WO2013034173A1

WO2013034173A1 - Pramipexole extended release tablets

Info

Publication number: WO2013034173A1
Application number: PCT/EP2011/065343
Authority: WO
Inventors: Korinde Annemarie JANSSEN
Original assignee: Synthon BV
Current assignee: Synthon BV
Priority date: 2011-09-06
Filing date: 2011-09-06
Publication date: 2013-03-14
Anticipated expiration: 2014-03-06
Also published as: WO2013034550A1

Abstract

A tablet composition for a controlled and pH-independent release of the pharmaceutically active compound pramipexole from the tablet matrix after oral administration has been provided. The composition comprises a water-soluble, preferably dihydrochloride, salt of pramipexole, at least one non-ionic, not gelling release-controlling polymer and at least one non-ionic, gelling release-controlling polymer.

Description

PRAMIPEXOLE EXTENDED RELEASE TABLETS

BACKGROUND OF THE INVENTION

The present invention relates to an extended-release tablet for delivering pramipexole, making and using such a tablet.

Pramipexole of the formula (I)

is a pharmaceutically active compound acting as a dopamine D2 receptor agonist. It is indicated for treating early stage Parkinson's disease and restless legs syndrome (RLS), furthermore it is investigated for treating bipolar disorder, clinical depression and fibromyalgia.

Pramipexole is the (S)-enantiomer of N⁶-propyl-4,5,6,7-tetrahydro-l,3-benzothiazole-2,6- diamine. The (R)-enantiomer thereof, the dexpramipexole, is investigated for treatment of amyotropic lateral sclerosis (ALS).

In the marketed medicaments, which are tablets for oral administration, pramipexole is present in the form of a dihydrochloride monohydrate salt. This salt is a crystalline compound, which is extremely well soluble in water.

Originally, pramipexole has been sold (under brand names Mirapexin® or Sifrol®) as tablets with immediate release of the drug; the inactive ingredients are mannitol, maize starch, colloidal silica, povidone and magnesium stearate. The usual therapeutical dose is one tablet comprising from 0.125 to 1.5 mg of pramipexole dihydrochloride monohydrate three times a day. Subsequently, an extended release tablet has been developed and introduced into clinical practice (e.g. under the brand name Mirapex^® ER or Sifrol^® ER); such tablet comprising from 0.375 to 4.5 mg of pramipexole dihydrochloride is administered once-a-day.

Due to the extreme solubility of pramipexole dihydrochloride monohydrate in an aqueous environment (about 200 mg/ml at 25°C), formulating a tablet with an extended release of pramipexole is considered difficult in the prior art teaching.

One option is to make a tablet comprising a release-controlling coating.

Thus, WO 03/053402 discloses a zero-order controlled release tablet suitable for administration of water-soluble therapeutically active compounds, said tablet comprising a matrix core comprising ethylcellulose and a hydrophobic polymer coating encasing the entire matrix core.

WO 2004/010982 discloses a compressed tablet with an active agent dispersed therein, wherein the tablet is coated with at least two coating layers comprising a water-insoluble coating polymer and a water-soluble pore former.

WO 2004/010997 and WO 2004/010999 disclose an extended release tablet composition comprising a water-soluble salt of pramipexole, which is dispersed in a matrix comprising a hydrophilic polymer, preferably HPMC, and a starch having a tensile strength of at least 0.15 kN.cm^"2. The starch of this grade is characterized as a "super binder" and is able to provide good mechanical hardness to the tablet. Although the hydrophilic polymer provides sustained-release, the tablet is preferably coated with a release-controlling coating comprising a hydrophobic polymer. In a second option, the extended release tablets contain specific excipients efficiently modulating the release of pramipexole from the tablet matrix. Based on the known data, it appears that the marketed Sifrol^® ER tablets have been constructed this way. The release- controlling agents thereof are hydroxypropyl methylcellulose (HPMC) and carbomer (a polyacrylic acid); further, the tablet contains maize starch (as a filler/binder, which has a synergistic effect with HPMC to delay release), anhydrous colloidal silica and magnesium stearate.

Thus, the currently marketed ER pramipexole tablets are monolithic tablets (both pramipexole and excipients are uniformly dispersed in the matrix) that are based on a hydrophilic polymer matrix comprising two water swelling polymers - a neutral polymer (HPMC) and an anionic polymer (carbomer). Such tablets have been disclosed in WO 2006/015942. Similar compositions have been disclosed in WO 2006/015944 and in WO 2007/090881.

