FIELD OF THE INVENTION

The present invention relates to the oral solid pharmaceutical composition comprising lamivudine or a pharmaceutically acceptable salt thereof with isomalt as a filler. The present invention also relate to the combination of lamivudine and other Anti-HIV agents.

BACKGROUND OF THE INVENTION

Lamivudine, chemically, (2/R-cis)-4-Amino-1-[2-(hydroxymethyl)-1 ,3- oxathiolan-5-yl]-2(//-/)-pyrimidinone; (-)-2'-deoxy-3'-thiacytidine; (-)-1 -[(2R,5S)-2- (hydroxymethyl)-1 ,3-oxathiolan-5-yl]cystosine; or 3TC is a reverse transcriptase inhibitor. The therapeutic uses of lamivudine and related compounds and their preparations were disclosed in WO 91/17159.

Lamivudine is also useful in the treatment of hepatitis B infection as disclosed in US RE39155. WO Patent Publication No. 92/20344 disclosed a method of treatment of HIV infection and other viral infection with lamivudine in combination with other antiviral agents such as Zidovudine, chemically 3'-azido- 3'-deoxythymidine.

Lamivudine is commercially available as 100 mg, 150 mg and 300 mg tablets; 10 mg/ml in 240 ml oral solution. It is sold under the name EPIVIR.

U.S. Patent No. 5,905,082 reported that the needle shaped crystals of form I are not favored for pharmaceutical formulation into solid dosage forms because of poor flow characteristics.

WO Patent Application Publication No. 2009/031026 described a novel pharmaceutical composition of lamivudine and cyclodextrin complex.

EP Patent No. 1 ,180,033 disclosed lamivudine, lactose, starch, crystalline cellulose, hydroxypropyl cellulose and talc in pharmaceutical formulation.

The combination composition of lamivudine and zidovudine is commercially available as 150 mg and 300 mg tablets. It is sold under the name COMBIVIR.

U.S. Patent No. 6,1 13,920 disclosed a pharmaceutical composition comprising two active pharmaceutical ingredients namely lamivudine and zidovudine and a pharmaceutically acceptable glidant ingredient in the form of a film coated tablet.

WO Patent Application Publication No. 00/18383 described antiviral combination of (S)-2-ethyl-7-fluoro-3-oxo-3,4-dihydro-2H-quinoxaline-1 - carboxylic acid isopropyl ester and zidovudine and/or lamivudine.

WO Patent Application Publication No. 96/011 10 described a combination of zidovudine, lamivudine and loviride for the treatment of HIV infections and AIDS.

WO Patent Application Publication No. 2007/068934 described combination of lamivudine with tenfovir disoproxil fumarate.

Lamivudine exhibits polymorphism Form I and Form Il are reported in US patent No. 5905082, Form III are disclosed in WO 2007/119248.

All the above mentioned patents are incorporated by references. lnspite of all the above disclosed formulations of lamivudine, still there is a need for pharmaceutical formulations that are having good flow property, good compressibility and stability in terms of polymorphic form during and after the formulation.

Thus an object of the present invention is to provide the pharmaceutical formulation of lamivudine, having good flow property, good compressibility and bulk density, which enable to have a formulation without any difficulty.

Another object of the present invention is to provide the oral tablet formulation of lamivudine with isomalt as filler, the oral solid pharmaceutical formulation being capable of avoiding capping of lamivudine with any polymorphic forms.

Another object of the present invention provides a process for preparing of lamivudine and/or in combination with other anti-Human immunodeficiency virus (anti-HIV) agents.

Another object of the present invention is to provide the pharmaceutical formulation of lamivudine in combination with other anti-HIV agents, having good flow property, good compressibility and bulk density, which enable to have a formulation without any difficulty.

Another object of the present invention is to provide suitable pharmaceutical formulation of lamivudine and/or in combination with other anti- HIV agents. Yet, another object of the present invention is to provide stable oral dosage forms of lamivudine.

DETAILED DESCRIPTION OF THE INVENTION

According to one aspect of the present invention, there is provided the oral solid pharmaceutical composition comprising lamivudine or a pharmaceutically acceptable salts thereof with isomalt as a filler and optionally one or more additional excipients.

Isomalt is a sugar substitute, a disaccharide composed of two sugars glucose and mannitol that are useful as pharmaceuticaly acceptable excipients. It is an odourless, crystalline substance containing about 5% water of crystallization.

