in an embodiment of the present invention , the extended release tablet comprises of active ingredient and water soluble rate controlling polymer and optionally conventional excipients including a binder . these tablets are coated with a combination of water insoluble polymer . the coating optionally includes a water soluble polymer or substance as a channeling agent . the functional coated tablets are further coated with water soluble polymer as non functional coat . according to the embodiment of the present invention the active ingredient is used as such , inclusive or exclusive of the binder , if the crystal morphology is favoring direct compression . however , if the particles are not favoring direct compression and granulation is required then it is carried out either as ‘ dry granulation ’ or as ‘ wet granulation ’. the dry granulation process involves the mixing of drug with the binder or directly with the rate controlling hydrophilic polymer or both , followed by slug formation on tablet press or using the roll compactors . the process of wet granulation includes aqueous or non aqueous granulation . the wet granulation process comprises the admixing of the active ingredient with ‘ diluent ’ or mixture of ‘ diluent ’ and rate controlling hydrophilic polymer , and granulation of the blend with the binder mass to form the wet mass followed by drying and sizing . the binder may optionally be admixed with the dry blend and granulation performed with aqueous or non aqueous solvent . the solvent for the non aqueous granulation is selected from ethanol , isopropyl alcohol and dichloromethane . according to the present invention , the pharmaceutical composition contains levetiracetam as an active ingredient . the levetiracetam may be present in an amount from about 40 % to about 80 %, more preferably form about 50 % to about 75 % by weight of extended release composition . in the preferred embodiment of the present invention levetiracetam is granulated using aqueous granulation with a binder solution . the binder used is essentially important to impart compressibility , flow property and strength / hardness . the binder can be selected from polyvinyl pyrrolidone , hydroxypropyl cellulose , hydroxypropyl methylcellulose ( low viscosity grade ), methyl cellulose , starch , pregelatinized starch , modified corn starch , polyacryl amide , poly - n - vinyl amide , sodium carboxymethyl cellulose , polyethylene glycol , gelatin , polyethylene oxide , poly propylene glycol , tragacanth , alginic acid , combinations there of and other materials known to one of ordinary skill in the art . the binder may be present in an amount from about 0 . 01 % to about 10 %, preferably from about 0 . 5 % to about 5 % by weight of the extended release composition . according to the embodiment of the present invention the active granules are blended with hydrophilic rate controlling polymer of high viscosity grade as a part of the matrix system . the high viscosity grade is the one which provide viscosity greater than 15 cps in a 2 % w / w solution . the hydrophilic rate controlling polymer in the matrix system includes hydroxyethyl cellulose , hydroxypropyl cellulose , sodium alginate , carbomer ( carbopol ™), sodium carboxymethyl cellulose , xanthan gum , guar gum , locust bean gum , poly vinyl acetate , polyvinyl alcohol and hydroxypropyl methylcellulose ( high viscosity grade ). the matrix forming polymer comprises from about 1 % to about 50 %, preferably from about 20 % to about 40 % by weight of the coated extended release composition . in yet another embodiment the present invention discloses an extended release pharmaceutical composition of levetiracetam which does not exhibit a food effect . the present invention provides an extended release compositions of levetiracetam which can be administered to a mammal ( including humans ) in fed state and which exhibits a mean ( auc fasting )/( auc fed ) of at least 0 . 80 . in particular , the present invention provides an extended release compositions of levetiracetam which can be administered to a mammal ( including humans ) in fed state and which exhibits a mean ( auc fasting )/( auc fed ) of at least 0 . 80 and / or with a lower 90 % confidence limit of at least 0 . 75 . according to the embodiment of the present invention , for definitional purposes , and specifically with respect to levetiracetam extended release compositions only , a dosage form of levetiracetam exhibits a food effect if , after dosing a population , once fasted and once fed , the mean ( auc fasting )/( auc fed ) is below the value 0 . 80 and / or the lower 90 % confidence limit for this ratio is below 0 . 