Carbomers are pH-sensitive release-controlling agents. They are effective in particular at a pH of 4.5 and higher. At a lower pH, e.g. at pH 1.2, which corresponds to the fasted state of the stomach, they are less effective and the release is mainly controlled by the HPMC, which is a pH-independent release-controlling agent. This behaviour results in a pH-dependent release profile , which may be disadvantageous (because of variability in the in vivo performance) particularly at stress conditions of patients, which may be associated with changes of pH in the stomach.

WO 2007/036952 discloses a sustained release formulation, which may be used for the formulation of pramipexole dihydrochloride tablets, comprising a non-swelling pH-dependent release retardant (such as poly(methacrylic acid, methyl methacrylate)) and a non-swelling pH- independent release retardant polymer (such as a mixture of polyvinyl acetate (8 parts w/w) and polyvinylpyrrolidone (2 parts w/w)), which provides a pH-independent drug release. However, this composition is not suitable in cases where a very low loading of an extremely water-soluble compound is used because of a possible burst effect.

Thus, it is desirable to develop an extended release tablet for once-a-day administration of pramipexole, having a more robust and reproducible release rate at different pHs. In particular, compositions not comprising an anionic polymer are desirable.

SUMMARY OF THE INVENTION

The present invention is based on a discovery of a new tablet composition for a controlled and pH-independent release rate of the pharmaceutically active compound pramipexole from the tablet matrix after oral administration.

Accordingly, a first aspect of the invention relates to an extended release tablet composition comprising a] a water-soluble, preferably dihydrochloride, salt of the compound (S)-N⁶-propyl- 4,5,6,7-tetrahydro-l,3-benzothiazole-2,6-diamine (pramipexole), b] at least one non-ionic, not gelling release-controlling polymer, and c] at least one non-ionic, gelling release-controlling polymer.

In an advantageous aspect, the invention provides a two-component extended release tablet composition comprising a] an active granulate comprising a water-soluble, preferably dihydrochloride, salt of the compound (S)-N⁶-propyl-4,5,6,7-tetrahydro-l,3-benzothiazole-2,6-diamine (pramipexole), at least one non-ionic, not gelling release-controlling polymer and, optionally, a water-insoluble filler/binder, and b] a tablet matrix, in which the active granulate is uniformly dispersed, said matrix comprising at least one non-ionic, gelling release-controlling polymer.

Preferably, the non-ionic not gelling release-controlling polymer is Kolidone SR, which is a mixture of polyvinyl acetate (8 parts w/w) and polyvinylpyrrolidone (2 parts w/w).

The water-insoluble filler/binder is preferably microcrystalline cellulose.

The non-ionic gelling release-controlling polymer is preferably hydroxypropyl methylcellulose (HPMC).

In a preferred aspect, the tablet composition comprises 0.1-1% pramipexole

dihydrochloride; 30-60% of non-ionic gelling polymer(s); and 2-30% of non-ionic not gelling polymer(s).

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows the dissolution curves of compositions A, B and D of the pramipexole- extended release (PAL-CR) tablets as presented in the table in the Examples section.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is based on the discovery of an extended-release pramipexole tablet composition that does not comprise ionic release-controlling polymers and still can have a similar release profile to the commercially available monolitic extended-release pramipexole tablet composition. Advantageously, such composition is a two-component composition, wherein the first component is a granulate comprising the active substance, and the second component is a polymeric matrix in which the plurality of the granulate particles is uniformly dispersed.

In compressed form, the composition forms a tablet.

The active substance is a water-soluble salt of the compound (S)-N⁶-propyl-4,5,6,7- tetrahydro-l,3-benzothiazole-2,6-diamine, which will be further denoted as pramipexole.

Preferably, the water-soluble salt is pramipexole dihydrochloride, in particular pramipexole dihydrochloride monohydrate. The amount of pramipexole is generally 0.125 to 5 mg, typically 0.125, 0.375, 0.75, 1.0, 1.5, 3.0 or 4.5 mg, calculated as pramipexole dihydrochloride

monohydrate. As a percentage of the total tablet weight the pramipexole dihydrochloride is in the range of 0.06 to 1.0%, typically 0.1 to 1.0%.

