Oral dosage formulation containing both immediate-release and sustained-release drugs for treating neurodegenerative disorders

This application claims priority to PCT International Application No. PCT/CN2010/001519, filed Sep. 29, 2010, the entireties of which is incorporated herein by reference.

This disclosure in general relates to the field of pharmacology. More particularly, this disclosure relates to an oral dosage formulation that contains both immediate-release and sustained-release drugs for treating neurodegenerative disorders.

Neurodegenerative disorders are conditions in which cells of the brain and spinal cord are lost, which may eventually lead to central nervous system (CNS)-related dysfunction, which includes, for example, Alzheimer's disease, Parkinson's disease, Huntington's disease and etc.

Initial treatment for neurodegenerative disorders is dependent on diagnosis of the underlying condition. Currently, few therapies are available for the treatment of most neurodegenerative diseases. Therapy designed to enhance cholinergic function by inhibiting acetylcholinesterase (AChE) or by attenuating N-methyl-D-aspartate (NMDA) receptor function using 1-aminocyclohexane derivatives (e.g., memantine) has been adopted to stabilize cognitive function of the dementia patient. Recently, treatment with both 1-aminocyclohexane derivatives and acetylcholinesterase inhibitors (AChEI) have been hypothesized and demonstrated in U.S. Pat. No. 2009/0124659, which was filed by Moebius on Feb. 27, 2008. Moebius suggested that the novel combination of 1-aminocyclohexane derivatives and AChEI provides super additive effect to relieve the symptoms of dementia. The combination of drugs, are provided in one composition or in two different compositions for simultaneously or sequentially ingestion.

Current dose regimens for 1-aminocyclohexane derivatives and AChEI require patients to take more than one dose a day. This is undesirable for compliance decreases as the frequency of taking a drug increases. It also poses a difficulty for patients who start to lose cognitive function including memory to follow the dose regimens of drugs and thereby would further diminish the effects of treatment. Moreover, it is well known that certain medical conditions are most desirably treated with a dosage form that provides both immediate and extended therapeutic effects while reducing the number of doses necessary, thereby making therapy more convenient. Known examples of pharmaceutical formulations which provide both immediate and sustained-release of an active pharmaceutical ingredient may refer to U.S. Pat. No. 7,255,876 B2 to Shinoda et al. and U.S. Pat. No. 6,682,759 B2 to Lim et al. Therefore, there exists a need in this field a simple and convenient course of treatment for CNS-related dysfunction, such as dementia.

This invention address such need by providing an improved oral formulation of the two drugs proposed by Moebius (Supra), i.e., 1-aminocyclohexane derivatives and AChEI, in the improved formulation of this disclosure, one drug is designed to be released immediately upon ingestion whereas the other is designed to be released over an extended period of time. With this novel design, the course of treatment for CNS-related dysfunction such as dementia is greatly simplified by eliminating the need for a patient to take several pills either simultaneously or sequentially during the course of treatment, hence would greatly improve the effects of drugs in delaying and/or preventing the onset or progression of the disease.

As embodied and broadly described herein, disclosure herein features a novel drug formulation useful for treating disorders related to central nervous system (CNS) in a subject, particularly, the human with a CNS disorder such as dementia, Alzheimer's disease, Parkinson's disease, Huntington's disease and the like.

Therefore, it is the objective of this disclosure to provide an oral dosage formulation comprising a sustained-release portion of a first compound with a dissolution rate of releasing more than 80% of the first drug within 12 hours; an immediate-release portion of a second compound with a dissolution rate of releasing more than 80% of the second compound within 60 mins; wherein the first compound is memantine, a salt, a solvate or a mixture thereof and is present in an amount of about 1-80 mg in the formulation, and the second compound is an acetylcholinesterase inhibitor (AChEI) and is present in an amount of about 1-160 mg in the formulation.

