naproxen sodium ( 50 kg ), citric acid ( 14 . 286 kg ), sodium lauryl sulphate ( 1 . 071 kg ) and talc ( 3 . 571 kg ) were blended and milled through a suitable mesh screen so as to obtain a homogenous powder . the powder was applied to starch / sugar seeds ( 0 . 3 - 0 . 425 mm diameter ) ( 4 . 286 kg ) using a freund cf granulator and a coating solution of 3 . 5 % polyvinylpyrrolidone in isopropanol to form the cores . a membrane was then applied to the cores by spraying on a solution consisting of : ______________________________________12 . 5 % eudragit rs in 50 parts by weightacetone / isopropanol 40 : 6012 . 5 % eudragit rl in 40 parts by weightacetone / isopropanol 40 : 6012 . 5 % eudragit l in 10 parts by weightacetone / isopropanol 40 : 60isopropanol 100 parts by weight______________________________________ while at the same time but separately dusting on talc ( 100 parts by weight ) in conventional manner . the ratio of membrane solution to talc applied was 0 . 62 grams of talc per gram of membrane solution . a sufficient amount of membrane solution and talc was applied to 76 . 214 kg of cores to achieve the dissolution profile given below . the finished pellets were dried to evaporate all solvents prior to performing the dissolution profile . a wet granulation of naproxen sodium ( 29 . 100 kg ) and polyvinylpyrrolidone ( k30 ) ( 0 . 900 kg ) was prepared by adding isopropanol ( 8 . 2351 kg ) slowly with mixing . mixing was continued until a uniform mass was produced . the granulation was dried for a minimum of 12 hours at a temperature of not less than 45 ° c . the dried granulation was then passed through an oscillating granulator . naproxen sodium pellets ( 27 . 216 kg ) and naproxen granulate ( 8 . 112 kg ) were blended with additional tableting excipients : slight adjustments may be made in the above quantities to ensure a target tablet potency of 500 mg of naproxen . the naproxen tablets were coated with an aqueous film coat . to do so , 0 . 350 kg of opadry white oy - d - 7192 was weighed and slowly added with mixing to 1 . 400 kg of purified water . mixing was continued for 30 minutes . 10 kg of uncoated tablets were weighed and placed in an accela - cota . the coating was sprayed onto the tablets at a rate of 30 - 70 g per minute until coating was complete . the dissolution rate of the pellets prepared above , prior to mixing with the granulate , was tested by the method of the u . s . pharmacopoeia xxii basket method in phosphate buffer at ph 7 . 2 at 75 r . p . m . the naproxen sodium was quantitatively determined using u . v . spectrophotometry at 331 nm . the dissolution rate of the coated tablets was tested and determined to be as follows : when tested by the method of the u . s . pharmacopoeia xxii paddle method in phosphate buffer at ph7 . 4 and at 50 r . p . m ., the dissolution rate for the pellets was as follows : naproxen sodium ( 15 . 41 kg ), citric acid ( 4 . 40 kg ) and talc ( 0 . 200 kg ) were blended and milled through a suitable mesh screen to obtain a homogeneous powder . this powder blend was layered into spherical cores using a freund cf granulator or a glatt and a coating solution of 12 . 5 % eudragit rs in isopropanol . a membrane was then applied to the cores by spraying on a solution consisting of : ______________________________________12 . 5 % eudragit rs in 70 parts by weightacetone / isopropanol12 . 5 % eudragit rl in 10 parts by weightacetone / isopropanol 40 : 6012 . 5 % eudragit l in 20 parts by weightacetone / isopropanol 40 : 60isopropanol 100 parts by weight______________________________________ while at the same time but separately dusting on talc ( 40 parts by weight ) in the conventional manner . the ratio of membrane solution to talc applied was 0 . 25 grams of talc per gram of membrane solution . a sufficient amount of membrane solution and talc was applied to 20 . 00 kg of cores to achieve the dissolution profile given below . the finished pellets were dried to evaporate all solvents prior to performing the dissolution test . a wet granulation of naproxen sodium ( 9 . 700 kg ) and polyvinylpyrrolidone ( k30 ) ( 0 . 300 kg ) was prepared by adding isopropanol ( 2 . 745 kg ) slowly with mixing . mixing was continued until a uniform mass was produced . the granulation was dried for a minimum of 12 hours at a temperature of not less than 45 ° c . the dried granulation was then passed through an oscillating granulator . naproxen sodium pellets ( 24 kg ) and naproxen granulate ( 7 . 