surfactants, Brij surfactants and Span surfactants. The nanofibrous dermal mat produced may have a Mat GSM (g/m²) of from 10- 85 g/m². The API may be hydrophobic or hydrophilic. For example, the API may be selected from cannabinoids, such as cannabidiol (CBD), Delta-9- tetrahydrocannabinol (THC), Delta-8-tetrahydrocannabinol (Δ8-THC), Cannabichromene (CBC), Cannabicyclol (CBL), Cannabigerol (CBG), Cannabinodiol (CBND), Cannabinol (CBN), Cannabitriol (CBT), members of the Caine family, such as Lidocaine, Prilocaine, Bipuvacaine, Dibucaine, Opioids, such as Fentanyl, Codeine, Morphine, Buprenorphine, Psylocibin (hydrophilic). In a certain embodiment the solids in the electrospinning mixture comprise PVA in an amount of from about 30 wt.% to 60 wt.%, PEO in an amount of from about 4 wt.% to 11 wt.%, acetic acid in an amount of from about 2.5 wt.% to 5.5 wt.%, Tween 20 in an amount of up to 10 wt.% and CBD in an amount of from about 30 wt.% to 60 wt.%. According to this embodiment, the nanofibrous dermal mat may have a GSM ranging from about 10 to 85 g/m² and a CBD loading of from about 0.45 mg/cm² to 3.50 mg/cm². In another embodiment the solids in the electrospinning mixture comprise PVA in an amount of from about 30 wt.% to 40 wt.%, PEO in an amount of from about 0 wt.% to 9.5 wt.%, PPG in an amount of from about 25 wt.% to 35 wt.%, acetic acid in an amount of from about 2 wt.% to 5.5 wt.% and CBD in an amount of from about 24 wt.% to 30 wt.%. According to this embodiment, the nanofibrous dermal mat may have a GSM ranging from about 2.2 to 46 g/m² and a CBD loading of from about 0.1 mg/cm² - 1.6 mg/cm². In certain embodiments, the electrospinning mixture further comprises Hemp Seed Oil (HSO), for example in an amount of up to 10 wt.%. In certain embodiments, the electrospinning mixture further comprises Poly Vinyl Pyrrolidone (PVP), for example in an amount of up to 50 wt.%. In still further embodiments, the electrospinning mixture further comprises a Terpene (for example Menthol) and/or an Essential oil (for example Clove Oil) or mixture of Essential Oils, for example in an amount of up to 10 wt.%. According to another aspect of the invention there is provided use of a nanofibrous dermal mat, a patch or a dressing as described above for the treatment of pain, such as chronic pain, muscoskeletal pain, cancer pain, neuropathic pain and diabetic pain, burns, or for the treatment of anxiety, epilepsy, PTSD, inflammation and insomnia. BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS To further clarify various aspects of some embodiments of the present invention, a more particular description of the invention will be rendered by references to specific embodiments thereof, which are illustrated in the appended drawings. It should be appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting on its scope. The invention will be described and explained with additional specificity and detail through the accompanying drawings in which: FIG.1 illustrates a cross-sectional view of a transdermal patch according to an embodiment of the invention applied to the skin. FIG.2 illustrates a underside view of the patch of FIG.1. FIG. 3 illustrates an SEM of a nanofibrous electrospun polymeric fiber mat containing Cannabidiol. FIGS.4A and 4B illustrate the fibre morphologies as imaged by SEM for Mat 1A and Mat 1B respectively. FIG.5 illustrates an SEM image of a Tween containing Mat. FIG.6 illustrates an SEM image of a PPG containing Mat. FIG.7 illustrates an SEM image of a Lidocaine containing Mat. FIG. 8 is a graph illustrating transfer of mats from backing layers of various patches to the skin. FIG.9 illustrates a comparison between the XRD traces of pure CBD & Encapsulated CBD in the nanofibers. FIG. 10 illustrates a graph of CBD release from cast gel versus from nanofibrous mats. FIGS.11A to 11D illustrate the dissolution of different formulation mats over 1 hour, including Mat 1A, Mat 1B, Mat with Tween 20 and Matt with PPG respectively. FIG.12 illustrates a graph of CBD release from different formulation mats at 3 hours. FIG. 13 illustrates an image at 180 minutes showing the different levels of dissolution of various mats. FIGS.14A and 14B illustrate graphs of the comparison of Lidocaine permeation through A) artificial skin (Start-M membrane) and B) human skin of commercial (Versatis patch) and nanofibrous patch. FIGS.15A to 15D illustrate graphs showing the comparison of permeation from Mat 1A, Mat 1B, Mat Tween 20 and Mat PPG respectively (shown as solid black line) with four different commercial mats (CM1, CM2, CM3 and CM4) (shown as grey lines with different marker format). FIG.16 illustrates a graph showing the comparison between the Mat 1A, Mat 1B, Mat Tween 20 and Mat PPG mats (patterned bars) and commercial mats (solid bars) with regards to total %CBD released (in the receiving buffer and in the membrane) and the % remaining unused in the mat at 24 hours. FIG.17 illustrates Fibre morphology: SEM of the Electro-spun mats using PG, PPG 400, and PPG 2000) (x2000 magnification). FIG. 18 illustrates a graph showing amount of CBD released in 24 hours for mats containing PG, PPG-400, and PPG-2000 (10 wt. % in the mat) through the Strat-M membrane. The release studies were carried out using a Franz cell diffusion apparatus. FIG.19 illustrates a graph showing percentage of CBD released at 24 hr from the Mats synthesised with increasing HSO concentrations. CBD Released= CBD Permeated through the Membrane + CBD extracted from the STRAT-M membrane. FIG. 20 illustrates a graph showing Average Fibre Diameter as a function of increasing PVP concentration (50 measurement/sample) (n represents number of trials at different concentrations of PVP). FIG.21 illustrates Fibre morphology: SEM of the Electro-spun mats at different concentrations of PVP (x2000 magnification). FIG. 22 illustrates a graph showing Amount of CBD remaining and released after 24h from Nanofibrous Mat synthesised with various amount of PVP (PEO Mw = 300k and PVP Mw = 360k). Note: Total CBD release represents release into and across the Strat-M membrane. FIG.23 illustrates a graph showing Moisture uptake at 24h of mats containing different levels of PVP (n=3, n represents number of trials). FIG.24 illustrates a graph showing evolution of the viscosity of electrospinning polymeric mixes with different amount of PVP with time. FIG. 25 illustrates Fibre morphology: SEM of the Electro-spun mats using Menthol and Clove oil (x2000 magnification). FIG.26 illustrates graphs showing HPLC trace from pure Clove oil (top panel) and Clove oil leached from electrospun mats (lower panel). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, this specification will describe the present invention according to the preferred embodiments. It is to be understood that limiting the description to the preferred embodiments of the invention is merely to facilitate discussion of the present invention and it is envisioned without departing from the scope of the appended claims. Referring to Figures 1 and 2, a transdermal patch 10 is illustrated. The transdermal patch 10 is composed of at least three layers. Prior to application, a nanofibrous mat layer 11 which is dissolvable and contains a drug encapsulated inside polymeric nanofibers is generally covered by a removable protective layer (not shown). On removal of the protective layer the nanofibrous mat layer is applied to the skin 12. Polymers used for producing the nanofibers in the nanofibrous layer 11 are biodegradable and can dissolve rapidly in contact with water or body fluids such as sweat. A backing layer 13 is provided on which the nanofibrous mat layer 11 is deposited or transferred. The backing layer 13 is generally impervious to water and is occlusive once applied to the skin 12. Such occlusion leads to accumulation of sweat in the application area which triggers dissolution of the nanofibrous mat layer 11. The backing layer 13 is typically slightly larger than the nanofibrous mat layer 11 to provide that occlusion, as best illustrated in Figure 2. It is noted that the backing layer 13 is optional and may be excluded such that the nanofibrous mat layer 11 is directly contacted with an adhesive layer 14. The adhesive layer 14 constitutes an outer layer of the transdermal patch 10 in use. The adhesive layer 14 facilitates adhesion of the transdermal patch 10 to the skin 12. The adhesive layer 14 is usually significantly larger than the backing layer 13, if present, and the nanofibrous mat layer 11 to ensure good adhesion to the skin 12. Fabrication of the dissolvable patch The nanofibrous mat is a polymeric matrix made by preparing an electrospinnable solution containing: • a mixture of polyvinyl alcohol (PVA) and at least one polyglycol, for example Poly Ethylene Glycol (PEG), also known as Poly Ethylene Oxide (PEO) or poly(oxyethylene) (POE), or Poly Propylene Glycol (PPG), typically mixed as an aqueous solution; • The Active Pharmaceutical Ingredient (API); • A solvent for the API which is also compatible with the chosen polymer mixture; and • Optionally a surfactant which may help solubilize the active and/or, reduce the surface tension of the mixture and/or might act as a penetration enhancer. This solution is mixed mechanically and, if required, ultrasonicated or mixed with a rotor stator to achieve a homogenous solution or fine suspension, where the drug does not fully dissolve. The polymeric solution is then deposited onto a substrate using an electrospinning device. In electrospinning, as a general principle, fibers are generated by applying high potential between a syringe needle or a thin wire coated with polymeric solution and a receiving substrate or collector. The fibers are deposited in a non-woven fashion in a mat format on the substrate while it is moving. The resulting layer forms a non-woven