The pharmaceutical composition of the present invention has been found to have good flow property, good compressibility and bulk density in comparison with literature oral solid dosage forms.

Surprisingly, it has been found that the pharmaceutical composition of the present invention not only display the enhanced flow characteristics and dissolution, but also display the improved characteristics associated even with polymorphic forms, which does not undergo any change in crystal structure.

Capping is the term used, when the upper or lower segment of the tablet separates horizontally, either partially or completely from the main body of a tablet and comes off as a cap, during ejection from the tablet press.

The tablet formulation of present invention is also being capable of avoiding capping of lamivudine with any polymorphic forms.

A pharmaceutical composition of the present invention may also comprise one or more other excipients such as a filler agent, a disintegrant agent, a binder, a glidant and a lubricant, preferably oral solid dosage forms.

The pharmaceutical composition may be for example, in the form of a tablet, a caplet, pellets, a capsule, granules, a pill, powder or a sachet.

Preferably, the pharmaceutical composition is in the form of a tablet and a capsule. The capsule may contain powder, compressed powder or granules.

Still more preferably, the pharmaceutical composition is in the form of a tablet.

Preferably, lamivudine used in the oral solid pharmaceutical composition is in polymorphic form I, or form II, more preferably polymorphic form I. In one embodiment of the present invention, the concentration of lamivudine to isomalt in the pharmaceutical composition is about 1 :0.2 to about 1 :4,.

More preferably, the concentration of lamivudine to isomalt in the pharmaceutical composition is about 1 :0.5 to about 1 :2.

In another embodiment, the pharmaceutical composition of the present invention comprises a filler agent, a disintegrant agent, and a lubricant, wherein said solid pharmaceutical composition comprising lamivudine is in polymorphic form I.

Excipient selection depends on various factors, such as, the choice of active ingredient percentage, the objectives of the tablet formulation development and method of manufacture. The foremost property an excipient must possess is compatibility with active ingredients.

Preferably, the pharmaceutically acceptable excipients in accordance with the invention include at least one filler agent (in addition to isomalt) and/or at least one disintegrant agent, and/or at least one lubricant.

Preferably, the filler includes calcium carbonate, dibasic calcium phosphate, lactose, magnesium carbonate, magnesium oxide, lactose anhydrous, microcrystalline cellulose, mannitol or mixtures thereof and more preferably isomalt and/or microcrystalline cellulose.

Preferably, the lubricants includes stearic acid, a salt of stearic acid, talc, sodium stearyl fumarate, calcium stearate, glyceryl behenate, magnesium silicate, magnesium trisilicate, hydrogenated castor oil or mixtures thereof and more preferably calcium stearate.

Preferably, the disintegrators includes sodium starch glycolate, starch, croscarmellose sodium, crospovidone, carboxymethyl cellulose calcium, carboxymethylcellulose sodium, magnesium aluminium silicate or mixtures thereof and more preferably crospovidone.

Preferably, the glidant includes colloidal anhydrous silica, talc or mixtures thereof.

Preferably, the binders includes hydroxypropyl cellulose, polyvinylpyrrolidone k-30, hydroxypropyl cellulose (low-substituted), starch or mixtures thereof and more preferably hydroxypropyl cellulose (low-substituted). Other ingredients such as stabilizers and antiadherants, conventionally used for pharmaceutical formulations may also be included in the present formulation.

In according to another aspect of the present invention, there is provided the process for preparing the oral solid pharmaceutical composition which comprises mixing lamivudine or pharmaceutical acceptable salts thereof, isomalt and optionally one or more additional excipients.

It has been found that the pharmaceutical process of the present invention are physically stable to pharmaceutical unit operations such as compression, thereby making oral solid dosage of the present invention amenable to pharmaceutical compounding operations, such as for example, tabletting.

In preferred embodiment, lamivudine is mixed with one or more of the other excipients such as filler (in addition to isomalt), disintegrant agent, a binder, a glident or a lubricant.

Preferably, the oral solid pharmaceutical compositions are in the form of a tablet, a caplet, pellets, a capsule, granules, a pill, powder or a sachet and more preferably a tablet.

Preferably, the tablet compositions are prepared by process of direct compression, wet granulation or slugging, more preferably direct compression.

The tablet may also be optionally coated with a coating agent.

Preferably, lamivudine used in the process for preparing the oral solid pharmaceutical composition is in polymorphic form I ₁ or form II, more preferably polymorphic form I.