9 ) kg ) were blended with additional tableting excipients : ______________________________________microcrystalline cellulose 4 . 63 kgcrosspovidone 0 . 76 kgmagnesium stearate 0 . 19 kgpvp k30 0 . 76 kg______________________________________ slight adjustments may be made in the above quantities to ensure a target tablet potency of 500 mg of naproxen . the naproxen tablets were coated with an aqueous film coat . to do so , 0 . 350 kg of opadry white oy - d - 7192 was weighed and slowly added with mixing to 1 . 400 kg of purified water . mixing was continued for 30 minutes . 10 kg of uncoated tablets were weighed and placed in an accela - cota . the coating was sprayed onto the tablets at a rate of 30 - 70 g per minute until coating was complete . the dissolution rate of the pellets prepared above , prior to mixing with the granulate , was tested by the method of the u . s . pharmacopoeia xxii basket method in phosphate buffer at ph 7 . 2 at 75 r . p . m . the naproxen sodium was quantitatively determined using u . v . spectrophotometry at 331 nm . the dissolution rate of the coated tablets was tested and determined to be as follows : when tested by the method of the u . s . pharmacopoeia xxii paddle method in phosphate buffer at ph 7 . 4 and at 50 r . p . m ., the dissolution rate for the pellets was as follows : naproxen sodium ( 25 kg ), citric acid ( 7 . 141 kg ) and talc ( 0 . 325 kg ) were blended and milled through a suitable mesh screen so as to obtain a homogenous powder . this powder blend was divided into two portions and layered into spherical cores using a freund cf granulator or a glatt and a coating solution of 12 . 5 % eudragit rs in isopropanol . a membrane was then applied to the cores by spraying on a solution consisting of : ______________________________________12 . 5 % eudragit rs in 75 parts by weightacetone / isopropanol 40 : 6012 . 5 % eudragit rl in 25 parts by weightacetone / isopropanol 40 : 60isopropanol 100 parts by weight______________________________________ while at the same time but separately dusting on talc ( 10 parts by weight ) in the conventional manner . the ratio of membrane solution to talc applied was 0 . 06 grams of talc per gram of membrane solution . a sufficient amount of membrane solution and talc was applied to 32 . 4 kg of cores to achieve the dissolution profile given below . the finished pellets were dried to evaporate all solvents prior to performing the dissolution test . a wet granulation of naproxen sodium ( 19 . 400 kg ) and polyvinylpyrrolidone ( k30 ) ( 0 . 600 kg ) was prepared by adding isopropanol ( 1 . 529 kg ) slowly with mixing . mixing was continued until a uniform mass was produced . the granulation was dried for a minimum of 12 hours at a temperature of not less than 45 ° c . the dried granulation was then passed through an oscillating granulator . naproxen sodium pellets ( 25 kg ) and naproxen granulate ( 7 . 85 kg ) were blended with additional tableting excipients : ______________________________________microcrystalline cellulose 6 . 00 kgcrosspovidone 0 . 815 kgmagnesium stearate 0 . 200 kgpvp k30 0 . 815 kg______________________________________ slight adjustments may be made in the above quantities to ensure a target tablet potency of 500 mg of naproxen . the naproxen tablets were coated with an aqueous film coat . to do so , 0 . 350 kg of opadry white oy - d - 9400 was weighed and slowly added with mixing to 1 . 400 kg of purified water . mixing was continued for 30 minutes . 10 kg of uncoated tablets were weighed and placed in an accela - cota . the coating was sprayed onto the tablets at a rate of 30 - 70 g per minute until coating was complete . the dissolution rate of the pellets prepared above , prior to mixing with the granulate , was tested by the method of the u . s . pharmacopoeia xxii basket method in phosphate buffer at ph 7 . 2 at 75 r . p . m . the naproxen sodium was quantitatively determined using u . v . spectrophotometry at 331 nm . the dissolution rate of the coated tablets was tested and determined to be as follows : naproxen acid ( 50 kg ), citric acid ( 15 . 64 kg ), sodium lauryl sulphate ( 0 . 071 kg ) and talc ( 0 . 500 kg ) were blended and milled through a suitable mesh screen to obtain a homogeneous powder . this powder blend was layered into spherical cores using a freund cf granulator or a glatt and a coating solution of 12 . 