75 . conversely , a dosage form of levetiracetam which does not exhibit a food effect is one which , when tested on a test population , exhibits a value for ( auc fasting )/( auc fed ) of at least 0 . 80 and / or a lower 90 % confidence limit for this value is at least 0 . 75 . the value for mean ( auc fasting )/( auc fed ) can be any value above 0 . 80 and still be within the scope of this invention , though it is preferred that it can have an upper ( mean ) limit of 1 . 25 , and / or an upper 90 % confidence limit of 1 . 40 or below . in addition to the above ingredients the extended release tablets as described here also contains the lubricant , anti adherent and a glidant . antiadherents include , by way of example and without limitation , magnesium stearate , talc , calcium stearate , glyceryl behenate , polyethylene glycols , hydrogenated vegetable oil , mineral oil , stearic acid and other materials known to one of ordinary skill in the art . glidants include cornstarch , talc , calcium silicate , magnesium silicate , colloidal silicon dioxide , silicon hydrogel and other materials known to one of ordinary skill in the art . lubricants include , by way of example and without limitation , calcium stearate , magnesium stearate , sodium stearyl fumerate , glyceryl palmitostearate , glyceryl stearate , mineral oil , stearic acid , and zinc stearate and other materials known to one of ordinary skill in the art . the glidants , lubricants and anti adherents are individually present in the range from about 0 . 01 % to about 5 % w / w of the coated tablets . preferably the glidants , anti adherents and lubricants are present in the range from about 0 . 5 % to about 4 % weight of the coated tablets , either alone or in combination . the formed extended release tablets are coated with a hydrophobic rate controlling polymeric coat and the rate controlling polymeric coat is composed of hydrophobic polymer , hydrophobic or hydrophilic plasticizer and / hydrophilic pore forming polymer ( channeling agent ). the hydrophobic film forming polymer is selected from the group consisting of cellulose ether such as ethyl cellulose , cellulose acetate , polyvinyl acetate , methacrylic acid esters neutral polymer , polyvinyl alcohol - maleic anhydride copolymers and the like . even the commercially available dispersion of film formers namely , eudragit l - 30d , eudragit ne 30d , aquacoat ecd - 30 , surelease e - 7 , eudragit rs 30d , eudragit rl 30d , etc . may be used for the purpose of providing rate controlling coat . the hydrophilic pore forming polymer in the rate controlling coat is said to be selected from copolyvidone , polyvinyl pyrrolidone , polyethylene glycols , hydroxyethyl cellulose , hydroxypropyl methylcellulose ( low viscosity grade ). in the current embodiment , the water insoluble polymer is present in an amount from 40 % to about 90 %, preferably from about 50 % to about 80 % by weight of the functional coating layer of extended release composition . the water soluble pore forming polymer is present in an amount from about 10 % to about 60 %, preferably from about 15 % to about 35 % by weight of the coating layer . additionally the coating dispersion may also comprise of plasticizer to modify the properties and characteristics of the polymers used on the coat of the compressed tablets . plasticizers useful in the invention can include , by way of example and without limitation , low molecular weight polymers , oligomers , copolymers , oils , small organic molecules , low molecular weight polyols having aliphatic hydroxyls , ester - type plasticizers , glycol ethers , poly ( propylene glycol ), multi - block polymers , single block polymers , low molecular weight poly ( ethylene glycol ), citrate ester - type plasticizers , triacetin , propylene glycol and glycerin . such plasticizers can also include ethylene glycol , 1 , 2 - butylene glycol , 2 , 3 - butylene glycol , styrene glycol , diethylene glycol , triethylene glycol , tetraethylene glycol and other poly ( ethylene glycol ) compounds , monopropylene glycol monoisopropyl ether , propylene glycol monoethyl ether , ethylene glycol monoethyl ether , diethylene glycol monoethyl , ether , sorbitol lactate , ethyl lactate , butyl lactate , ethyl glycolate , dibutylsebacate , acetyltributylcitrate , triethyl citrate , acetyl triethyl citrate , tributyl citrate and allyl glycolate . also the combination of the plasticizers can be used in the present formulation . the composition in the present embodiment preferably comprises 1 . 0 to 10 . 