mat, constituting the nanofibrous mat layer 11, made of intermingled polymeric fibers. Figure 3 provides an SEM image of a nanofibrous electrospun polymeric fiber mat containing Cannabidiol. The substrate can function as the final backing layer 13 that will be incorporated in the final patch 10 or alternatively, as a transient substrate. In the latter scenario, the nanofibrous layer should not adhere strongly to the substrate so the polymeric mat can be easily peeled off from the substrate and transferred to the final impervious backing layer 13 of the patch 10. During fiber formation, the API is encapsulated inside the polymer fibers and is homogeneously distributed in its amorphous form. Once produced, the nanofibrous mat layer 11 deposited on the impervious backing layer 13 is punched to the desired size and shape (see Figure 3). The patch 10 is assembled by transferring the nanofibrous mat layer 11 and backing layer 13 to a polyurethane membrane coated with an adhesive which forms the adhesive layer 14. The backing layer 13 is bonded to the adhesive layer 14 by contact. The resulting patch 10 is protected by using an adhesive protector and an over tape protector which enables the patch 10 to be easily handled and avoid contamination or damages to the active nanofibrous mat layer 11. Each individual patch is then wrapped to protect it from moisture during shipping and storage. Release of the drug from the dissolvable patch To use the patch 10, the protecting layers (not shown) are removed and the patch 10 is then pressed onto the skin 12, bringing the nanofibrous mat layer 11 in direct contact with the skin 12, which may be wetted prior to application. As moisture and skin oils are generated through sweating, the occlusion due to the impervious backing layer 13 prevents evaporation. This moisture accumulation leads to dissolution of the polymeric nanofibrous mat layer 11. It is considered that the dissolution of the polymeric nanofibrous mat layer 11 is due to the high surface area created by the multitudes of nanofibers in an open non-woven structure created during electrospinning. When similar formulations are used as cast layers, the cast films dissolve much slower which translates into a slower drug release (see Figure 10). Once the biodegradable polymer forming the nanofibrous mat layer 11 dissolves, it forms a very thin gelatinous deposit spread on the surface of the skin 12, which then liberates the API that can then permeate into and through the skin 12. At the end of the application period (12-72h), the patch 10 is removed by peeling the adhesive layer 14 and backing layer 13 off the skin 12. Since all of the API has been released onto the skin 12, the remaining patch does not contain any residual API (see Figure 9) and can be safely disposed of through the normal household waste stream (i.e., bin). Characteristic of the dissolvable patch The components of a patch will be discussed in more detail below, including examples of suitable options for each component. 1. Electrospun nanofibrous mat Typically, the nanofibrous mats is comprised of nanofibers having diameters ranging from 100 nm to 900 nm, with the majority (>90%) having diameters below 600nm. The nanofibers are formed from a polymer mixture that includes Poly Vinyl Alcohol (PVA) and at least one polyglycol, such as Poly Ethelyne Oxide or Poly Ethylene Glycol (PEO or PEG) or Poly Propylene Glycol (PPG). Other water soluble polymers may also be included in the polymer mixture, such as Poly Vinyl Pyrrolidone (PVP), poly acrylic acids (PAA) and natural polymers such as Xantham Gum, Guar Gum, Pectins, Alginates, Dextran, Carrageenan, Hyaluronic Acid, Chitosan, Cellulose and Cellulose derivatives (plant and animal derived), Starch and Starch derivatives. The nanofibrous mat contains an encapsulated drug or API. Both, hydrophobic or hydrophilic API’s can be encapsulated in the nanofibrous mat. Though typically, hydrophobic API’s are easier to permeate through the skin. A solvent (aqueous and/or organic) might be required in order to facilitate the dissolution of the API into the polymer mixture. Because the polymer solution is typically an aqueous solution, the solvent should preferably be miscible in water. A surfactant can also be used to increase the solubility of the API into the polymer mix and/or to reduce the surface tension of the polymeric mix. BP/FDA approved surfactant for topical applications include TWEEN 20, Tween 40, Tween 60, and TWEEN 80. Other surfactants may also be useful, such as Brij and Span surfactants. 2. Water resistant, impervious backing layer A water resistant, impervious backing layer is used to prevent diffusion of the API back into the backing layer, both, during fabrication or storage. If the backing layer is used as a deposition substrate during electrospinning then it needs to be slightly conductive. Typical materials are siliconised wax paper, electrostatically treated Polyethylene (antistatic PE) or Polyethylene Terephthalate (antistatic PET). Nonwoven Polypropylene substrates may also be appropriate. 3. Adhesive layer An adhesive layer is provided to facilitate adhesion of the patch to the skin. The adhesive layer is made of a breathable and elastic polymeric substrate such as Medical grade Poly Urethane coated with an Hypoallergenic and non-cytotoxic adhesive. EXAMPLES Example of Dissolvable patches Materials and Methods The chemicals used in the preparation of the nanofibrous mats were sourced according to the table below. The following materials were used to synthesise the Nanofibrous Mats: Materials Source/details CBD >99.6% purity, Pharma Hemp d.o.o. (Slovenia) Lidocaine Yick-Vic Chemicals and Pharmaceuticals EtOH HPLC grade, MERCK P_VA Polyvinyl alcohol 18-88, EMPROVE ^ Mw ^130000 (MERCK) PEO Polyethylene oxide, average Mw 400000 (Sigma Aldrich) PPG Polypropylene glycol P 400, Sigma Aldrich Acetic Acid Rowe Scientific Tween 20 15 % w/w, Polysorbate 20, EMPROVE ^MERCK Distilled Water Table 1: Materials for electrospinning PVA-PEO Mats (Mat 1A and Mat 1B) Synthesis In this example, details of synthesis of two nanofibrous mats (Mat 1A and Mat 1B) with different proportions of the water soluble polymers and the API are shown. The electrospinning mixture using the polymers and CBD was produced to the required specifications and then electrospun using Needle free electrospinning using Nanospider™ NS LAB (Elmarco s.r.o; Czech Republic) to produce CBD containing nanofibrous polymeric mats. The following materials were used to synthesise the Nanofibrous Mats 1A and 1B: Materials Mat 1A (wt%) Mat 1B (wt%) CBD 11.48 8.10 EtOH 21.74 16.21 PVA 6.96 7.95 PEO 1.24 1.30 Acetic Acid 0.66 0.78 Water 58.58 66.74 Table 2: Composition of the Electrospinning mixture The electrospinning solution was produced by mixing the required amounts of different materials as follows: CBD was dissolved in Ethanol and once mixed well, required amount of 16% PVA solution (in DI water) was added. After the solution was mixed well (handheld spatula, ultrasonication or rotor stator), to this 10% PEO (in DI water) was added and mixed well using a handheld spatula or ultrasonication. Finally, 1 M acetic acid and the remaining amount of water were added to this mix with continuous stirring. Once a homogeneous solution (white in appearance) was obtained, the viscosity of the solutions was measured (912.0 cP for Mat 1A and 1316.7cP for Mat 1B), prior to its use for electrospinning. The nanofibrous mats were produced from 100 mL of the electrospinning solution yielding mats of 38 cm x 100 cm for Mat 1A and 36cm x 105 cm for Mat 1B and these were then characterised as follows. Characterisation Homogeneity was characterised in terms of weight of solid deposited per unit of surface area (GSM) and loading which is defined by the weight of CBD per unit of surface area (GSM). The weight of solid was measured by accurately weighing several (n≥20) cored samples (1.54 cm²) sampled from various areas of the mat (see Table 3). The CBD loading was measured using high performance liquid chromatography (HPLC). A known weight of the mat is extracted in Ethanol/0.1%TFA in water mixed in 50:50 ratio by continuous shaking overnight, the supernatant was collected after centrifugation at 15,000g and filtered using 0.22 micron filters prior to HPLC (LC1260 Infinity II system (Agilent). An isocratic method was used, using the mobile phase (Acetonitrile (75%) and 0.1%TFA in DI water (25%) and either the Synergi 4 um Hydro-RP (Phenomenex) or Zorbax BONUS - RP Agilent 5 um, 4.6 x 250 mm column (Agilent). The CBD was detected at 220 nm and the peak was noted at 15.8 minutes, which was then analysed to estimate the CBD content (grams/square meter) (see Table 3). The fibre morphology was studied using scanning electron microscope(SEM) (JEOL JCM 5000 Neoscope). The fibre diameter (nm) was measured by SEM, averaging the measurement of least 50 fibres across the samples (see Table 3). Mat GSM (g/m²) CBD GSM (g/m²) Fibre diameter (nm) Mat 1A 41.21±2.5 16.8±0.6 384±23.3 Mat 1B 33.41±1.9 15.8±0.8 275±9.5 Table 3: Characterisation of Mat 1A and Mat 1B Figures 4A and 4B illustrate the fibre morphologies as imaged by SEM for Mat 1A and Mat 1B respectively. Mat with addition of the surfactant This is an example of synthesis and characterisation of a nanofibrous mat with addition of Tween 20. The main rationale for this was to explore the impact on the electrospinning efficiency via reducing the surface tension of the electrospinning mix. It was also expected to improve solubilisation of hydrophobic CBD in the water based polymer mix, and finally it is anticipated that Tween 20 in the mat will enhance the permeation of CBD across the skin when applied. The electrospinning solution was produced by mixing the required amounts (as per Table 4) of different materials as described below. The