FIELD OF THE INVENTION The present invention relates to stable pharmaceutical composition of atypical antipsychotics. Particularly the present invention relates to stable pharmaceutical composition of anpiprazole. More particularly the present invention relates to stable composition of aripiprazole containing less than 0.5% by weight, compared to the total weight of the composition, of N-oxide impurity.

BACKGROUND OF THE INVENTION

Aripiprazole _. is. an . atypical . antipsychotic .used .in. the .treatment-of-schizophrenia, bipolar disorder, and clinical depression. The atypical antipsychotics (AAP) also known ' as second generation antipsychotics are a group of antipsychotic tranquilizing drugs used to treat psychiatric conditions. The most common atypical antipsychotics currently available in the market are Axipiprazole, Amisulpride, Asenapine, Clozapine, Olanzepine, Paliperidone, Perospirone, Quetiapine, Remoxipride, Risperidone, Sertindole, Sulpiride, Ziprasidone, Zotepine, Lurasidone Mosapramine, Clotiapine and Blonanserin. Aripiprazole originally marketed as. Ability and is available as tablets, orally disintegrating tablets, oral solutions and intramuscular injections. Chemically aripiprazole " ^' is 7-{4-[4-(2,3-dichlorophenyl)piperazin-l- yl]butoxy}-3,4- dihydroquinolin-2( 1H)-one.

US 2007/0154545 & EP 1 808 165 patents disclose a method of making an aripiprazole formulation comprising a mixture of aripiprazole, at least one diluent, at least one tablet binder, and at least one tablet disintegrant; blending the mixture to obtain a homogeneous mixture; optionally adding at least one tablet lubricant to the homogeneous mixture; and dry compressing the homogeneous mixture into the composition.

US 2007/0154544 & EP 1 808 164 patents disclose a method of making aripiprazole pharmaceutical compositions by wet granulation comprising a mixture of aripiprazole, at least one diluent, at least one tablet binder, and water; blending the mixture to obtain a wet granulate; drying the wet granulate at a temperature of less than 70°C to obtain a dried granulate; and milling the dried granulate to obtain a milled dried granulate, with the proviso that thejwet. ranulate, is. not..milled prior to. drying. -Further- adding- at-least - one tablet lubricant to the milled dried granulate; and compressing the milled dried granulate in a tablet press to obtain a tablet. This patent discloses a method of making aripiprazole tablets by wet granulation method; this method requires more equipment, more time, more space and more labor than the direct compression method.

US 2010/0209495 patent discloses a granulate, where the granule comprises an active pharmaceutical ingredient (API) having a poor water solubility (i.e. less than about 1 mg/mL) which is intimately associated with at least one pharmaceutically acceptable hydrophilic polymer. The granule optionally contains one or more pharmaceutically acceptable excipients, such as disintegrants, wetting agents, diluents, binders, lubricants, glidants, coloring agents and flavoring agents. The invention also relates to a process for preparing the pharmaceutical granulate and pharmaceutical compositions containing the granulate.

EP 2 036 545 patent discloses a method of making tablets by wet granulation method comprising a mixture of aripiprazole (type I and form II), lactose monohydrate, starch, microcrystalline cellulose, hydroxypropyl cellulose, and magnesium stearate. Further the tablets comprise at least one colorant. This patent discloses making of tablets by wet granulation method; this method requires more equipment, more time, more space and more labor than the direct compression method.

AU 2006/224760 & US 2006/0257471 patents disclose a pharmaceutical composition in the form of a tablet by wet granulation method, comprising 1 to 50mg of aripiprazole type II and pharmaceutically acceptable excipients including one or more fillers, one or more binders, one or more disintegrants and a lubricant. These patents disclose the improved stability on storage conditions and does not exhibit a pronounced change in release profile after storage in a variety of conditions than commercial product.

US 2007/0014854 patent discloses a granulate comprises an active pharmaceutical ingredient which has a poor solubility, associated with at least one pharmaceutically -acceptable-sugar,-and-at-least-one-phannaceutically-accepta ble-excipient-other than- me ^¬ at least one pharmaceutically acceptable sugar to form a mixture and solution comprises at least one pharmaceutically acceptable sugar and at least one solvent; drying the mixture, comminuting to obtain a pharmaceutical granulate.