Pramipexole and water-soluble salts thereof are well known pharmaceutically active ingredients and are either commerically available and or obtainable by processes well known in the art.

The controlled release tablets / tablet compositions of the present invention comprise two kinds of release-controlling polymers: at least one non-ionic, not gelling release-controlling polymer at least one non-ionic gelling release-controlling polymer

In accordance with the general knowledge, the "gelling" and "not gelling" properties refer to the ability of a polymer to physically interact with water to form gels by swelling.

In an advantageous arrangement, the tablet composition comprising the active substance and the two kinds of release-controlling polymers is formed into two main components: a) a plurality of granules (the active granulate) comprising a water-soluble salt of pramipexole (the active substance), at least one non-ionic, not gelling release-controlling polymer and, optionally a water-insoluble filler/binder, and b) a tablet matrix, in which the above granulate particles are uniformly dispersed, said matrix comprising at least one non-ionic gelling release-controlling polymer.

Optionally, the formed tablet may be coated by a non-functional coat.

Thus, the advantageous composition of the tablet of the invention is generally characterised as comprising a hydrophilic pH-neutral swellable and gelling outer polymeric matrix, within which an active granulate comprising the active substance and a second pH- neutral non-swellable polymer are uniformly dispersed. Said outer polymeric matrix swells upon contact with water in the digestive tract, thereby creating a protective gel layer from which the active ingredient is slowly, gradually and continuously released. The amount of the active ingredient to be released in time is further modulated by the polymeric matrix present in the active granulate, which matrix does not swell to form a gel but rather slowly erodes.

According to our knowledge, no controlled-release pramipexole composition of the prior art having a therapeutically suitable release rate of the active component is based solely on non- ionic release-retarding polymers.

The combination of two non-ionic (thus pH-neutral) polymers of different behaviour (gelling and not gelling), advantageously within an intra-and intergranulation, assures that the overall release of pramipexole is pH-independent. Thus, the release of pramipexole is less dependent on the state of the stomach, which may be fed or fasted. The combination of two different mechanisms of release (slow penetration of water through the gel layer and slow erosion of the not gelling polymer in the granulate) assures a proper release rate and , in an important aspect, completness of the release. In particular, the total amount of the pramipexole released from the composition may be higher than 90%, i.e. less than 10%) of the active remains unreleased.

The advantageous feature that the active is preferably concentrated in a granulate, which may be easily uniformly dispersed within the tablet composition, assures proper dose uniformity of the tablet composition even at a relatively low loading. Importantly, the incorporation of the active substance into an inner granulate prevents an initial burst of pramipexole in the first minutes of release, which is the biggest disadvantage of monolithic tablets.

An extragranular matrix also serves as a coat protecting the pramipexole against undesired action of the environment, thus increasing the stability of the active.

The composition of the outer matrix also assures that the active granulate is not liberated from the tablet composition after ingestion. Instead, the pramipexole maintains in the tablet, which assures the desirably slow release in the body.

Thus, the composition of the present invention has many therapeutic and technological advantages.

The active granulate comprises, apart of the active substance , a non-ionic (pH-neutral) not gelling release-controlling polymer. The non-ionic not gelling polymers are generally known in the art and include cellulose derivatives, e.g. ethyl cellulose, polyacrylates , e.g. Eudragit RS or RL, polyvinyl acetate and/or polyvinylpyrrolidone, alone or in combination. Typically, the advantageous polymer of this art is Kollidon SR, which is a mixture of polyvinyl acetate (8 parts w/w) and polyvinylpyrrolidone (2 parts w/w).

Furthermore, the active granulate may comprise at least one filler/binder. Preferably, the filler/binder is insoluble in water. Typically, the advantageous filler/binder is microcrystalline cellulose.

The percentage of the non-ionic, not gelling polymer within the active granulate is typically 10-80%.