only difference was that Tween 20 was mixed into CBD/Ethanol mix prior to addition of the polymers. Once a homogeneous solution (white in appearance) was obtained, the viscosity of the solution was measured (2167.6cP) before its use for electrospinning. Materials wt% CBD 7.20 Ethanol 14.37 Tween 20 2.84 PVA 8.04 PEO 1.39 Acetic Acid 0.69 Water 83 Table 4: Composition of the Electrospinning mixture for Mat with Tween 20 Using a 100 mL electrospinning mix, a mat of 35 cm x 203 cm was produced. This was characterised as described above for homogeneity of Mat GSM, CBD GSM, fibre morphology. The GSM of the mat and CBD loading (GSM) was determined from mat samples collected from different parts of mat (Table 5, n>20). The fibre morphology was also determined using SEM (Figure 6) and acquired images were analysed for fibre diameter (n=50). Mat GSM (g/m²) CBD GSM (g/m²) Fibre diameter (nm) 22.78 ± 0.54 2.68±0.44 358±24 Table 5: Characterisation of Mat with Tween 20 Figure 5 illustrates an SEM image of Tween containing Mat. Synthesis of Mat with PPG This is an example of synthesis and characterisation of a nanofibrous mat with addition of Polypropylene Glycol (PPG). It is a polymer of Propylene Glycol (PG) and is the most hydrophilic form of the polymer. PG may be used to solubilise hydrophobic drugs. The possibility of solubilising CBD in PPG was explored, followed by exploring the potential for producing mats with a final composition. In preliminary studies, it was found that it PPG can help with solubilizing CBD. When CBD dissolved in ethanol was mixed with PPG 400, >94% of the CBD was transferred from Ethanol phase to PPG phase. This occurred because, relative to Ethanol, PPG 400 is more hydrophobic. PPG 400 was also found to be very compatible with the water-based polymer system of the invention. Polymer mats with addition of PPG were produced and characterised. A nanofibrous PPG mat containing CBD was produced using the following materials (see Table 6). Materials wt% CBD 5.76 PPG 5.76 PVA 7.23 PEO 1.53 Acetic Acid 1.11 Water 78.62 Table 6: Composition of the Electrospinning mixture for Mat with PPG The solubilisation of CBD in PPG 400 was performed using a phase separation technique.3g of CBD was dissolved in 3 g of Ethanol (HPLC grade, MERCK). A 50% PPG 400 solution was prepared and mixed vigorously with CBD/Ethanol solution, forming a yellowish milky emulsion. A phase separation was observed after 10 Minutes. Once the phase separation was complete and a clear interface was noted, the top phase containing ethanol and water were removed and CBD in PPG phase was estimated. This solution was subsequently used to produce the electrospinning mix. The electrospinning solution was produced by adding required amounts of 16% PVA (Table 6) to the CBD/PPG mix followed by 10% PEO and then 1M acetic acid with thorough mixing between each step. Once a homogeneous solution was obtained, the viscosity of the solution was measured (1979 cP), and it was used for electrospinning. The GSM of the mat and CBD loading (GSM) was determined from mat samples collected from different parts of mat (Table 7). The fibre morphology was also determined using SEM (Figure 6) and acquired images were analysed for fibre diameter (n=50). Mat GSM (g/m²) CBD GSM (g/m²) Fibre diameter (nm) 29.58 ± 1.4 8.17±0.47 333±25 Table 7: Characterisation of Mat with PPG Synthesis of Lidocaine patch Lidocaine is a small molecule hydrophobic drug, but it is relatively less hydrophobic than Cannabinoids. Lidocaine patches are used for post herpetic neuralgia following Shingles pain. These provide topical relief from the chronic nerve pain that persists in >30-40% of the patients post shingles. Lidocaine patches containing Lidocaine base encapsulated in the polymeric mats were produced using the following composition (Table 8). Materials wt% Lidocaine base 6.49 PVA 9.77 PEO 0.56 Tween 20 1.46 Ethanol 24.41 Water 57.31 Table 8: Composition of the Electrospinning mixture for Lidocaine Mats The electrospinning mix was produced by hand mixing the lidocaine powder in Ethanol, followed by addition of Tween 20. Once thoroughly mixed, 16% PVA was added to the required concentration and mixed followed by mixing with required amounts of 10% PEO. Finally, the remainder of water was added to produce an electrospinning mix of viscosity 600cPa, which was then electrospun. Characterisation of the lidocaine mat was performed for GSM via weighing 1.54 cm² circular samples, obtained from different parts of the mat. The Lidocaine loading was determined by HPLC of the extracted Lidocaine using 0.1% TFA(70%) /Acetonitrile (30%) solution using the “Phenomenex Fusion column (4.6 µ)” column. The lidocaine peak was observed at ~4.5 minutes. The data was analysed to determine the loading of the mats (Table 9). SEM imaging (Figure 7) was carried out as described in sections above. Mat GSM (g/m²) Lidocaine GSM Fibre diameter (nm) (g/m²) Mat 1 41.07±2.8 14.8±0.9 529±28.5 Table 9: Characterisation of Lidocaine Mat Transfer of the Drug containing ES mats to the skin In this experiment, the four types of CBD mats (Mat 1A, Mat 1B, Mat Tween and Mat PPG) were applied to the skin, swabbed with distilled water. After 5 minutes, the mats were peeled off using fine forceps, the backing layer was collected and extracted with 80:20 mixture of Ethanol and phosphate buffer at pH5.6. The transferred mat was also peeled off for analysis in a similar manner. Triplicates were done for all samples. The data clearly showed that the backing layer contained from 0.02-0.1% of the CBD applied, with most of the CBD being transferred to the skin (Figure 8). Obtention of the necessary drug payload Introduction For good efficacy, transdermal patches need to contain a sufficient dose of the drug per square surface area to deliver therapeutic quantities of the drug efficiently into the system. Typically, for post neuropathic neuralgia, Versatis/Lidoderm patches contain 700mg of lidocaine per patch of 140cm2; EMLA patches contain 25 mg lidocaine and 25 mg of prilocaine in a 40cm2 patch and between CBD patches contain between 20-100mg for CBD in 25 cm2 patches. Using standard electrospinning conditions and using a pure PVA formulation it is only possible to achieve mats with less than 20 GSM (grams per square meter) thickness. In general, the GSM of the mat is expected to correlate with the drug loaded. Even with an exceptionally high drug loading of 50% of drug per dry patch weight, a maximum of 10g of drug per square meter or 1 mg/cm² would be achieved. This means that for a typical PVA only patch of 20 GSM, one would fall significantly short of the required dose. Similarly, for a typical 25cm² patch only 140mg of lidocaine can be loaded instead of 700 mg and a maximum of 25mg of CBD can be loaded. It was anticipated that high GSM should also lead to high drug loading. In order to achieve higher GSM, the addition of other polymers to the mix that could potentially improve the spinnability of the polymeric mix and hence improve the rate of deposition as well as absolute deposition/square surface area (i.e. GSM) was explored. Specifically, water soluble polymers were chosen for compatibility with the water based system and also to avoid any adverse impact on the hydrophilicity of the final mat. Formulation enabling high GSM and high drug loading A series of electrospinning experiments were conducted to explore the impact of changing the composition of the electrospinning mix (Polymers, additives such as surfactants) and process parameter (such as voltage) on the final GSM and CBD loading of the electrospun mat. In general, it was found that higher voltage yielded high GSM mats. A very strong positive correlation was observed between the total GSM of the mat and the CBD loading; the Pearson correlation coefficient of 0.87759533 was noted (r²= 0.7702, N=91) and the relationship was significant (p <0.0001). Of all the parameters tested a clear positive correlation of percentage of PEO was noted with the mat GSM and hence CBD GSM (Correlation coefficient: 0.81282755, N=31, r2: 0.6607, p<0.0001). PEO ranging from 0% to 11.1% in the electrospinning mix, yielded, mats at GSM ranging from 2.23 to 80.61. Overall, a composition comprising of PVA (from 32.6% to 59.2%), PEO (4%- 11.1%), Acetic acid (between 2.5 to 5.2%), Tween 20 (up to 10%) and CBD (33.5-57.1%) yielded mats at GSM ranging from 10.23 to 80.61. The corresponding CBD loading ranged from 0.488 mg/cm² to 3.78mg/cm². Addition of polypropylene glycol (PPG) was also tested, firstly because of its hydrophilicity its compatibility with the water-based electrospinning mix. The concept was to enhance solubilization of the CBD in the electrospinning mix and then to also explore the possibility of enhancing the permeation of the hydrophobic drugs through the skin, given the well-established permeation enhancement properties of monomeric Propylene Glycol. The mats electrospun with addition of polypropylene glycol polymer, were produced using a composition comprising of PVA between 31.1% to 39%, PEO between (0-9.5%), PPG (26.2-35.1%), acetic acid (2.3% to 5.2%) and CBD between 24.3% to 30%, yielding a GSM of 2.23 to 46 obtaining CBD loading at 0.1-1.6 mg/cm². Enhanced permeation Some hydrophobic drugs like CBD do not penetrate skin well. Surprisingly, the encapsulation of API inside our nanofibrous mats produced using electrospinning increased the penetration of the drug through skin. It is considered that this can be due to 3 factors: • Encapsulation of the drug in Nanofibrous structure leads to amorphization of the drug which is known to enhance solubility and thus bioavailability (Kim, D.; Kim, Y.; Tin, Y.-Y.; Soe, M.-T.