0 % of hydrophobic polymer per weight of the coated tablets ; optionally up to 5 % per weight of hydrophilic pore forming polymer of the coated tablets and optionally up to 2 % of plasticizer per weight of the coated tablets . according to the present invention , the non - functional coating is selected from the group of ready to form dispersion such as opadry . the opadry comprises of the hydrophilic ( low viscosity grade ) film forming polymer , suitable colorant and the opacifying agent . opacifying agent include by titanium dioxide and other materials known to one of ordinary skill in the art . colorant include , by way of example and without limitation , fd & amp ; c red no . 3 , fd & amp ; c red no . 20 , fd & amp ; c yellow no . 6 , fd & amp ; c blue no . 2 , d & amp ; c green no . 5 , d & amp ; c orange no . 5 , d & amp ; c red no . 8 , caramel , and ferric oxide , red , other f . d . & amp ; c . dyes and natural coloring agents such as grape skin extract , beet red powder , beta - carotene , annato , carmine , turmeric , paprika , and other materials known to one of ordinary skill in the art . it should be understood , that compounds used in the art of pharmaceutical formulation generally serve a variety of functions or purposes . thus , if a compound named herein is mentioned only once or is used to define more than one term herein , its purpose or function should not be construed as being limited solely to that named purpose ( s ) or function ( s ). without further description , it is believed that one of ordinary skill in the art can , using the preceding description and the following illustrative examples , make and utilize the compounds of the present invention and practice the claimed methods . the following examples are given to illustrate the present invention . it should be understood that the invention is not to be limited to the specific conditions or details described in these examples levetiracetam 500 mg was sifted through s . s . sieve of mesh 40 and was then granulated with aqueous polyvinyl pyrrolidone solution and the granulated mass was dried at 50 ° c . the dried granules were sized through s . s . sieve of 20 mesh and these granules were blended with hydroxypropyl methylcellulose , lubricated with magnesium stearate and colloidal silicon dioxide and the lubricated granules were compressed into tablets . as mentioned in table 1 the tablets of example 2 were further coated with aqueous dispersion of hydrophobic rate controlling ethyl cellulose to weight gain of 2 . 96 % w / w of the compressed tablet . following the functional coating the tablets were cured at 55 ° c . for 1 hour . levetiracetam 500 mg was sifted through s . s . sieve of mesh 40 and was then granulated with aqueous polyvinyl pyrrolidone solution and the granulated mass was dried at 50 ° c . the dried granules were sized through s . s . sieve 20 mesh and these granules were blended with hydroxypropyl methylcellulose , lubricated with magnesium stearate and colloidal silicon dioxide and lubricated granules were compressed into tablets . the compressed tablets were coated with the mixture of aqueous dispersion of ethyl cellulose and opadry to a weight gain of 9 . 60 % w / w of the compressed tablets . following the functional coating the tablets were cured at 55 ° c . for 1 hour . levetiracetam 500 mg was sifted through s . s . sieve of mesh 40 and was then granulated with aqueous polyvinyl pyrrolidone solution and the granulated mass was dried at 50 ° the dried granules were sized through s . s . sieve of 20 mesh and these granules were blended with hydroxypropyl methylcellulose , lubricated with magnesium stearate , talc and colloidal silicon dioxide and lubricated granules were compressed into tablets . the compressed tablets were coated with opadry to a weight gain of 2 % w / w of the compressed tablets . levetiracetam 500 mg was sifted through s . s . sieve of mesh 40 and was then granulated with aqueous polyvinyl pyrrolidone solution and the granulated mass was dried at 50 ° c . the dried granules were sized through s . s . sieve of 20 mesh and these granules were blended with hydroxypropyl methylcellulose , lubricated with magnesium stearate , talc and colloidal silicon dioxide and the lubricated granules were compressed into tablets . the tablets of example 5 and 6 , as mentioned in the table 4 , were coated with mixture of aqueous dispersion of ethyl cellulose and hydroxypropyl methylcellulose ( lv ; low viscosity ) in the ratio of 75 : 25 ( solid content ). the tablets were coated to target weight gain of 2 . 5 % w / w and 5 . 