5 % eudragit rs in isopropanol . a membrane was then applied to the cores by spraying on a solution consisting of : ______________________________________12 . 5 % eudragit rs in 90 parts by weightacetone / isopropanol 40 : 6012 . 5 % eudragit rl in 10 parts by weightacetone / isopropanol 40 : 60isopropanol 100 parts by weight______________________________________ while at the same time but separately dusting on talc ( 20 parts by weight ) in the conventional manner . the ratio of membrane solution to talc applied was 0 . 125 grams of talc per gram of membrane solution . a sufficient amount of membrane solution and talc was applied to 66 . 22 kg of cores to achieve the dissolution profile given below . the finished pellets were dried to evaporate all solvents prior to performing the dissolution test . the dissolution rate of the pellets was tested by the method of the u . s . pharmacopoeia xxii basket method in phosphate buffer , at ph 7 . 2 at 75 r . p . m . the naproxen was quantitatively determined using u . v . spectrophotometry at 331 nm . a membrane was then applied to the cores by spraying on a suspension of : ______________________________________30 % eudragit rs in water 30 parts by weight30 % eudragit rl in water 6 parts by weighttalc 6 parts by weightwater 50 parts by weight______________________________________ the remaining 8 parts by weight were made up by a 9 : 1 mixture of tributylacetyl citrate , a plasticizer , and simethicone , an antifoam agent . a sufficient amount of membrane solution was applied to achieve the following desired release rate . a membrane was then applied to the cores by spraying on a suspension of : ______________________________________30 % eudragit rs in water 40 parts by weight30 % eudragit rl in water 2 parts by weighttalc 6 parts by weightwater 50 parts by weight______________________________________ the remaining 2 parts by weight were made up by a 9 : 1 mixture of tributylacetyl citrate , a plasticizer , and simethicone , an antifoam agent . a sufficient amount of membrane solution was applied to achieve the desired release rate of : naproxen sodium ( 30 . 0 kg ), citric acid ( 5 . 00 kg ) and talc ( 0 . 400 kg ) were blended and milled through a suitable mesh screen to obtain a homogeneous powder . this powder blend was layered into spherical cores using a freund cf granulator or a glatt and a coating solution of 12 . 5 % eudragit rs in isopropanol . a membrane was then applied to the cores by spraying on a solution consisting of : ______________________________________12 . 5 % eudragit rs in 85 parts by weightacetone / isopropanol 40 : 6012 / 5 % eudragit rl in 15 parts by weightacetone / isopropanol 40 : 60isopropanol 100 parts by weight______________________________________ while at the same time but separately dusting on talc ( 40 parts by weight ) in the conventional manner . the ratio of membrane solution to talc applied was 0 . 25 grams of talc per gram of membrane solution . a sufficient amount of membrane solution and talc was applied to 35 . 4 kg of cores to achieve the dissolution profile given below . the finished pellets were dried to evaporate all solvents prior to performing the dissolution test . a wet granulation of naproxen sodium ( 14 . 550 kg ) and polyvinylpyrrolidone ( k30 ) ( 0 . 450 kg ) was prepared by adding isopropanol ( 4 . 116 kg ) slowly with mixing . mixing was continued until a uniform mass was produced . the granulation was dried for a minimum of 12 hours at a temperature of not less than 45 ° c . the dried granulation was then passed through an oscillating granulator . naproxen sodium pellets ( 35 . 0 kg ) and naproxen granulate ( 8 . 10 kg ) were blended with additional tableting excipients : ______________________________________microcrystalline cellulose 8 . 346 kgcrosspovidone 1 . 077 kgmagnesium stearate 0 . 270 kgpvp k30 1 . 077 kg______________________________________ slight adjustments may be made in the above quantities to ensure a target tablet potency of 750 mg of naproxen . the naproxen tablets were coated with an aqueous film coat . to do so , 0 . 350 kg of opadry white oy - 9400 was weighed and slowly added with mixing to 1 . 400 kg of purified water . mixing was continued for 30 minutes . 10 kg of uncoated tablets were weighed and placed in an accela - cota . the coating was sprayed onto the tablets at a rate of 30 - 70 g per minute until coating was complete . the dissolution rate of the pellets prepared above , prior to mixing with the granulate , was tested by the method of the u . s . pharmacopoeia xxii basket method in phosphate buffer at ph 7 . 