-P.; Ko, B.; Park, S.; Lee, J. Recent Technologies for Amorphization of Poorly Water-Soluble Drugs. Pharmaceutics 2021, 13, 1318). • The use of PVA as a polymer to produce nanofibres enhances the penetration of drug through the skin. • The use of other hydrophilic polymers (PEO and PPG) or additives such as Tween, also enhance penetration. Amorphization of the Active through encapsulation and Electrospinning As evidenced by the comparison between the XRD spectra of the CBD isolate and Mat 1A (see Figure 8), the CBD contained in the nanofibrous mat is not fully crystalline but contain a significant amount of amorphous CBD. Figure 9 illustrates a comparison between the XRD traces of pure CBD & Encapsulated CBD in the nanofibers. Dissolution and release behavior of casted vs nanofibrous mat The following experiments were conducted to demonstrate that encapsulation in a polymeric nanofiber facilitates earlier and faster drug release. For this, the electrospinning mixture prepared to produce Mat 1B (Table 1) was also cast in the form of a gel on a Teflon surface to obtain evenly distributed gel at about 50 GSM. The same electrospinning mix was used to produce nanofibrous mats (Table 2). The cast gel with CBD was dried at room temperature over the weekend and then 6mm cores were cut using a coring device and weighed. Similarly, 6mm cores were obtained from the nanofibrous CBD mats. A fixed amount of PBS buffer was added and sampling was done at 10 minutes, 30 minutes, 60 minutes, 180 minutes and 240 minutes. The samples were diluted 1:1 with ethanol and the CBD content was determined by HPLC. The data clearly shows early and faster release from the nanofibrous mats verses the cast mats, where the CBD is slowly released after 60 minutes with gradual increase onwards (Figure 10). Whilst from the nanofibrous mats, most of the CBD is released by 180 minutes. The faster release of CBD from nanofibers is likely due to the high surface area of the nanofibers allowing greater exposure of the drug to external solvent causing faster release. CBD release from mats prepared using different formulations In these experiments, the four different formulation mats were dissolved in 1 ml of Phosphate buffer and the supernatant was sampled at 2, 5, 10, 30, 60 or 180 minutes. After dilution in Ethanol at 1:1, the supernatants were analysed for CBD quantity by HPLC. The data clearly shows a difference in the way the 4 mats dissolved, with Mat 1A and PPG mat demonstrating the fastest dissolution (see Figure 11 for visual data over 60 minutes). Mat with Tween 20 was the slowest to dissolve followed by Mat 1B, with Mat 1A and PPG mats showing the fastest dissolution. Figures 11A to 11D illustrate the dissolution of different formulation mats over 1 hour, including Mat 1A, Mat 1B, Mat with Tween 20 and Matt with PPG respectively. In each panel, from left vial to right vial, photographic images at 2, 5, 10, 30 and 60 minutes for each mat type are shown. The first vial being at 2 minutes, followed by 5 minutes, 10 minutes, 30 minutes and 60 minutes. Cloudy supernatant is indicative of dissolution The CBD released from each mat in general followed their dissolution behaviour (Figure 12). The data clearly shows that changing the formulation modifies the release rates from different mats. It is possible to achieve early and fast release as well as slower release using different formulations. The fast- dissolving Mat 1A and Mat with PPG, released CBD as early as 5 minutes, with most released (~70%-85%) by 30 minutes. In the other hand, slow dissolving Mat 1B displayed earliest release at 10 minutes with gradual and sustained release at 15% from 30 minutes onwards. The slowest dissolving Mat with Tween 20, however, released very small percentage of its payload by 3 hours (~1%). Figure 12 illustrates a graph of CBD release from different formulation mats at 3 hours. The graph shows release of %CBD released based on the total amount present in the mat. Figure 13 is an image at 180 minutes showing the different levels of dissolution of various mats. Influence of PVA on the permeation As demonstrated in the graph of Figure 14 comparing penetration through the Human skin of a commercial lidocaine patch and a dissolvable lidocaine patch, the % dose permeated from the lidocaine dissolvable patch is significantly higher than the commercial patch. Similarly, when the four different types of CBD dissolvable mats (Mat 1A, Mat 1B, Mat Tween 20, Mat PPG) were tested against a series of commercial counterparts (CM1, CM2, CM3 and CM4), for permeation through artificial skin (Strat M membrane), the permeation was either superior or similar to that noted for the commercial patches (Figure 15). While there are no medicinal CBD patches presently on the market, a range of wellness patches with varying levels of CBD were selected. It is interesting to note that CBD is present either as a part of the extract or isolate and mixed with a plethora of permeation enhancers to achieve penetration through the skin. While the current mechanism which is providing enhanced transport across the skin from dissolved PVA is not understood, it is clear that the encapsulation of API inside a PVA based nanofiber system does significantly enhance transport across the skin. Addition of PEO improved the electrospinning outcomes without changing the permeation behavior significantly from of the PVA CBD mats. However, when PEO levels were increased as with Mat 1B, the dissolution of the mat was slower (see Figures 12 and 13) and permeation across the membrane was not significantly different, releasing between 52-55% of CBD across and in the artificial skin at 24h (see top panel of Figures 15A to 15D). The same mat however, when electrospun with addition of the surfactant Tween 20 to facilitate electrospinning by reducing the surface tension of the electrospinning mix, displayed significantly superior performance (~64% released) compared to all the commercial mats tested (Figure 15C). Similarly, when PPG was added to the polymer mix, again surprisingly, the permeation was far superior (73% released) to any of the commercial mats (Figure 15 D). Accordingly, the amount of CBD remaining unused in the mats was the lowest for the PPG Mat and the Mat with Tween 20, followed by the Mats 1A and 1B (Figure 16). All data is averaged from 3-6 Franz cell diffusion experiments using Synthetic Start-M membrane for permeation. Use of Propylene glycol and polypropylene glycols for Electrospun mat production Poly Propylene Glycol (PPG) shares a similar structure with PEG but includes an extra methylene group in its monomer unit. This structural variation makes PPG significantly more hydrophobic compared to PEG, giving it distinct properties related to amphiphilic nature and micelle formation. The addition of PPG has been found to have a significant impact on the release of CBD from the PVA/PEO mats (figure 15D). The following discussion evaluates whether the molecular weight of PPG impacts on the process of electrospinning and the subsequent properties of the mats, such as CBD incorporation or CBD release. In the following example, Propylene glycol (PG) and its polymers, PPG 400 and PPG 2000, were assessed for their electro-spinnability and impact on permeation. Mats containing 10 wt.% of the polyglycols were produced. Composition of the Electrospinning mix The composition of the electrospinning mixes to produce Glycol containing mats is shown in Table 10. CBD PVA PEO Acetic acid Ethanol Type of Glycol or Polyglycol Wt.% in the electrospinning mix PG 7.66 48.7 7.60 13.72 20.34 10 wt.% * PPG-400 6.4 57.68 8.10 10.63 15.50 10 wt.% * PPG-2000 6 60 7.75 9.64 15.31 10 wt.% * Table 10: Composition of the Glycol and Polyglycol electrospinning mix *The weight % here represents the % wt./wt. in the final electro spun mat. Characterisation of the PG and PPG containing mats: Characterisation was carried out as described in sections above. CBD loading was determined by HPLC, Fibre morphology and fibre diameter (n=50/sample) by SEM (Figure 17), and homogeneity of the mats in terms of their weight (g) /square-meter and CBD loading (g/square meter) was also assessed (n=6) (Table 11). Mat Sample GSM CBD GSM Fibre Moisture (g/m²) (g/m²) diameter content ± SEM ± SEM nm (%) ± SEM ± SEM PG 38.44± 12.26 ± 0.94 390±115 5.04 ± 0.18 1.91 PPG-400 47.48± 12.91 ± 1.06 555±239 7.11 ± 4.29 3.93 PPG-2000 40.87± 9.26 ± 0.47 581±283 4.1 ± 0.29 2.25 Table 11. Characterisation of the ES mats containing 10 wt.% of PG, PPG-400, and PPG-2000. The fibre diameter increases with increasing molecular weight. Additionally, the fibres in PG containing mats appeared to retain greater moisture inside these fibres when compared to mats with no polyglycols (measured at 2.35 +/- 0.37%). When tested for permeation across the Strat-M membrane, the release trends correlated with molecular weight of PPG. Polymeric glycols performed better than PG. Figure 18 illustrates a graph of amount of CBD released in 24 hours for mats containing PG, PPG-400, and PPG-2000 (10 wt. % in the mat) through the Strat-M membrane. The release studies were carried out using a Franz cell diffusion apparatus. Addition of Hemp Seed Oil to produce polymeric mats As part of formulation development, the impact of Hemp seed oil (HSO) addition on several properties was explored. Overall, the goal was to develop a long- term patch (72h) with moisturising and healing ability. The specific goal was to: 1) enhance loading and homogeneity of loading in the mats; 2) improve permeation of the CBD through the skin; and 3) demonstrate the potential to encapsulate essential oils using the technology. Hemp Seed Oil (HSO) is “Generally Recognized as Safe” (GRAS) by the U.S. Food & Drug Administration. HSO is noteworthy because of its content of flavonoids, terpenes, carotenoids and phytosterols which engenders anti- inflammatory and anti-aging properties. Its primary constituents are omega 3 and omega 6 fatty acids, along with some anti-inflammatory terpenes and amino acids, mineral (magnesium, calcium and iron) and vitamins (e.g. Vitamin E), all of which can be absorbed through the skin. It naturally contains tocopherol and chlorophyll. It is a rapidly absorbed and non-comedogenic oil. This oil is used for formulations to treat skin issues and stress as well as treat inflammation for all skin types, especially sensitive skin, and as a sun cream and for anti-ageing formulations. Given its composition and its origin (Hemp, Cannabis sativa), it is postulated that it may enhance CBD’s efficacy and bioavailability topically and trans-dermally via an entourage effect. Several polymeric mats containing the polymer combination of PVA/PEO and 1%, 2.5%, and 5% HSO were produced (n=5-16, n represents number of experiments) (Table 12) and characterised (Table 13). Electrospinning of HSO containing mats The following example details the production and characterisation of HSO containing mats. The composition of the electrospinning mix for production of various mats is listed in Table 12. Components Mat: HSO Mat: HSO Mat: HSO Mat: (wt.