A preferred embodiment of the invention suitable for forming tablet comprises in parts by weight from about 25% to about 80% lamivudine, from about 15% to about 80% isomalt and/or microcrystalline cellulose or lactose, from about 1 % to about 10% crospovidone and/or croscarmellose sodium, from about 1 % to about 10% povidone and/or hydroxypropyl cellulose, from about 0.125% to about 5% calcium stearate or magnesium stearate, from about 1% to about 4% opadry white. Optionally additional excipient/s may be used. The additional excipients include pharmaceutical lubricants, disintegrators, binders, glidants, fillers or mixtures thereof.

In according to another aspect of the present invention, there is provided the oral solid pharmaceutical composition comprising lamivudine or a pharmaceutically acceptable salt thereof with isomalt as a filler and in combination with other anti-HIV agents, optionally one or more additional excipients.

Preferbly, the other Anti-HIV agents are zidovudine, abacavir, tenfovir disoproxil fumarate or a pharmaceutically acceptable salt thereof.

Preferably, lamivudine used in the oral solid pharmaceutical composition is in polymorphic form I, or form II, more preferably polymorphic form I.

A preferred embodiment of the present invention provides stable pharmaceutical formulations of combination of i) lamivudine and zidovudine; ii) lamivudine and abacavir; or iii) lamivudine and tenfovir disoproxil fumarate.

It has been found that the pharmaceutical composition of the present invention not only display the enhanced flow characteristics and dissolution, but also display the improved characteristics associated even with polymorphic forms, which does not undergo any change in crystal structure.

A pharmaceutical composition of the present invention may also comprise one or more other excipients such as a filler agent, a disintegrant agent, a binder, a glidant and a lubricant, preferably oral solid dosage forms.

The pharmaceutical composition may be for example, in the form of a tablet, a caplet, pellets, a capsule, granules, a pill, powder or a sachet.

Preferably, the pharmaceutical composition is in the form of a tablet and a capsule. The capsule may contain powder, compressed powder or granules.

Still more preferably, the pharmaceutical composition is in the form of a tablet.

Preferably, lamivudine used in the oral solid pharmaceutical composition is in polymorphic form I, or form II, more preferably polymorphic form I.

In another embodiment, the pharmaceutical composition of the present invention comprises a filler agent, a disintegrant agent, and a lubricant, wherein said solid pharmaceutical composition comprising lamivudine is in a polymorphic form I.

Excipient selection depends on various factors, such as, the choice of active ingredient percentage, the objectives of the tablet formulation development and method of manufacture. The foremost property an excipient must possess is compatibility with active ingredients. Preferably, the pharmaceutically acceptable excipients in accordance with the invention include at least one filler agent (in addition to isomalt) and/or at least one disintegrant agent, and/or at least one lubricant.

Preferably, the filler includes calcium carbonate, dibasic calcium phosphate, lactose, magnesium carbonate, magnesium oxide, lactose anhydrous, microcrystalline cellulose, mannitol or mixtures thereof and more preferably isomalt and/or microcrystalline cellulose.

Preferably, the lubricants includes stearic acid, a salt of stearic acid, talc, sodium stearyl fumarate, calcium stearate, glyceryl behenate, magnesium silicate, magnesium trisilicate, hydrogenated castor oil or mixtures thereof and more preferably calcium stearate.

Preferably, the disintegrators includes sodium starch glycolate, starch, croscarmellose sodium, crospovidone, carboxymethyl cellulose calcium, carboxymethylcellulose sodium, magnesium aluminium silicate or mixtures thereof and more preferably crospovidone.

Preferably, the glidant includes colloidal anhydrous silica, talc or mixtures thereof.

Preferably, the binders includes hydroxypropyl cellulose, polyvinylpyrrolidone k-30, hydroxypropyl cellulose (low-substituted), starch or mixtures thereof and more preferably hydroxypropyl cellulose (low-substituted).

Other ingredients such as stabilizers and antiadherants, conventionally used for pharmaceutical formulations may also be included in the present formulation.

In according to another aspect of the present invention, there is provided the process for preparing the oral solid pharmaceutical composition, which comprises mixing lamivudine or pharmaceutically acceptable salts thereof with isomalt as filler and in combination with other Anti-HIV agents, and optionally one or more additional excipients.