0 % w / w of the compressed tablets for example 5 and example 6 respectively . following the coating the tablet were cured at 65 ° c . for 1 hr . the coated tablets were further coated with opadry to a weight gain of 2 % w / w of the functional coated tablet . the extended release tablets of examples 1 to example 6 were tested for dissolution of levetiracetam using 900 ml of ph 6 . 8 phosphate buffer as dissolution media at 37 ° c . and in 40 - mesh basket ( usp type 1 ) at 100 rpm levetiracetam 750 mg was sifted through s . s . sieve of mesh 40 and was then granulated with aqueous polyvinyl pyrrolidone solution and the granulated mass was dried at 50 ° c . the dried granules are sized through s . s . sieve of 20 mesh and these granules were blended with hydroxypropyl methylcellulose and then lubricated with magnesium stearate , colloidal silicon dioxide and talc and the lubricated granules were compressed into tablets . the tablets as mentioned in the table 6 , were coated with mixture of aqueous dispersion of ethyl cellulose and hydroxypropyl methylcellulose lv in the ratio of 75 : 25 ( solid content ). the tablets were coated to target weight gain of 2 . 0 % w / w . following the coating the tablet were cured at 65 ° c . for 1 hr . the coated tablets were further coated with opadry to a weight gain of 2 % w / w of the functional coated tablet . levetiracetam 750 mg and carbopol were sifted through s . s . sieve of mesh 30 and were blended together . the blend was lubricated with glyceryl behenate , colloidal silicon dioxide and talc and the lubricated blend was compressed into tablets . levetiracetam 750 mg and kollidon sr ( polyvinyl acetate : polyvinyl pyrolidone , 8 : 2 ) were sifted through s . s sieve of mesh 30 and blended together . the blend was lubricated with glyceryl behenate , colloidal silicon dioxide and talc and the lubricated blend was compressed into tablets . the tablets as mentioned in the table 8 , were coated with mixture of aqueous dispersion of ethyl cellulose and hydroxypropyl methylcellulose ( lv ) in the ratio of 75 : 25 ( solid content ). the tablets were coated to target weight gain of 1 . 90 % w / w of the uncoated tablets . following coating the tablet were cured at 65 ° c . for 1 hr . the functional coated tablets were further coated with opadry to a weight gain of 1 . 87 % w / w of the functional coated tablet . levetiracetam 750 mg and hydroxyl propyl methyl cellulose ( hv ) were sifted through s . s . sieve of mesh 40 and blended together . the blend was compacted using a roll compactor ( chilsonator ) to form slugs . the slugs were sized in an oscillating granulator using a s . s . sieve of mesh 20 . obtained granules were lubricated with magnesium stearate , colloidal silicon dioxide and talc . the lubricated blend was compressed into tablets . the tablets as mentioned in the table 9 were coated with mixture of aqueous dispersion of ethyl cellulose and hydroxypropyl methylcellulose ( lv ) in the ratio of 75 : 25 ( solid content ). the tablets were coated to target weight gain of 1 . 78 % w / w of the uncoated tablets . following the coating the tablet were cured at 65 ° c . for 1 hr . the functional coated tablets were further coated with opadry to a weight gain of 1 . 75 % w / w of the functional coated tablet . levetiracetam 750 mg and hydroxylpropyl methylcellulose ( hv ) were sifted through s . s . sieve of mesh 40 and blended together . the blend was granulated using nonaqueous granulation using hydroxypropyl cellulose as the binder . the granulated mass was dried at 45 ° c . the dried granules were sized through s . s . sieve of mesh 20 and the granules were lubricated with magnesium stearate , talc and colloidal silicon dioxide . the lubricated blend was compressed into tablets . the tablets as mentioned in the table 10 were coated with mixture of aqueous dispersion of ethyl cellulose and hydroxypropyl methylcellulose lv in the ratio of 75 : 25 ( solid content ). the tablets were coated to target weight gain of 1 . 78 % w / w of the uncoated tablets . following the coating the tablet were cured at 65 ° c . for 1 hr . the coated tablets were further coated with opadry to a weight gain of 1 . 75 % w / w of the functional coated tablet . levetiracetam 750 mg was sifted through s . s . sieve of mesh 40 and was then granulated with non aqueous hydroxypropyl cellulose solution and the granulated mass was dried at 45 ° c . the dried granules are sized through s . s . sieve of mesh 20 and these granules were blended with hydroxyethyl cellulose and lubricated with magnesium stearate , colloidal silicon dioxide and talc . the lubricated granules were compressed into tablets . the tablets as mentioned in the table 11 , were coated with mixture of aqueous dispersion of ethyl cellulose and hydroxypropyl methylcellulose ( lv ) in the ratio of 75 : 25 ( solid content ). the tablets were coated to target weight gain of 1 . 