%) 0%* 1%* 2.5%* HSO 5%* CBD 5-10 6-8 3-8 6-9 PVA 29-56 44-52 23-54 44-55 PEO 5-21 10-18 7-32 11-15 HSO 0 0.2-0.3 1 1 Tween 20 0-3 3 2-4 0-3 Ethanol 14-20 13-16 12-16 13-19 Water 0-14 0 0-14 0 Acetic acid 4-14 12-13 8-13 7-13 Table 12: Electrospinning mix for production of HSO containing nanofibrous mats * The percentage of HSO in the top row displays wt. % in the final mat produced from the corresponding electrospinning mix (composition in the lower rows). Characterisation of the HSO containing mats Characterisation of Hemp seed oil mats was done as described in sections above: CBD loading was determined by HPLC, Fibre morphology and diameter by SEM, and homogeneity of the mats in terms of their weight(g) /square meter and of CBD loading was assessed (n=6) (Table 13). Sample GSM Mat CBD GSM Fibre Diameter (g/m²) (g/m²) (nm) ± SEM ± SEM ± SEM 0 % HSO 36.39 ± 1.11 16.97 ± 0.58 0.452 ± 0.053 1 % HSO 27.69 ± 0.62 9.66 ± 0.12 0.786 ± 0.205 2.5 % HSO 27.63 ± 0.58 8.82 ± 0.28 0.603 ± 0.064 5 % HSO 30.49 ± 0.75 11.06 ± 0.54 0.771 ± 0.107 Table 13: Characterisation of Hemp seed oil containing samples (n=5-16 n=number of trials performed at different concentrations of HSO). Addition of HSO leads to increased homogeneity of the polymeric mats: A surprising outcome was the positive correlation (0.474, n = 42) between the amount of HSO (%) and homogeneity of GSM. This suggested that the mats produced with HSO are likely to have a higher level of homogeneity. This correlated with increasing concentration of HSO, as shown by the decreasing % error value after addition of HSO. Addition of HSO has a strong positive correlation with fibre diameter The fibre diameter increased with addition of HSO (0.6279, n=42), from 400 nm in mats with no HSO to ~700 nm in mats with HSO . It was anticipated that smaller fibre diameter will correlate positively with higher rate of dissolution and possibly with higher permeation of CBD due to increase in surface area. Impact of addition of HSO on the release of CBD from the mats A comparison of permeation across the Strat-M membrane by Franz cell are summarized in Table 14 and Figure 19. The mats without HSO showed a relatively high CBD release (Total release combines the CBD measured in the Strat-M membrane and permeated across in the receiving buffer depicting permeation). When HSO is added at 1%, the release decreases, though, at higher % HSO, a gradual increase was observed with increasing amount of HSO. The decrease in release of CBD with the introduction of HSO can be explained by a slower dissolution of the mat caused by the larger fibre diameter. The gradual increase with the increasing amount of HSO introduced in the system suggests that increasing quantities of HSO potentially negates the impact of high fibre diameter and improves the % of CBD released. This could be attributed to HSO hydrophobicity which could help solubilise the CBD and promote its permeation into and through the Strat M membrane. This affinity of HSO for CBD is likely to also enhance penetration through hydrophobic barriers, i.e. the stratum corneum (SC) of the skin generating a greater reservoir of CBD in SC. This reservoir effect could lead to increased permeation across the lower layers of the skin. HSO wt. % GSM: GSM: CBD CBD Total CBD (in the Mat) Mat (g/m²) (g/m²) Permeated released (%) ± ± SEM ± SEM (mg) ± SEM SEM ** 0 36.71 ± 17.01 ± 0.56 0.39 ± 0.027 64.97 ± 3.74 1.08 1 26.23 ± 10.08 ± 0.38 0.17± 0.033 46.51 ± 6.08 0.70 2.5 27.63 ± 8.82 ± 0.28 0.29 ± 0.034 60.63 ± 3.33 0.58 5 30.49 ± 11.06 ± 0.54 0.35 ± 0.041 66.75 ± 3.94 0.75 Table 14. Release characteristics of polymeric mats synthesised with varying HSO Concentrations. * CBD Permeated = CBD measured in the receiving buffer across the STRAT- M membrane **Total CBD Released: CBD Permeated + CBD extracted from the STRAT-M membrane Polymeric electro-spun mats with addition of Poly Vinyl Pyrrolidone (PVP) For effective application of polymeric encapsulation mats, continuous release of the active over 72h is highly desirable. For this, drying of the polymeric film should be avoided and retaining moisture in the dissolved polymeric depot at the surface of the skin is important. Therefore, incorporation of a hygroscopic polymer in the formulation of the nanofibrous mat could be beneficial. Towards that goal, another hydrophilic polymer, Poly Vinyl Pyrrolidine (PVP), was assessed for production of electrospun mats. Poly Vinyl polymers e.g. PVP, PVA and Poly Vinyl Acetate (PVAc) are extensively used for the development of controlled-release products. PVP was selected because: • it is hydrophilic and hence is compatible with the present system; • it is known to enhance the solubility and bioavailability of poorly water- soluble drugs. PVP-based polymers have been shown to play a crucial role in the formation of Amorphous Solid Dispersions (ASD) through maintaining the amorphous state of the drug and inhibiting drug recrystallization. This is a common problem faced by the current drug patches and could be particularly beneficial in patches especially during storage. • it may stabilise the polymeric formulation: For large scale production of the mats described herein, long-term stability of the electrospinning solutions is important. One of the issues is that while PVA is highly hydrophilic and biocompatible, it forms unstable solutions, and its molecules can re-entangle under physiological conditions. Blending with PVP may decrease this through linkage by H- bond potentially raising stability of the mix under physiological conditions. • it is possible that addition of PVP may improve the wettability and swelling properties of the blend. In summary, PVP was assessed to improve the hygroscopicity of the mats and stability of the electrospinning mix, and to explore potential impact on the CBD loading and release. Electrospinning of PVP containing Mats HSO content of 2.5 wt. % was selected for our base formulation for this body of work. Electrospun CBD mats were produced using PVP (molecular weight of 360k), PVA and PEO (MW300k-600k). Table 15 provides details of composition range used for PVP containing mats. Components (wt.%) PVA-PEO-PVP CBD 3 – 8 Hemp Seed Oil 0 – 1 Tween 20 2 – 3 PVA 17 – 45 PEO* 9 – 27 PVP 7 – 47 Acetic acid 7 – 13 Ethanol 9 – 17 Water 0 - 13 Table 15: Composition of electrospinning mix used for PVP containing mats *Concentrations was modified to accommodate the viscosity changes due to PEO molecular weight. Characterisation of PVP containing mats The mats were characterised for CBD loading, Fibre morphology, Diameter and Homogeneity of loading and GSM as described in examples above. Sample* GSM CBD GSM Fibre diameter (g/m²) (g/m²) nm ± SEM ± SEM ± SEM 0% PVP 30.09 ± 1.18 11.85 ± 0.30 0.521± 0.038 5% PVP 45.00 ± 2.99 14.25 ± 0.70 0.299 ± 0.012 15% PVP 42.09 ± 2.44 12.35 ± 0.53 0.386 ± 0.025 20% PVP 33.42 ± 2.59 11.40 ± 0.94 0.290 ± 0.009 25% PVP 38.92 ± 3.14 10.00 ± 0.58 0.382 ± 0.023 30% PVP 30.21 ± 1.89 5.75 ± 0.33 0.354 ± 0.017 Table 16 – Characterisation of PVP mats. *The mats were produced using 300k PEO. Impact of the addition of PVP on the fibre diameter The fibre diameters of PVA/PEO/PVP mats (300-400 nm) are smaller than that for PVA/PEO mats (~600 nm) (Figure 20). This was noted despite the presence of HSO, suggesting that PVP helps counteract the increase in the fibre diameter due to HSO. However, while the fibre diameter did not change significantly at different concentration of PVP, the beading in the fibres was significantly reduced with increasing concentration of PVP. This indicates the stabilising impact and improved electro-spinnability of the ES mix with increasing PVP concentration (Figure 21). Impact of addition of PVP on the release of CBD The impact of PVP addition on the release of CBD from the mats was evaluated by Franz cell diffusion system using Strat-M membrane (see Table 17 and Figure 22). The data clearly showed that addition of PVP enhanced significantly the release of CBD from the mats at 24 hr, up to 70%. However, at various concentration of PVP, very similar release profiles were noted with no clear trends (Table 17). CBD CBD in CBD Total release remaining the Strat- CBD Permeat (%Membran PVP in the M GSM ± ed e % used membra SEM % ± +%Permeate patch ne SEM d) ± SEM * % ± SEM % ± SEM 11.85 ± 59.08 ± 24.6 16.33 0 40.93 ±1.59 0.30 0.49 ±1.34 ±1.83 14.25 ± 40.47 ± 41.32 ± 18.19 5 59.51 ± 4.14 0.70 1.8 5.04 ±3.24 12.35 ± 45.17 ± 36.36 ± 18.48 15 54.84 ± 3.82 0.53 2.59 5.11 ±2.52 11.40 ± 48.17 ± 27.84 ± 23.98 20 51.82 ±0.42 0.94 0.81 0.81 ±0.04 10.00 ± 44.86 ± 43.27 11.87 25 55.14 ±6.12 0.58 8.32 ±10.27 ±1.96 5.75 32.97 53.80 13.22 30 67.02 ± 3.76 ± 0.33 ±7.52 ±7.07 ±0.45 Table 17: Comparison of PVP content and CBD release through Franz cell at