According to specific embodiments of this disclosure, the first compound is retained in a matrix, whereas the second compound is in a form of an immediate release particle or applied as a thin film deposited over the outer surface of the sustained release portion, or a single layer of a tablet constructed in two or more layers, one of the other layers of which is the sustained-release portion. According to specific examples, the oral dosage formulation may be any of a tablet, a caplet, a bi-layer tablet, a film-coated tablet or a capsule. According to certain examples, the first compound is present in an amount of about 5-60 mg, and the second compound is present in an amount of about 5-30 mg. In some example, the first compound is present in an amount of about 23-35 mg and the second compound is present in an amount of about 8-28 mg. In still some examples, the first compound is present in an amount of about 16-24 mg and the second compound is present in an amount of about 8-12 mg. In one specific example, the first compound is present in an amount of about 28 mg and the second compound is present in an amount of about 23 mg. In another specific example, the first compound is present in an amount of about 28 mg and the second compound is present in an amount of about 10 mg. In another specific example, the first compound is present in an amount of about 20 mg and the second compound is present in an amount of about 10 mg. In one specific example, the first compound is memantine. In another specific example, the first compound is memantine HCl.

According to specific embodiments of this disclosure, the second compound or AChEI useful for the described purpose is any of galantamine, tacrine, donepezil, rivastigmine, huperzine A, zanapezil, ganstigmine, phenserine, phenethylnorcymserine, cymserine, thiacymserine, SPH 1371, ER 127528, RS 1259, a salt or a solvate thereof, an enantiomer thereof, a salt or a solvate of the enantiomer or a mixture thereof. In one specific example, AChEI is donepezil. In another example, AChEI is donepezil HCl.

By combining the first compound (i.e., memantine, a salt, a solvate or a mixture thereof) in sustained-release portion and the second compound (i.e., AChEI) in an immediate-release form in a single dosage formulation, i.e., in one tablet, the course of a treatment for a subject with a CNS disorder such as dementia or Alzheimer's disease is greatly simplified for the number of tablets the subject required to take daily may be substantially reduce to a significantly low number of one or even less than one, such as half a tablet per day or 1 tablet for every two days, in accordance with some examples of this disclosure.

The details of one or more embodiments of the invention are set forth in the accompanying description below. Other features and advantages of the invention will be apparent from the detail descriptions, and from claims.

It is to be understood that both the foregoing general description and the following detailed description are by examples, and are intended to provide further explanation of the invention as claimed.

The practices of this invention are hereinafter described in detail with respect to an oral dosage formulation, particularly, an oral dosage formulation that contains both immediate-release and sustained-release drugs for treating a CNS disorder such as dementia, Alzheimer's disease, Parkinson's disease, Huntington's disease and etc.

In accordance with one embodiment of the disclosure, the oral dosage formulation comprises a sustained-release portion of a first compound with a dissolution rate of releasing more than 80% of the first compound within 12 hours; an immediate-release portion of a second compound with a dissolution rate of releasing more than 80% of the second compound within the 60 mins; wherein the first compound is memantine, a salt or, a solvate thereof, or a mixture thereof and is present in an amount of about 1-80 mg in the formulation, and the second compound is AChEI and is present in an amount of about 1-160 mg in the formulation.

The term “salt” refers herein as a salt which is formed by the interaction of a base (such as memantine or donepezil in this disclosure) with an acid, including organic or inorganic types of acids such as hydrochloric acid, hydrobromic acid, hydroiodic acid, perchloric acid, methylsulfonic acid, sulfuric acid, nitric acid, phosphoric acid, acetic acid, propionic acid, glycolic acid, pyruvic acid, malonic acid, succinic acid, maleic acid, fumaric acid, tartaric acid, cirtic acid, benzoic acid, carbonic acid, cinnamic acid, methanesulfonic acid, ethanesulfonic acid, hydroxyehtanesulfonic acid, benzenesulfonic acid, p-toluene sulfonic acid, cyclohexanesulfamic acid, salicyclic acid, p-aminosalicyclic acid, 2-phenoxybenzoic acid and 2-acetoxybenzoic acid. In one preferred example, the salt is memantine hydrochloride. In another example, the salt is donepezil hydrochloride. The term “solvate” herein refers to a complex formed by the interaction of a compound (such as memantine or donepezil in this disclosure) with surrounding solvent molecules, such as water, ethanol, and etc. In one example, the solvate of a first compound is a memantine hydrate.