2 at 75 r . p . m . the naproxen sodium was quantitatively determined using u . v . spectrophotometry at 331 nm . the dissolution rate of the coated tablets was tested and determined to be as follows : naproxen sodium ( 22 . 5 kg ), citric acid ( 1 . 125 kg ) and talc ( 0 . 251 kg ) were blended and milled through a suitable mesh screen to obtain a homogeneous powder . this powder blend was layered into spherical cores using a freund cf granulator or a glatt and a coating solution of 12 . 5 % eudragit rs in isopropanol . a membrane was then applied to the cores by spraying on a solution consisting of : ______________________________________12 . 5 % eudragit rs in 70 parts by weightacetone / isopropanol 40 : 6012 . 5 % eudragit rl in 10 parts by weightacetone / isopropanol 40 : 6012 . 5 % eudragit l in 20 parts by weightacetone / isopropanol 40 : 60isopropanol 100 parts by weight______________________________________ while at the same time but separately dusting on talc ( 5 parts by weight ) in the conventional manner . the ratio of membrane solution to talc applid was 0 . 03 grams of talc per gram of membrane solution . a sufficient amount of membrane solution and talc was applied to 12 . 48 kg of cores to achieve the dissolution profile given below . the finished pellets were dried to evaporate all solvents prior to performing the dissolution test . a wet granulation of naproxen sodium ( 14 . 55 kg ) and polyvinylpyrrolidonne ( k30 ) ( 0 . 45 kg ) was prepared by adding isopropanol ( 1 . 147 kg ) slowly with mixing . mixing was continued until a uniform mass was produced . the granulation was dried for a minimum of 12 hours at a temperature of not less than 45 ° c . the dried granulation was then passed through an oscillating granulator . naproxen sodium pellets ( 12 . 0 kg ) and naproxen granulate ( 3 . 986 kg ) were blended with additional tableting excipients : ______________________________________microcrystalline cellulose 2 . 32 kgcrosspovidone 0 . 58 kgmagnesium stearate 0 . 10 kgpvp k30 0 . 39 kg______________________________________ slight adjustments may be made in the above quantities to ensure a target tablet potency of 750 mg of naproxen . the naproxen tablets were coated with an aqueous film coat . to do so , 0 . 350 kg of opadry white oy - d - 7192 was weighed and slowly added with mixing to 1 . 400 kg of purified water . mixing was continued for 30 minutes . 10 kg of uncoated tablets were weighed and placed in an accela - cota . the coating was sprayed onto the tablets at a rate of 30 - 70 g per minute until coating was complete . the dissolution rate of the pellets prepared above , prior to mixing with the granulate , was tested by the method of the u . s . pharmacopoeia xxii basket method in phosphate buffer at ph 7 . 2 at 75 r . p . m . the naproxen sodium was quantitatively determined using u . v . spectrophotometry at 331 nm . the dissolution rate of the coated tablets was tested and determined to be as follows : the naproxen formulation prepared in example 1 was evaluated in vivo under steady state conditions . a steady state study was performed in 18 healthy male volunteers , comparing the formulation of example 1 with selected reference products , i . e ., conventional immediate release tablets . the formulation of example 1 was administered as a single tableted dose of 1 , 000 mg of naproxen at 0 hours on days 1 - 7 , while reference naprosyn ( n ), a commercially available naproxen formulation manufactured by syntex which is administered twice daily , was administered as a single 500 mg tablet at 0 and 12 hours ( i . e . b . i . d .) on days 1 - 7 and reference synflex ( s ), a commercially available naproxen sodium formulation manufactured by syntex which is administered three to four times daily , was administered as a single 250 mg dose at 0 , 6 , 12 and 18 hours ( i . e . q . i . d .) on days 1 - 7 . plasma was sampled out to 24 hours and the mean results were calculated and tabulated . the results are illustrated in the accompanying figure . in the figure , curve a ) corresponds to a naproxen formulation prepared according to example 1 ; curve b ) corresponds to reference ( n ); and curve c ) corresponds to reference ( s ). the data presented in table 1 are from day 7 sampling . table 1______________________________________mean naproxen concentrations ( ug / ml ) - day 7 formulation ofhour reference ( n ) reference ( s ) example 1______________________________________0 . 