Impact of addition of PVP on the hygroscopicity of the mats The impact of PVP addition on hygroscopicity of the resulting mats was assessed by measuring the moisture uptake by different mats over 24h at high humidity (RH: 75%). Specifically, electrospun mats without PVP and with different concentrations of PVP were cut into 1.54-cm² discs and their masses were measured with an analytical balance (n=3). The discs were placed in Eppendorf tubes with lids open, and incubated at 75% relative humidity (RH) and 25 °C. After 24 hours in the incubator, the samples were weighed again. The moisture content of the electro-spun fibres was calculated using the following formula: ^^ ^^ ^^ ^^ℎ ^^ ^^ ^^ ^^ ^^ ^^ − ^^ ^^ ^^ ^^ℎ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ ^^ (%) = × 100 ^^ ^^ ^^ ^^ℎ ^^ ^^ ^^ ^^ ^^ ^^ ^^ The data clearly showed an increase in moisture uptake with increasing PVP% in the mat, demonstrating the increased hygroscopic nature of the mat with PVP amount (Figure 23). Impact of the addition of PVP over the stability of the electrospinning mix The impact of PVP addition on the stability of the electrospinning mix was assessed by measuring the change in viscosity (cP) over 24 h (n=3). Viscosity of the polymeric solution is a key parameter for electrospinning. This dictates the spinnability of the solution and the ability to produce nanofibrous mats. Variation in solution viscosity can lead to changes to the specifications of the mats such as fibre diameter, GSM and active loading. During production, a variation of viscosity can lead inhomogeneity in the mat specifications (e.g. GSM and the active loading). The viscosity of electrospinning solutions without PVP and with different concentrations of PVP was measured over a period of 24 hours using a rotational viscometer, Visco-895 with an A3 spindle at 100 rpm. The temperature varied between 22°C and 23°C. During the first 8 hours, viscosity was measured every hour. Changes in viscosity over the 24h period are minimised by addition of PVP (Figure 24). This demonstrates an enhanced stability of the electrospinning mix with addition of PVP over 24 h. This stability of the ES mix is crucial to ensuring homogeneous mats during scaled up production over extended periods. Addition of Terpenes and Essential Oils In the following example, we describe ES mats produced with addition of Terpene (Menthol) and Essential oil (Clove Oil). In addition to potentially contributing to entourage effect to improve CBD absorption, it was expected that terpenes and/or essential oils may also further enhance CBD permeation by disrupting the skin's outer layer, increasing its lipid solubility, and improve absorption. Specific examples of incorporation of Menthol (Terpene) and Clove oil (Essential oil) are described below. Composition For these mats, the base composition selected was PVA/PEO/PVP/HSO. The composition range for these mats is described in Table 18. Components wt.% CBD 3 – 8 Hemp Seed Oil <1 Menthol/Clove oil <1 Tween 20 2 – 3 PVA 17 – 45 PEO* 9 – 27 PVP 7 – 47 Acetic acid 7 – 13 Ethanol 9 – 17 Water 0 - 13 Table 18: Composition of electrospinning mix used for Menthol or Clove oil containing mats Characterisation The mats were characterised for CBD loading (n=6), Fibre morphology, Diameter (n=50) and Homogeneity of loading and GSM (n=6) as described in examples above. Addition of Menthol or Clove oil led to production of mats with very similar fibre morphologies and diameters at 606 nm and 667nm, respectively (Figure 25 and Table 19). Addition of both led to an increase in fibre diameter from about 300- 400nm in the base composition (Figure 20, 20%PVP) up to ~600 nm (Table 19). The GSM of the mats was found to be very similar (~40g/m²) for both, though higher than the base formulation (~33 g/m², Table 16). And CBD loading appeared to be higher for mats with Clove oil addition (Table 19), which was comparable to that obtained in the base composition. The process of electrospinning had no impact on the integrity of clove oil (Figure 26), as shown by very similar HPLC trace of the clove oil in the mat and the that of the pure standard (1 mg/mL). The amount of clove oil present within a mat sample was measured by HPLC isocratic run using a mobile phase of 60/40 Acetonitrile/DI water (0.1% TFA). The mat samples were leached in the mobile phase, and the oil layer separated for analysis. HPLC peaks seen with pure Clove oil and Clove oil leached from an electrospun mat showed matching peaks at 6.2 and 7.45 minutes, with no visible degradation of the oil because of the electrospinning process. Further quantification of the clove oil incorporation in the mats showed ~5% loading in the mat with minimal loss during the process (<25%) (Table 20), suggesting the feasibility of this approach. Terpene or Essential Oil GSM CBD GSM Fibre diameter (g/m²) (g/m²) nm ± SEM ± SEM ± SEM N=6 N=6 N=50 Menthol 40.91 ± 3.46 8.01 ± 0.36 0.606 ± 0.029 Beta-Caryophyllene 42.77 ± 1.20 12.27 ± 0.62 0.667 ± 0.053 (Clove oil) Table 19 – Characterisation of PVA-PEO-PVP mats with Menthol or Clove oil. Loading of Expected Calculated Clove oil in Clove oil in Clove oil in mat (%) sample (mg) sample (mg) 4.94 31.70 23.87 Table 20 - Calculated amount (by HPLC) of Clove oil in the electrospun mat sample. Throughout this specification, unless the context requires otherwise, the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated step or element or integer or group of steps or elements or integers, but not the exclusion of any other step or element or integer or group of steps, elements or integers. Thus, in the context of this specification, the term “comprising” is used in an inclusive sense and thus should be understood as meaning “including principally, but not necessarily solely”. Unless the context requires otherwise or specifically stated to the contrary, integers, steps or elements of the invention recited herein as singular integers, steps or elements clearly encompass both singular and plural forms of the recited integers, steps or elements. It will be appreciated that the foregoing description has been given by way of illustrative example of the invention and that all such modifications and variations thereto as would be apparent to persons of skill in the art are deemed to fall within the broad scope and ambit of the invention as herein set forth.