The term “acetylcholinesterase inhibitor” or “AChEI” refers herein to a drug that enhances the functions of cholinergic neurons by inhibiting the activity of acetylcholinesterase (AChE). AChEI useful for the described purpose is any of galantamine, tacrine, donepezil, rivastigmine, huperzine A, zanapezil, ganstigmine, phenserine, phenethylnorcymserine, cymserine, thiacymserine, SPH 1371, ER 127528, RS 1259, a salt or a solvate thereof, an enantiomer thereof, a salt or a solvate of the enantiomer or a mixture thereof. Suitable salts of AChEI may be formed by the interaction of any AChEI compound with an acid, such as the acids described above. In one specific example, AChEI is donepezil hydrochloride((R,S)-1-benzyl-4-[(5,6-dimethoxy-1-indanone)-2-yl]-methyl-piperidine hydrochloride).

The term “sustained-release” herein refers to the release of the therapeutic compound occurs over an extended period of time leading to lower peak plasma concentrations and/or is directed to a prolonged T max as compared to “immediate-release”. The sustained-release portion of the dosage formulation is designed to deliver memantine, a salt or a solvate thereof to the digestive system of a subject continuously over a period of time for at least an hour and preferably more than several hours. The dissolution rate is slow enough that at least about 60% of memantine, a salt or a solvate thereof remains unreleased after two hours and more preferably at least about 70% of memantine, a salt or a solvate thereof remains unreleased after two hours. In general, the memantine, a salt or a solvate thereof will be at least 80% released within 12 hours, and will be at least 90% released within 24 hours. The memantine, a salt or a solvate thereof in the sustained-release portion of the formulation is retained in a matrix that is composed by at least one polymer that includes, but is not limited to, methylcellulose (MC), ethyl cellulose (EC), hydroxypropyl cellulose (HPC), hydroxypropyl methylcellulose (HPMC), carboxyl methylcellulose (CMC), microcrystalline cellulose, cellulose acetate, cellulose propionate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate phthalate, cellulose triacetate, polymethyl methacrylate, polyethyl methacrylate, polyethylene glycol, polyvinyl alcohol, polyvinyl acetate, polyvinyl alcohol-ethylene glycol, carbomer and a combination thereof. Suitable polymer(s) for producing the matrix are those sold under the trademark that includes, but is not limited to, CELPHERE® CP708, EUDRAGIT®, OPADRY®, ACRYL-EZE®, SURELEASE®, METHOCEL®, ETHOCEL®, or SURETERIC®.

The term “T max ” as used herein means the time to reach maximum plasma concentration of the active compound or drug (e.g., memantine or AchEl) achieved by the ingestion of the composition of this invention.