The outer tablet matrix, in which the active granulate is dispersed, is composed mostly of non-ionic gelling polymer(s), which account for 25 to 65%, more typically 30 to 60% of the weight of the tablet. The non-ionic gelling polymers are generally known in the art and include alkyl celluloses; hydroxyalkyl celluloses; polysaccharides such as galactomannanes, agar-agar, carrageen, arabic gum, and sterculia gum; polyalkylene oxides such as polyethylene oxide; polyvinylalcohols; and crosslinked polyvinylpyrrolidones, alone or in combination. Generally, hydroxypropyl methylcellulose (HPMC) is used as the only neutral polymer, albeit in one or more grades or viscosities, or is at least present as one of the neutral polymers. A single grade of HPMC may be used, typically having a viscosity of greater than 100 cps and often greater than 1,000 cps such as 10,000 to 20,000 cps. Blends of high and low viscosity HPMC may advantageously be used as well wherein the lower viscosity HPMC (usually 5-20 cps) is typically used in lower amounts than the higher viscosity HPMC.

The matrix may further comprise a solid filler/diluent, typically in an amount up to 30%, preferably 5 to 25%, of the tablet weight. The diluent includes water-soluble or water-insoluble diluents. Water-soluble diluents advantageously comprise polyols and sugars such as mannitol, sorbitol, lactose, etc., but are not limited thereto. Water-insoluble diluents advantageously comprise a cellulose or a cellulose derivative, but are not limited thereto.

The tablet composition may further comprise other excipients such as lubricant(s), glidant(s), colorant(s), pigment(s), taste masking agent(s), etc. Often the tablet composition will contain magnesium stearate as a lubricant and silicon dioxide as a glidant, each in amounts of 2% or less, typically 1% or less.

The tablets of the invention do not require starch in order to achieve the desired release and tablet hardness properties. Thus in most embodiments, pregelatinized starch is excluded from the tablets and, more preferably, all starch is excluded from the tablets. In addition, carboxymethylcellulose including carboxymethylcellulose sodium is not required in the tablets of the invention and is preferably excluded.

The tablets made from the composition of the present invention typically have a total weight of 150 to 600 mg such as 200, 250, 325, 350, 425, or 500 mg. The tablet shape is not limited and is usually round or oblong.

The tablets of the invention exhibit good extended-release of pramipexole. Generally, the tablets of the invention exhibit an average in vitro dissolution of pramipexole, when measured in simulated gastric fluid by USP method with Apparatus 3 at 5dpm, such that 25-50% is released in 2 hours; after subsequent full media change to USP phosphate buffer pH 6.8 with Apparatus 3 at 30dpm, 50-85% is released in 9 hours and more than 70% is released after 20 hours.

In a preferred embodiment the dissolution curves for tablets of the invention closely match the dissolution curve of the Sifrol^® ER product. That is using the commercial tablet as the reference standard, the tablets of the invention preferably exhibit a statistical similarity factor f₂ of at least 50, when measured under the same in vitro dissolution conditions. Likewise, the tablets are also preferably bioequivalent to Sifrol^® ER.

The tablets of the present invention with controlled release of pramipexole can be preferably made by a two-step granulation process. In a first step, in which a granulate is made, the active component is mixed with the non-ionic, not gelling polymer(s) and, optionally, with the filler/binder and granulated in the presence of a granulating liquid. The liquid, which is typically water and/or alcohol , is removed from the formed granules by drying. The granules of the active granulate are then sieved and/or milled.

The active granulate is combined with the remaining excipients of the tablet matrix, i.e. with a non-ionic, gelling polymer(s), a solid filler/diluent and, optionally, other excipients such as lubricants, glidants, colorants, pigments, taste masking agents by a wet granulation, dry granulation or dry mixing to obtain a uniform mixture. The mixture is then compressed to tablets in a suitable tablet press.

In an alternate process, the tablets may be made by a direct compression of the components.

The tablets may optionally be coated. Typically such a coating, if applied, is for color, taste masking, and/or stability reasons using conventional materials and techniques. A functional, i.e. release controlling, coating is normally not needed and preferably is avoided. Likewise enteric coatings are typically avoided.

For clarity, the weight percentages referred to herein are based on the uncoated tablet; i.e., the weight of a coating, if any, is not included. The tablets / tablet compositions of the invention are useful in medicine, for treating diseases and conditions known to be treated with pramipexole. Typically, these conditions include schizophrenia, Parkinson's disease or Parkinsonism, and/or hypertension, but is not limited thereto. By use of the tablets of the present invention, however, once-a-day dosing should be possible.

The invention will be further described with reference to the following non-limiting examples.