Claims

CLAIMS 1. A nanofibrous dermal mat comprising: electrospun nanofibers formed from an electrospinning mixture of polyvinyl alcohol (PVA) and at least one polyglycol; and at least one active pharmaceutical ingredient (API) dispersed throughout said electrospun nanofibers.

2. A nanofibrous dermal mat according to claim 1, wherein said at least one polyglycol is selected from polyethylene glycol (PEG) and polypropylene glycol (PPG).

3. A nanofibrous dermal mat according to any one of the preceding claims, wherein said PVA is present in said electrospinning mixture in an amount of from 5-15 wt.%, preferably from 5-10 wt.%.

4. A nanofibrous dermal mat according to any one of the preceding claims, wherein said at least one polyglycol is present in said electrospinning mixture in an amount of from 0.5-10 wt.%. 5. A nanofibrous dermal mat according to claim 4, wherein said at least one polyglycol comprises PEG in an amount of from 0.

5-5 wt.%.

6. A nanofibrous dermal mat according claim 4 or 5, wherein said at least one polyglycol comprises PPG in an amount of from 0.5-10 wt.%.

7. A nanofibrous dermal mat according to any one of the preceding claims, wherein said electrospinning mixture further comprises a solvent.

8. A nanofibrous dermal mat according to claim 7, wherein said solvent is selected from ethanol, methanol, propylene glycol, dimethyl sulfoxide DMSO, dimethylformamide (DMF), isopropyl alcohol, 1-butanol/n- butanol.

9. A nanofibrous dermal mat according to any one of the preceding claims, wherein said electrospinning mixture further comprises a surfactant.

10. A nanofibrous dermal mat according to claim 9, wherein said surfactant is selected from TWEEN surfactants, Brij surfactants and Span surfactants.

11. A nanofibrous dermal mat according to any one of the preceding claims, wherein said nanofibrous dermal mat has a Mat GSM (g/m²) of from 10- 100 g/m².

12. A nanofibrous dermal mat according to any one of the preceding claims, wherein said nanofibrous dermal mat has an API GSM (g/m²) of from 2- 40 g/m².

13. A nanofibrous dermal mat according to any one of the preceding claims, wherein said electrospun nanofibers have a diameter of from 200-800 nm, preferably with the majority (>90%) ranging below 600nm.