0 46 . 95 59 . 80 42 . 390 . 50 86 . 41 84 . 92 74 . 951 . 00 102 . 09 94 . 33 84 . 892 . 00 99 . 33 77 . 63 90 . 154 . 00 76 . 38 65 . 05 93 . 096 . 00 63 . 34 53 . 90 91 . 226 . 50 59 . 20 58 . 21 87 . 267 . 00 57 . 10 68 . 53 88 . 488 . 00 52 . 76 72 . 98 80 . 6410 . 00 48 . 56 69 . 52 69 . 0212 . 00 41 . 16 57 . 07 65 . 6812 . 50 55 . 27 62 . 46 63 . 5213 . 00 67 . 12 72 . 45 60 . 8314 . 00 83 . 94 74 . 81 57 . 7816 . 00 80 . 05 67 . 10 51 . 2618 . 00 68 . 39 55 . 96 44 . 3718 . 50 63 . 09 66 . 89 45 . 8419 . 00 62 . 14 74 . 40 44 . 6320 . 00 58 . 99 72 . 92 42 . 8922 . 00 53 . 39 68 . 11 39 . 9724 . 00 47 . 90 61 . 38 38 . 30______________________________________ the results of this in vivo comparison of the formulation of example 1 against conventional immediate release tablets ( references n and s ) indicate the formulation of example 1 to be bioequivalent ( 99 . 28 %) to reference n and bioequivalent ( 95 . 46 %) to reference s . both example 1 and reference s formulations use the sodium salt of naproxen , the reference n formulation , however , uses the free acid form of naproxen . generally , peak plasma concentrations following administration of naproxen as its sodium salt are higher and are attained more rapidly than those following administration of naproxen as the free acid , hence the use of the sodium salt in the conventional form as an analgesic on a more frequent dosing regimen ( 3 - 4 times daily ). the tmax value of the formulation of the present invention of 5 . 0 hours was significantly longer than that of reference n at 1 . 36 hours , thus demonstrating the improved suitability of the present formulations in terms of maintaining naproxen plasma levels important for continued analgesia and anti - inflammatory effects up to 24 hours following administration . furthermore , the formulation of example 1 exhibited an extended mean plasma profile with adequate duration of time cover in the range of desired therapeutic plasma naproxen concentrations of 30 - 60 mcg / ml . also , the mean cmax value of the product of example 1 was close to the cmax values of the references , indicating that the sustained release characteristics of example 1 did not adversely affect the maximum plasma levels attained following administration of the formulation . a gastric tolerability questionnaire was completed by each subject on each day of the study . the results indicated a 47 % reduction in adverse gastrointestinal effects for the formulation prepared according to example 1 when compared to those recorded by reference n or s . the clinical efficacy of the naproxen formulation according to the present invention was evaluated in osteoarthritic patients . in osteoarthritis , nsaid &# 39 ; s are primarily used for their analgesic rather than their anti - inflammatory effect , although inflammation may be part of the symptomatology . to evaluate the formulation of the present invention , the formulation of example 1 was compared with naprosyn in a double - blind double placebo controlled study in osteoarthritic patients . efficacy of both naproxen formulations was indicated by the degree of pain assessed by the patient on a visual analogue scale and was graded on a four point verbal rating scale . in addition , blood samples were analyzed for naproxen plasma concentrations and any adverse effects were recorded . a gastrointestinal tolerability questionnaire was completed by each volunteer at the end of each treatment period . in summary , in terms of clinical efficacy , the naproxen formulation according to the present invention performed as well as the reference and was superior to the reference in terms of fewer gastrointestinal complaints and adverse events , thus demonstrating the safety and advantages of the multiparticulate formulations of the present invention when compared with the commercially available reference products .
a once - daily naproxen formulation for oral administration having a first portion of the naproxen as a multi - particulate pellet form , each pellet having a core of naproxen or a pharmaceutically acceptable salt thereof in association with an organic acid , the core being surrounded by a multi - layer membrane and optionally a second portion of naproxen formulated to release the drug promptly following oral administration .