78 % w / w . the coated tablet were cured at 65 ° c . for 1 hr . the functional coated tablets were further coated with opadry to a weight gain of 1 . 75 % w / w of the functional coated tablet . the extended release tablets of examples 8 to example 13 were tested for dissolution of levetiracetam using 900 ml of ph 6 . 8 phosphate buffer as dissolution media at 37 ° c . and in 40 - mesh basket ( usp type 1 ) at 100 rpm an in vivo study was conducted in healthy human volunteers to assess bioavailability of levetiracetam formulated as the extended release tablets of example 8 by comparison with a reference treatment with immediate release levetiracetam tablets . the study followed an open label , two - treatment , two - periods , comparative oral bioavailability study in healthy , adult , male , human subjects under fed conditions . the subjects received each of the two treatments during the course of the study , which was conducted at a single center . the subjects were given 1500 mg oral dose of levetiracetam . in the case of the ir formulation , which was provided as keppra ® tablets , two equally divided doses of 750 mg each were given at 12 hour interval beginning in the morning . in the case of the extended release formulation of example 8 , two tablets of 750 mg were given at a time in the morning . plasma levetiracetam concentrations were quantified by hplc method . samples were not diluted prior to analysis as all sample concentrations were within the limits of quantitation . pharmacokinetic parameters for levetiracetam were estimated by non compartmental methods . the parameters tmax , cmax , auc 0 → t , auc 0 →∞ were estimated during the studies and recorded in table 13 . mean plasma levetiracetam concentrations over the 36 hour assessment period are shown in fig2 . levetiracetam 750 mg was sifted through s . s . sieve of mesh 40 and was then granulated with aqueous polyvinyl pyrrolidone solution and the granulated mass was dried at 45 ° c . the dried granules are sized through s . s . sieve of mesh 20 and these granules were blended with hypermellose 2208 and lubricated with magnesium stearate , colloidal silicon dioxide and talc . the lubricated granules were compressed into tablets . the tablets as mentioned in the table 14 , were coated with mixture of aqueous dispersion of ethyl cellulose and hydroxypropyl methylcellulose ( e - 3 ) and polyethylene glycol . the tablets were coated to target weight gain of 3 . 5 % w / w . the coated tablets were cured at 65 ° c . for 1 hr . the functional coated tablets were further coated with opadry to a weight gain of 2 . 5 % w / w of the functional coated tablet . the extended release tablets of examples 16 - 18 were tested for dissolution of levetiracetam using 900 ml of ph 6 . 8 phosphate buffer as dissolution media at 37 ° c . and in 40 - mesh basket ( usp type 1 ) at 100 rpm a randomized two - treatment , two period , cross - over pharmacokinetic study was conducted in eighteen healthy , adult , male human subjects in both fast and fed conditions for the above formulations and the data obtained was compared with the data of keppra ® tablets . the following are a tabulation of the results of the study in both fast and fed conditions . comparison of data of the tablet of example 16 and keppra tablets in fasting conditions although certain presently preferred embodiments of the invention have been specifically described herein , it will be apparent to those skilled in the art to which the invention pertains that variations and modifications of the various embodiments shown and described herein may be made without departing from the spirit and scope of the invention . accordingly , it is intended that the invention be limited only to the extent required by the appended claims and the applicable rules of law .
the present invention relates to extended release pharmaceutical compositions of levetiracetam and processes for preparing the same . the extended release tablet of levetiracetam is with a core comprising of levetiracetam and water dispersible rate controlling polymer , and the tablet core is optionally functional coated comprising a combination of water non - dispersible and / or water dispersible polymer . it provides extended therapeutically effective plasma levels over a twenty four hour period with diminished incidences of neuropsychiatric adverse events by eliminating the troughs and peaks of drug concentration in a patient &# 39 ; s blood plasma . the composition also exhibits no food effect .