14. A nanofibrous dermal mat according to any one of the preceding claims, wherein said API hydrophobic or hydrophilic.

15. A nanofibrous dermal mat according to claim 14, wherein said API is selected from cannabinoids, such as cannabidiol (CBD), Delta-9- tetrahydrocannabinol (THC), Delta-8-tetrahydrocannabinol (Δ8-THC), Cannabichromene (CBC), Cannabicyclol (CBL), Cannabigerol (CBG), Cannabinodiol (CBND), Cannabinol (CBN), Cannabitriol (CBT), members of the Caine family, such as Lidocaine, Prilocaine, Bipuvacaine, Dibucaine, Opioids, such as Fentanyl, Codeine, Morphine, Buprenorphine, Psylocibin (hydrophilic).

16. A nanofibrous dermal mat according to claim 1, wherein solids in said electrospinning mixture comprise PVA in an amount of from about 30 wt.% to 60 wt.%, PEO in an amount of from about 4 wt.% to 11 wt.%, acetic acid in an amount of from about 2.5 wt.% to 5.5 wt.%, Tween 20 in an amount of up to 10 wt.% and CBD in an amount of from about 30 wt.% to 60 wt.%.

17. A nanofibrous dermal mat according to claim 16, wherein said nanofibrous dermal mat has a GSM ranging from about 10 to 85 g/m² and a CBD loading of from about 0.45 mg/cm² to 3.50 mg/cm².

18. A nanofibrous dermal mat according to claim 1, wherein solids in said electrospinning mixture comprise PVA in an amount of from about 30 wt.% to 40 wt.%, PEO in an amount of from about 0 wt.% to 9.5 wt.%, PPG in an amount of from about 25 wt.% to 35 wt.%, acetic acid in an amount of from about 2 wt.% to 5.5 wt.% and CBD in an amount of from about 24 wt.% to 30 wt.%.

19. A nanofibrous dermal mat according to claim 18, wherein said nanofibrous dermal mat has a GSM ranging from about 2.2 to 46 g/m² and a CBD loading of from about 0.1 mg/cm² - 1.6 mg/cm².

20. A nanofibrous dermal mat according to any one of the preceding claims, wherein the electrospinning mixture further comprises Hemp Seed Oil (HSO), for example in an amount of up to 10 wt.%.

21. A nanofibrous dermal mat according to any one of the preceding claims, wherein the electrospinning mixture further comprises Poly Vinyl Pyrrolidone (PVP), for example in an amount of up to 50 wt.%.

22. A nanofibrous dermal mat according to any one of the preceding claims, wherein the electrospinning mixture further comprises a Terpene (for example Menthol) and/or an Essential oil (for example Clove Oil) or mixture of Essential Oils, for example in an amount of up to 10 wt.%.

23. A transdermal patch comprising: a nanofibrous dermal mat according to any one of the preceding claims; optionally an occlusive backing layer overlying said nanofibrous dermal mat to which the nanofibrous dermal mat is applied; and an adhesive layer overlying said nanofibrous dermal mat or occlusive backing layer.

24. A transdermal patch according to claim 23, wherein said occlusive backing layer is formed from siliconised wax paper, electrostatically treated polyethylene (antistatic PE), polyethyleneterephthalate (antistatic PET) and nonwoven polypropylene.

25. A transdermal patch according to claim 23 or 24, wherein said adhesive layer comprises a breathable, elastic polymeric substrate, preferably a polyurethane substrate coated with a hypoallergenic and non-cytotoxic adhesive.

26. A dressing comprising a nanofibrous dermal mat according to any one of claims 1 to 22.

27. A dermatological product comprising a nanofibrous dermal mat according to any one of claims 1 to 22.

28. A dermatological product according to claim 27, wherein said dermatological product is a face mask.

29. A method of producing a nanofibrous dermal mat comprising: providing an electrospinning mixture comprising polyvinyl alcohol (PVA), at least one polyglycol, a solvent and at least one active pharmaceutical ingredient (API); depositing the electrospinning mixture onto a substrate using an electrospinning device, thereby forming said nanofibrous dermal mat with said API dispersed throughout electrospun nanofibers formed from said polyvinyl alcohol (PVA) and said at least one polyglycol.

30. A method according to claim 29, wherein said at least one polyglycol is selected from polyethylene glycol (PEG) and polypropylene glycol (PPG).

31. A method according to claim 29 or 30, wherein said PVA is present in said electrospinning mixture in an amount of from 5-15 wt.%, preferably from 5-10 wt.%.

32. A method according to any one of claims 29 to 31, wherein said at least one polyglycol is present in said electrospinning mixture in an amount of from 0.5-10 wt.%.

33. A method according to claim 32, wherein said at least one polyglycol comprises PEG in an amount of from 0.5-5 wt.%.

34. A method according to claim 32, wherein said at least one polyglycol comprises PPG in an amount of from 0.5-10 wt.%.

35. A method according to any one of claims 29 to 34, wherein said electrospinning mixture further comprises a solvent.

36. A method according to claim 35, wherein said solvent is selected from ethanol, methanol, propylene glycol, dimethyl sulfoxide DMSO, dimethylformamide (DMF), isopropyl alcohol, 1-butanol/n-butanol.

37. A method according to any one of claims 29 to 36, wherein said electrospinning mixture further comprises a surfactant.

38. A method according to claim 37, wherein said surfactant is selected from TWEEN surfactants, Brij surfactants and Span surfactants.

39. A method according to any one of claims 29 to 38, wherein said nanofibrous dermal mat has a Mat GSM (g/m²) of from 10-85 g/m².

40. A method according to any one of claims 29 to 39, wherein said API is hydrophobic or hydrophilic.

41. A method according to claim 40, wherein said API is selected from cannabinoids, such as cannabidiol (CBD), Delta-9-tetrahydrocannabinol (THC), Delta-8-tetrahydrocannabinol (Δ8-THC), Cannabichromene (CBC), Cannabicyclol (CBL), Cannabigerol (CBG), Cannabinodiol (CBND), Cannabinol (CBN), Cannabitriol (CBT), members of the Caine family, such as Lidocaine, Prilocaine, Bipuvacaine, Dibucaine, Opioids, such as Fentanyl, Codeine, Morphine, Buprenorphine, Psylocibin (hydrophilic).

42. A method according to claim 29, wherein solids in said electrospinning mixture comprise PVA in an amount of from about 30 wt.% to 60 wt.%, PEO in an amount of from about 4 wt.% to 11 wt.%, acetic acid in an amount of from about 2.5 wt.% to 5.5 wt.%, Tween 20 in an amount of up to 10 wt.% and CBD in an amount of from about 30 wt.% to 60 wt.%.

43. A method according to claim 42, wherein said nanofibrous dermal mat has a GSM ranging from about 10 to 85 g/m² and a CBD loading of from about 0.45 mg/cm² to 3.50 mg/cm².

44. A method according to claim 29, wherein solids in said electrospinning mixture comprise PVA in an amount of from about 30 wt.% to 40 wt.%, PEO in an amount of from about 0 wt.% to 9.5 wt.%, PPG in an amount of from about 25 wt.% to 35 wt.%, acetic acid in an amount of from about 2 wt.% to 5.5 wt.% and CBD in an amount of from about 24 wt.% to 30 wt.%.

45. A method according to claim 44, wherein said nanofibrous dermal mat has a GSM ranging from about 2.2 to 46 g/m² and a CBD loading of from about 0.1 mg/cm² - 1.6 mg/cm².

46. A method according to any one of claims 29 to 45, wherein the electrospinning mixture further comprises Hemp Seed Oil (HSO), for example in an amount of up to 10 wt.%.

47. A method according to any one of claims 29 to 46, wherein the electrospinning mixture further comprises Poly Vinyl Pyrrolidone (PVP), for example in an amount of up to 50 wt.%.

48. A method according to any one of claims 29 to 47, wherein the electrospinning mixture further comprises a Terpene (for example Menthol) and/or an Essential Oil (for example Clove Oil) or mixture of Essential Oils, for example in an amount of up to 10 wt.%.

49. Use of a nanofibrous dermal mat according to any one of claims 1-22, a patch according to any one of claims 23-25 or a dressing according to claim 26 for the treatment of pain, such as chronic pain, muscoskeletal pain, cancer pain, neuropathic pain and diabetic pain, or for the treatment of anxiety, epilepsy, PTSD, inflammation and insomnia.