Preferably, the other Anti-HIV agents are zidovudine, abacavir, tenfovir disoproxil fumarate or a pharmaceutically acceptable salt thereof.

It has been found that the pharmaceutical process of the present invention are physically stable to pharmaceutical unit operations such as compression, thereby making oral solid dosage of the present invention amenable to pharmaceutical compounding operations, such as for example, tabletting. In preferred embodiment, lamivudine is mixed with one or more of the other excipients such as filler (in addition to isomalt), disintegrant agent, a binder, a glident or a lubricant.

Preferably, the oral solid pharmaceutical compositions are in the form of a tablet, a caplet, pellets, a capsule, granules, a pill, powder or a sachet and more preferably a tablet.

Preferably, the tablet compositions are prepared by process of direct compression, wet granulation or slugging, more preferably direct compression.

The tablet may also be optionally coated with a coating agent.

Preferably, lamivudine used in the process for preparing the oral solid pharmaceutical composition is in polymorphic form I ₁ or form II, more preferably polymorphic form I.

A preferred embodiment of the invention suitable for forming lamivudine and zidovudine tablet comprises in parts by weight from about 10% to about 80 % lamivudine, from about 15% to about 50% zidovudine, from about 15% to about 80% isomalt, from about 1 % to about 10% crospovidone, from about 0.125% to about 2.5% calcium stearate and from about 1.5% to about 2.5% opadry white. Optionally additional excipient/s may be used. The additional excipients include pharmaceutical lubricants, disintegrators, binders, glidant, fillers or mixtures thereof.

A preferred embodiment of the invention suitable for forming lamivudine and tenfovir disoproxil fumarate tablet comprises in parts by weight from about 15% to about 75% lamivudine, from about 15% to about 60% tenfovir disoproxil fumarate, from about 20% to about 80% isomalt, from about 1 % to about 10% crospovidone, from about 0.125% to about 2.5% calcium stearate and from about 1.5% to about 2.5% opadry white. Optionally additional excipient/s may be used. The additional excipients include pharmaceutical lubricants, disintegrators, binders, glidant, fillers or mixtures thereof.

A preferred embodiment of the invention suitable for forming lamivudine and abacavir tablet comprises in parts by weight from about 15% to about 70% lamivudine, from about 30% to about 75% abacavir sulfate, from about 1% to 50% isomalt, from about 1 % to about 10% low-substituted hydroxypropyl cellulose, from about 1% to about 10% croscarmellose sodium, from about 3% to about 25% microcrystalline cellulose, from about 1 % to about 7% povidone K- 29/32, from about 0.125% to about 2.5% colloidal silicon dioxide, from about 0.125% to about 2.5% magnesium stearate and from about 1.5% to about 2.5% opadry white. Optionally additional excipient/s may be used. The additional excipients include pharmaceutical lubricants, disintegrators, binders, glidents, fillers or mixtures thereof.

The pharmaceutical composition may be used for the treatment of Human immunodeficiency virus (HIV) and/or hepatitis B infection.

The following examples illustrate the present invention without, however, limiting the same thereof.

EXAMPLES Example 1

Preparation of a lamivudine tablet wherein the lamivudine is present in the form of lamivudine with isomalt.

This example demonstrates a tablet composition comprising lamivudine as an active pharmaceutical ingredient and one or more pharmaceutically acceptable excipients, wherein said lamivudine is present in the form of the lamivudine with isomalt, in accordance with an embodiment of the invention. This example further demonstrates a process for preparing a solid pharmaceutical composition in accordance with an embodiment of the invention.

The tablets were prepared using the materials listed in table.

The tablets were manufactured using the procedure comprising the following steps: lamivudine, isomalt, crospovidone and calcium stearate were weighted, transferred into a blender, and mixed to form a homogeneous power mixture; the resultant mixture was compressed into tablets of appropriate weight and hardness to obtain a lamivudine tablet; and optionally, the tablets can be coated.

Lamivudine tablets blend has better flow property and bulk density, which are important parameters for formulation listed below.

The results of dissolution studies of lamivudine tablets 300 mg and 100 mg are shown below

The example demonstrates the dissolution properties of the tablet prepared in accordance with the invention.