US 2010/0004262 patent discloses an orally deliverable pharmaceutical composition for the controlled release of aripiprazole comprising a therapeutically effective amount of aripiprazole and at least one pharmaceutically acceptable excipient, the composition exhibiting an in-vitro release profile wherein no more than about 60% of the aripiprazole is dissolved within 3 hours of placement in a standard dissolution test.

US 2010/0297031 patent discloses an orally disintegrating tablet obtainable by direct compression of a dry powdered mixture, said mixture comprising up to 15% by weight of calcium silicate, at least 50% by weight of a diluent, at least a disintegrant; and at least an active ingredient. Said tablets disintegrate quickly in the cavity of the mouth, in particular in less than 15 seconds, US 2009/0208576 patent discloses a directly compressible composite for an orally disintegrating tablet comprising at least one water-soluble excipient and calcium silicate prepared by co-processing. EP 1 145 711 patent discloses a flash-melt pharmaceutical dosage form comprising a medicament and a combination of four excipients consisting of a super disintegrant, a dispersing agent, a distributing agent, and a binder. This patent discloses a large amount of dispersing and distributing agent in the formulation which may increase the tablet weight and also increase the formulation cost.

EP 2 359 816 patent discloses a pharmaceutical formulation, characterized by comprising aripiprazole monohydrate and super disintegrant and disintegrant mixture in which the proportion of aripiprazole monohydrate to super disintegrant and disintegrant mixture is in a range of 0.1 to 2.0.

All the above prior art documents disclose various process and compositions for preparation- of "Aripiprazole ^~ dosage - forms— None- of ^■ -the- above- prior-art- documents discloses information about stability of prepared compositions. The present inventors during development of aripiprazole compositions encountered problem of raising N- oxide impurity during stability and is crossing 1CH limits in 3 months of accelerated condition. So there is need to develop stable composition of aripiprazole. The present inventors have developed stable aripiprazole composition comprising crospovidone having peroxide content of less than 80 ppm as disintegrant and one or more pharmaceutical acceptable excipients.

BRIEF DESCRIPTION OF THE INVENTION

The present invention provides stable pharmaceutical composition of Aripiprazole, containing less than 0,5% N-oxide impurity by weight, on the basis of the total weight of the composition, wherein the composition comprises aripiprazole, crospovidone having peroxide content less than 80 ppm, and one or more suitable pharmaceutically acceptable excipients. DETAILED DESCRIPTION OF THE INVENTION

The main embodiment of the present invention is stable pharmaceutical composition of Aripiprazole.

Another embodiment of the present invention provides stable composition of aripiprazole containing less than 0,5% N-oxide impurity by weight, on the basis of the total weight of the composition, wherein the composition comprises aripiprazole, crospovidone having peroxide content less than 80 ppm, and one or more suitable pharmaceutically acceptable excipients.

In another embodiment of the present invention, the invention encompasses the use of ^■ crospovidone-having /peroxide- content of-less-than-80 ppm advantageously-less-than-SO- ppm, in a composition comprising aripiprazole, and eventually other suitable pharmaceutically acceptable excipient, to obtain a stable composition of aripiprazole. Said stable composition of aripiprazole contains less than 0,5% N-oxide impurity by weight, on the basis of the total wei ght of the composition.

In the description of this invention, the term "N-oxide" represents the N-oxide derivatives of aripiprazole. Said N-oxide derivatives result from the degradation of aripiprazole.

In the description of this invention, the term "stable" means that the quantitative composition does not significantly change over the time, during the entire shelf-life of the composition, namely for at least 3 months, advantageously for at least 6 months, more advaritageously for at least 12 months, even more advantageously for at least 36 months, under standard condition, in particular at a temperature ranging for 20°C to 40°C and a relative humidity ranging for 50% to 75%. In particular, the amount of impurities does not increase during the entire shelf-life of the composition. More specifically, N-oxide impurity level is less than 0.5% by weight, based on the total weight on the Composition, during the entire shelf life of the composition. In the present invention, the composition is advantageously stable during 6 months at a temperature of 40°C and a relative humidity of 75%.

Furthermore, the phrase "suitable pharmaceutically acceptable excipients", as used herein, means pharmaceutically acceptable excipients having peroxide content less than 80 ppm, advantageously less than 50ppm.