EXAMPLES

Composition of a tablet comprising 0.375 mg pramipexole dihydrochloride monohydrate

Process:

Mix the intragranular excipients in the high shear mixer for 5 minutes. Add slowly the granulation liquid to the stirred mixture until a granulate is formed. Dry the granulate in a fluid bed and mill the dried granulate into a suitable particle size. Mix the milled granules with the extragranular excipients, except the magnesium stearate. Add the magnesium stearate and blend for another 5 minutes. Compress this blend into a 250 mg tablet with a diameter of 9 mm.

The invention having been described, it will be readily apparent to those skilled in the art that further changes and modifications in actual implementation of the concepts and

embodiments described herein can easily be made or may be learned by practice of the invention, without departing from the spirit and scope of the invention as defined by the following claims.

Claims

An extended release tablet composition comprising a] a water-soluble, preferably dihydrochloride, salt of the compound (S)-N⁶-propyl- 4,5,6,7-tetrahydro-l,3-benzothiazole-2,6-diamine (pramipexole); b] at least one non-ionic, not gelling release-controlling polymer; and c] at least one non-ionic, gelling release-controlling polymer.

The composition according to claim 1 , wherein the non-ionic not gelling release controlling polymer is a cellulose derivative, e.g. ethyl cellulose, a polyacrylate, e.g. Eudragit RS or RL, a polyvinyl acetate and/or a polyvinylpyrrolidone, alone or in combination.

The composition according to claim 1 or 2 , wherein the non-ionic not gelling release controlling polymer is a mixture of polyvinyl acetate (8 parts w/w) and

polyvinylpyrrolidone (2 parts w/w).

The composition according to claims 1 to 3, wherein the non-ionic gelling polymer include alkyl celluloses; hydroxyalkyl celluloses; polysaccharides such as

galactomannanes, agar-agar, carrageen, arabic gum, and sterculia gum; polyalkylene oxides such as polyethylene oxide; polyvinylalcohols; and crosslinked

polyvinylpyrrolidones, alone or in combination.

The composition according to claims 1 to 4, wherein the non-ionic gelling polymer is hydroxypropyl methylcellulose, preferably having a viscosity of greater than 100 cps and more preferably more than 1,000 cps such as 10,000 to 20,000 cps. The composition according to claims 1 to 5 further comprising a filler/binder, which preferably is microcrystalline cellulose.

The composition according to claims 1 to 6, which does not comprise starch.

The composition according to claims 1 to 7, which is a two-component composition comprising a] an active granulate comprising a water-soluble, preferably dihydrochloride, salt of the compound (S)-N⁶-propyl-4,5,6,7-tetrahydro-l,3-benzothiazole-2,6-diamine

(pramipexole), at least one non-ionic, not gelling release-controlling polymer and , optionally, a water-insoluble filler/binder; and b] a tablet matrix, in which the active granulate is uniformly dispersed, said matrix comprising at least one non-ionic gelling release-controlling polymer.

The composition according to claims 1 to 8, which comprises 0.1-1.0% pramipexole dihydrochloride; 30-60% of non-ionic gelling polymer(s); and 2-30% of non-ionic not gelling polymer(s).

The composition according to claims 1 to 9, wherein the tablet is coated by a nonfunctional coat.

A tablet comprising the composition according to claims 1 to 10, which exhibits an average in vitro dissolution of pramipexole, when measured in simulated gastric fluid by USP method with Apparatus 3 at 5dpm, such that 25-50%> is released in 2 hours; after subsequent full media change to USP phosphate buffer pH 6.8 with Apparatus 3 at 30dpm, 50-85%) is released in 9 hours and more than 70% is released after 20 hours. A process for making a tablet with a controlled release of pramipexole comprising

1] a step of making a granulate, in which the active component is mixed with the non- ionic, not gelling polymer(s) and, optionally, with the filler/binder and granulated in the presence of a granulating liquid;

2] a step of combining the granulate with a non-ionic, gelling polymer(s), a solid filler/diluent and, optionally, other excipients by a wet granulation, dry granulation or dry mixing to obtain a uniform mixture; and

3] a step of compressing the uniform mixture to a tablet.

The process according to claim 12 further comprising a step of coating the tablet.

A tablet composition according to claims 1 to 10 , and/or a tablet according to claim 11 or made according to the process of claims 12 or 13, for use in medicine.