The sustained-release portion may be prepared by mixing memantine, a salt, a solvate or a mixture thereof with the matrixpolymer described above and suitable binders, then directly compressing the mixture into tablets. Alternatively, the sustained-release portion may contain sustained-release fine particles or pellets that are produced by any known method such as wet granulation or dry granulation method. In one example, the sustained-release fine particles or pellets are produced by wet granulation, particularly, fluid bed granulation. Wet granulation generally involves the steps of mixing the drug, the matrix polymer as described above, a diluent and a binder solution, drying the moist granules, and screening through a suitable sieve to produce particles with desired sizes. Useful binders include, but are not limited to, acacia, tragacanth, alginic acid, sodium alginate, carbomer, carboxymethylcellulose sodium, carrageenan, cellulose acetate phthalate, ceratonia, copovidone, dextrates, dextrin, dextrose, methylcellulose, ethylcellulose, carboxymethyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl cellulose; hydroxyethylmethyl cellulose; hydroxypropyl cellulose; hydroxypropyl starch; hypromellose, gelatin, starch, sucrose, lactose, magnesium aluminum silicate, maltodextrin, maltose, microcrystalline cellulose, polyvinyl pyrrolidone, polyacrylamide, povidone and pregelatinized starch. Useful diluents include, but are not limited to, ammonium alginate, calcium carbonate, calcium phosphate dibasic, calcium phosphate tribasic, calcium sulfate, cellulose, cellulose acetate, compressible sugar, dextrates, dextrin, dextrose, erythritol; ethylcellulose, fructose, fumaric acid, glyceryl palmitostearate, lactitol, lactose, mannitol, magnesium carbonate, magnesium oxide, maltodextrin, maltose, microcrystalline cellulose, polydextrose, polymethacrylates, sodium chloride, sorbitol, starch, sucrose, sugar spheres, ARBOCEL A300®; LUDIPRESS®; and SUPER TAB®. In certain examples, the sustained-release portion is prepared by mixing memantine, a salt, a solvate or a mixture thereof with a sugar sphere made of microcrystalline cellulose (e.g., CELPHERE® CP708), and at least one other matrix polymer as described above, to form memantine containing granules or pellets. Then, each of the memantine containing pellets is coated with a sustained-release film containing at least a matrix polymer described above (e.g., EUDRAGIT®), a diluent (e.g., talc) and a stabilizer (e.g., triethyl citrate) to produce the sustained-release portion or the SR portion. Optionally, the SR portion may be further coated with a protective coating to delay the release of the active ingredient therein. The protective coating may comprise at least one of the matrix polymer as described above. In one example, the protective coating comprises hydroxymethyl cellulose and polyethylene glycol. In another example, the protective coating comprises triethyl citrate (TEC) and talc. The SR coating and the protective coating may be applied as a film respectivley depositied over the sustained-release pellets and the sustained-release portion, by any known techniques such as spraying, dipping, or pan-coating.

The immediate-release portion of the dosage formulation is designed to rapidly disintegrate upon contacting a fluid such as water and allow fast leaching out of AChEI to the environment continuously over a short period of time, such as several minutes or in an hour. The dissolution rate is fast enough that at least 80% of AChEI is released within the first 60 mins. In general, at least 90% of AChEI will be released within 2 hours. The AChEI in the immediate-release portion is in a form of an immediate-release particle or applied as a thin film deposited over the outer surface of the sustained release portion, or a single layer of a tablet constructed in two or more layers, one of the other layers of which is the sustained-release portion. The immediate-release particles may be produced by any known method, such as dry or wet granulation method as described above. In one example, AChEI is mixed with disintegrants and/or binders, and adsorbents and then the mixture is subjected to either fluid bed granulation or spray drying to produce particles with desired immediate-release property. Examples of disintegrants include, but are not limited to, cross-linked polyvinyl pyrrolidone or crospovidone, starch derivatives such as carboxy methyl cellulose and cellulose derivatives; calcium alginate; carboxymethylcellulose calcium; carboxymethylcellulose sodium; croscarmellose sodium; docusate sodium; hydroxypropyl cellulose; magnesium aluminum silicate; methylcellulose; polacrilin potassium; sodium alginate; sodium starch glycolate and pregelatinized starch. Examples of adsorbents include, but are not limited to, aluminum hydroxide adjuvant; aluminum oxide; aluminum phosphate adjuvant; attapulgite; bentonite; powdered cellulose; colloidal silicon dioxide; hectorite; kaolin; magnesium aluminum silicate; magnesium carbonate; microcrystalline cellulose; pectin; polycarbophil; and saponite. At least 50% of the immediate-release particles thus prepared have a size that may pass 80 mesh; preferably, 60 mesh; more preferably, 40 mesh; and most preferably, 20 mesh.