The tablets of the examplei and commercially available lamivudine tablets (i.e., Epivir 300mg) were tested for in vitro drug release in 900ml of 0.1 N HcI using a USP-2 apparatus speed operating at 75 rpm and lamivudine tablets (i.e., Epivir-HBV 100mg) were tested for in vitro drug release in 900ml of water using a USP-2 apparatus speed operating at 50 rpm. In both cases the values for the tablets of examplei and the values for commercially available lamivudine tablets (i.e., Epivir 300mg and 100mg) were greater than 85% in 15 minutes. lamivudine tablets (example 1 ) stability studies:

Stability studies were carried out at 40 deg C/75%RH and 60 deg C for two months and were found that polymorphic form I did not undergo any transformation into other polymorphs of lamivudine. Example 2 Example 1 was repeated using isomalt in different ratio.

Example 3 Example 1 was repeated using isomalt in different ratio.

The results of dissolution studies of lamivudine tablets 300 mg are shown below

Example 4 Lamivudine tablets 100 mg, 150 mg and 300 mg

The tablets were manufactured using the procedure comprising the following steps: lamivudine, isomalt, microcrystalline cellulose, croscarmellose sodium, low-substituted hydroxy propyl cellulose, povidone K-29/32, colloidal silicon dioxide and magnesium stearate were weighted, transferred into a blender, and mixed to form a homogeneous power mixture; the resultant mixture was compressed into tablets of appropriate weight and hardness to obtain a lamivudine tablet; and optionally, the tablets can be coated.

The results of dissolution studies of lamivudine tablets 300 mg are shown below

Example 5 Lamivudine tablets 100 mg, 150 mg and 300 mg

The tablets were manufactured using the procedure comprising the following steps: lamivudine, isomalt, microcrystalline cellulose, lactose monohydrate, croscarmellose sodium was done in a rapid mixer granulator and mixed for 5 to 20 minutes. Binder solution (povidone K-29/32in purified water) is added to contents of rapid mixer granulator and mixed to get dough mass. The dough mass was dried, and dried granules passed through #18.

The blending of ingredients including above dried granules, crospovidone, and magnesium stearate were weighted, transferred into a blender, and mixed to form a homogeneous power mixture; the resultant mixture was compressed into tablets of appropriate weight and hardness to obtain a lamivudine tablet; and optionally, the tablets can be coated.

The results of dissolution studies of lamivudine tablets 300 mg are shown below

Example 6 Zidovudine 300 mg and lamivudine 150 mg tablets

The tablets were manufactured using the procedure comprising the following steps: lamivudine, zidovudine, isomalt, crospovidone and calcium stearate were weighted, transferred into a blender, and mixed to form a homogeneous power mixture; the resultant mixture was compressed into tablets of appropriate weight and hardness to obtain a lamivudine and zidovudine tablet; and optionally, the tablets can be coated.

Example 7 Tenfovir disoproxil fumarate 300 mg and lamivudine 300 mg tablets

The tablets were manufactured using the procedure comprising the following steps: lamivudine, tenfovir disoproxil fumarate, isomalt, crospovidone and calcium stearate were weighted, transferred into a blender, and mixed to form a homogeneous power mixture; the resultant mixture was compressed into tablets of appropriate weight and hardness to obtain a lamivudine and tenfovir disoproxil fumarate tablet; and optionally, the tablets can be coated.

Example 8 Abacavir 600 mg and lamivudine 300 mg tablets

The tablets were manufactured using the procedure comprising the following steps: lamivudine, abacavir sulfate, and low-substituted hydroxy propyl cellulose, croscarmellose sodium, isomalt, microcrystalline cellulose was done in a rapid mixer granulator and mixed for 5 to 20 minutes. Binder solution (povidone K-29/32 in purified- water) is added to contents of rapid mixer granulator and mixed to get dough mass. The dough mass was dried, and dried granules passed through #18.

The blending of ingredients including above dried granules, low- substituted hydroxy propyl cellulose, colloidal silicon dioxide and magnesium stearate were weighted, transferred into a blender, and mixed to form a homogeneous power mixture; the resultant mixture was compressed into tablets of appropriate weight and hardness to obtain a lamivudine and abacavir tablet; and optionally, the tablets can be coated.

Example 9

Lamivudine tablets

The tablets were manufactured using the procedure comprising the following steps: lamivudine, isomalt, crospovidone and calcium stearate were weighted, transferred into a blender, and mixed to form a homogeneous power mixture; the resultant mixture was compressed into tablets of appropriate weight and hardness to obtain a lamivudine tablet; and optionally, the tablets can be coated.