Crospovidone used according to the present invention should have peroxide content of less than 80 ppm, and advantageously less than 50 ppm. Peroxide increases the oxidation of aripiprazole and thereby the N-oxide formation. Thus, a low peroxide content in the composition will reduce oxidation of aripiprazole and thereby reducing N-oxide formation during shelf-life of product. Commonly available crospovidone ^" under ^" "th ^~ brand ^~ names ^~ of-Kollidon#- -and— Polyplasdone®— had-perox-ide- content- maximum of 1000 ppm. Thus, said crospovidone will not be able to stop oxidation of aripiprazole during shelf-life and thereby increasing of N-oxide formation during shelf- life and crossing limits mentioned in ICH guidelines impurities in New Drug products (ICH Q3B( 2) step 4versiofi). Polyplasdone® ultra is a new generation of ultra-pure super disintegrant having significantly lower peroxide content than standard forms of crospovidone.

In the following description, unless otherwise indicated, percentages are expressed by weight on the basis of the total weight of the composition.

The composition according to the present invention comprises between 1 % and 20% of aripiprazole, and advantageously between 5% and 15% of aripiprazole.

One or more excipients are advantageously selected from diluents, disintegrants, lubricants, glidants, sweetening agents, flavoring agents and colorants and combinations thereof.

' . ^' .

Diluents are inactive ingredients that are added to tablets and capsules in addition to the active drug. A good diluent must be inert, compatible with the other components of the composition, non^hygroscopic, relatively cheap, compatible, and preferably tasteless or pleasant tasting. Suitable diluents according to the present invention are selected from mannitol, micro crystalline cellulose, lactose, sucrose, glucose, sorbitol and dibasic calcium phosphate and combinations thereof. In the present invention, the diluent is present in an amount of about 35% to 85%, advantageously of about 40% to 80%.

^■ Disintegrants are agents added to tablet composition to promote the breakup of the tablet into the small fragments in an aqueous environment thereby increasing the available surface area and promoting a more rapid release of the drug substance. Suitable disintegrants according to the present invention are selected from crospovidone ultra, croscarmellose sodium, croscarmellose calcium, starch, sodium starch glycolate, and alginic acid and combinations thereof. Advantageously, the disintegrant is cf ospovidotie ^" ultrar In ^" the ^" present ^' invention;- the- disintegrant- is- present- in-an-amount-of- about 3% to 15%, advantageously Of about 4% to 10%.

Lubricants are agents which prevent ingredients from clumping together and from sticking to. the tablet punches or capsule filling machine. Lubricants also ensure that ^■ tablet formation and ejection can occur with low friction between the solid and die wall. Suitable lubricants according to the present invention are selected from calcium stearate, magnesium stearate, stearic acid, and talc and combinations thereof. In the present invention, the lubricant is present in an amount of about 0.5% to 5%, advantageously of about l% to 4%.

Glidants are agents these are used to promote powder flow by reducing inter particle friction and cohesion. Suitable glidants according to the present invention are selected from colloidal silicon dioxide, talc and starch.

Sweetening agents are substances that sweeten medications, food, beverages etc., and suitable sweeteners according to the present invention are selected from aspartame, sucralose, xylitol, sweefil, sweegel, saccharine, sorbitol, maltitol, and combinations thereof. In the present invention, the sweetening agent is present in an amount of about 0.5% to 5%, advantageously of about 1% to 4%. Flavoring agents are substances added to medicines and foods to improve the quality of taste. Suitable flavoring agents according to the present invention may be selected from vanilla flavor, forest fruit flavor, fruit essences, peppermint oil, spear mint oil, clove oil, orange oil, anise oil and combinations thereof. In the present invention, the flavoring agent is present in an amount of about 0.1% to 3%, advantageously of about 0.1% to 2%.

Colorants are agents which gives a special character or distinguishing quality to the ^• pharmaceutical dosage forms. Coloring may be required to increase the aesthetic appearance or identification of a particular composition. Suitable colorants according to the present invention may be selected from indigo carmine lake, iron oxide yellow and iron oxide red and combinations thereof. In the present invention, the colorant is present in an amount of about 0.01 % to 0.5%, advantageously of about 0.01 % to 0.2%. In an another embodiment, the present invention provides a process for preparing stable compositions of aripiprazole comprising aripiprazole, crospovidone having peroxide content less than 80 ppm, advantageously less than 50 ppm, and one or more suitable pharmaceutically acceptable excipients. The stable compositions are prepared by techniques known by the skilled person in the art like direct compression or wet granulation or dry granulation. The compositions may be in form of powder and may be filled in capsules or sachets or may be compressed into tablets of immediate release or orally disintegrating or modified release. The composition is advantageously in the form of tablet, and more advantageously in the form of orally disintegrating tablets.