According to specific embodiments, the sustained-release portion and the immediate-release portion respectively prepared by steps as described above are combined with glidants and lubricants to form the oral dosage formulation of this disclosure. Suitable glidants include, but are not limited to, calcium phosphate, tribasic; calcium silicate; cellulose, powdered; colloidal silicon dioxide; magnesium silicate; magnesium trisilicate; silicon dioxide; starch and talc. Suitable lubricants include, but are not limited to, calcium stearate; glyceryl behenate; glyceryl palmitostearate; magnesium lauryl sulfate; magnesium stearate; polyethylene glycol; potassium benzoate; sodium lauryl sulfate; sodium stearyl fumarate; stearic acid; talc and zinc stearate. The oral dosage formulation of this disclosure may be in a form of tablets, caplets, bi-layer tablets, film-coated tablets, pills, capsules or the like. Tablets in accordance with this disclosure can be prepared by any mixing and tabletting techniques that are well known in the pharmaceutical formulation industry. In some examples, the dosage formulation is fabricated by direct compressing the respectively prepared sustained-release portion and the immediate-release portion by punches and dies fitted to a rotary tabletting press, ejection or compression molding or granulation followed by compression. In one example, the dosage form is a single layer tablet containing therein both the sustained-release and the immediate-release portions. In another example, the dosage form is a tablet containing two layers, with one layer being the immediate-release portion and the other layer being the sustained-release portion. In still another example, the dosage form is a film-coated tablet having a sustained-release portion and a thin film of the immediate-release portion deposited over the outer surface of the sustained-release portion. The immediate-release portion may be applied as a coating over the sustained-release portion by any known techniques such as spraying, dipping, or pan-coating, or as an additional layer by tabletting or compressing in the same manner as the sustained-release portion. In some examples, the tablet is a scoring tablet having a score line at the center of the tablet for breaking the tablet into two equal halves when necessary. In other examples, the oral dosage formulation is in a form of capsule containing therein both the sustained-release particles or pellets of the first compound (i.e., memantine, a salt, a solvate, or a mixture thereof) and the immediate-release particles or pellets of the second compound (i.e., AChEI, a salt or a solvate thereof, an enantiomer thereof, a salt or a solvate of the enantiomer or a mixture thereof).

Specific examples of the oral dosage formulation of this disclosure include about 1-80 mg of memantine, a salt, a solvate or a mixture thereof, such as 5-60 mg, 23-35 mg or 16-24 mg of memantine, a solvate or a mixture thereof; and about 1-160 mg of AChEI, a salt or a solvate thereof, an enantiomer thereof, a salt or a solvate of the enantiomer or a mixture thereof, such as 5-30 mg, 8-28 mg or 8-12 mg of AChEI, a salt or a solvate thereof, an enantiomer thereof, a salt or a solvate of the enantiomer or a mixture thereof. In one example, memantine, a solvate or a mixture thereof is present in an amount of about 28 mg/dosage formulation, and AChEI, a salt or a solvate thereof, an enantiomer thereof, a salt or a solvate of the enantiomer or a mixture thereof is present in an amount of about 23 mg/dosage formulation. In another example, memantine, a salt, a solvate or a mixture thereof is present in an amount of about 28 mg/dosage formulation, and AChEI, a salt or a solvate thereof, an enantiomer thereof, a salt or a solvate of the enantiomer or a mixture thereof is present in an amount of about 10 mg/dosage formulation. In still another example, memantine, a salt, a solvate or a mixture thereof is present in an amount of about 20 mg/dosage formulation, and AChEI, a salt or a solvate thereof, an enantiomer thereof, a salt or a solvate of the enantiomer or a mixture thereof is present in an amount of about 10 mg/dosage formulation.

It must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in the respective testing measurements. As used herein, the term “about” generally means within 10%, 5%, 1%, or 0.5% of a given value or range. Alternatively, the term “about” means within an acceptable standard error of the mean, when considered by one of ordinary skill in the art dictates otherwise. Except for particular values described in the examples, or unless otherwise stated, when referring to a specified weight, a period of time, temperature, operating condition, amount and etc, the particular value is modified with the term “about.” Thus, unless otherwise indicated, where particular values are described in the application and claims, the particular value is an approximation and may vary according to various needs.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice of the present invention, exemplary methods and materials are described for illustrative purposes.

The following Examples are provided to illustrate certain aspects of the present invention and to aid those of skilled in the art in practicing this invention. These Examples are in no way to be considered to limit the scope of the invention in any manner.