Direct compression technique generally involves blending all ingredients in a blender for suitable time till to achieve blend uniformity and compressing into tablets of suitable size and shape.

Wet granulation technique generally involves utilization of solvents for preparation of granules. This process generally has the steps of mixing active ingredient with diluent, optionally disintegrant, granulating this mixture either by aqueous or non-aqueous granulation, drying the granulate, optionality sieving dried granules and blending dried granules with optionally further diluent, disintegrant, optionally sweetening agent, optionally flavoring agent, optionally colorant and lubricated with lubricant. Suitable solvents used according to the present invention for preparation of wet granulation are selected from water, isopropyl alcohol, methylene chloride and combinations thereof.

Dry granulation is another technique which doesn't use any solvents for preparation of granules. This process generally has the steps of mixing active ingredient with diluent, optionally - disintegrant, slugging and de-slugging and blending with optionally sweetening agent, flavoring agent, colorant and finally lubricating with lubricant.

Release - modifying-agents- are - used- to- modify ^{^}

Suitable release modifying agents may be selected from hydroxypropyl mefhylcellulose, hydroxyl propyl cellulose, ethyl cellulose, methyl cellulose, carboxy propyl methyl cellulose, polyethylene oxide, xanthan gum, guar gum, Methacrylates, polyvinyl pyrrolidone, polyvinyl chloride, polypropylene and gelatin.

The stable composition of aripiprazole according to the present invention may be used for the treatment of schizophrenia, bipolar disorder, and clinical depression.

The present invention is further illustrated by the following non limiting examples: Example 1 & 2:

Compositions of aripiprazole tablets with crospovidone having peroxide content maximum of 400 ppm and above 80 ppm.

Example 3&4:

Composition of aripiprazole tablets with crospovidone having peroxide content of less than 50 ppm.

Brief manufacturing process: Example 1 & 3:

i) Sifting: mannitol, Polyplasdone® XL-lO/Polyplasdone® ultra 10, and calcium stearate were sifted through #40mesh and iron oxide red was sifted through #lOOmesh separately and collected in polyethylene bag.

ii) Co-sifting: Aripiprazole and iron oxide were co-sifted through #20mesh and collected. iii) Co-sifting: Polyplasdone® XL- O/Polyplasdone® ultra was co-sifted with the mixture of step ii) and blended through #20mesh.

iv) Mannitol was divided into two parts; part I was sifted with the mixture of step iii) and blended through #40mesh.

v) Sifted blend of step iv) was loaded into octagonal blender and part II mannitol was added and the mixture was blended for 10 minutes. Sifted calcium stearate was added to the octagonal blender and blended for 5 minutes,

vi) Blend was compressed into tablets. Example 2 & 4:

This composition was prepared the same as that of example 1 except the aspartame and vanilla flavor were added in step ii) of example 1.

Packaging: All the compositions from Examples 1 -4 were packaged in Al/Al blisters.

Stability studies: The above packed tablets of Example 1, 2, 3 & 4 were charged for stability studies at 40°C/75% RH (relative humidity) and observed for 6 months. After 6 months, the tablets were analyzed for impurities (Related Substances) content using following validated HPLC method:

Preparation of buffer: Mix 1 ml of Trifluoroacetic acid in to 1000 ml of milli-q-water. Filter through 0.45 um membrane filter and degas it.

Preparation of mobile Phase A: Mix buffer: methanol in the ratio of 75:25 v/v respectively. Filter through 0.45 μηι membrane filter and degas it.

Preparation of mobile Phase B: Mix milli-q-water: methanol: Trifluoroacetic acid in the ratio of 50:50:0.1 v/v/v respectively. Filter tlirough 0.45 μι ^η membrane filter and degas it. Chroitiatpgraphie conditions:

Gradient Program:

imparative related substances data was given below:

From the above data it was clearly shows that in Examples 3 & 4 according to the present invention the content of aripiprazole N-oxide is below 0,5% and thus complies as per the ICH guidelines Impurities in New Drug products.