Methods of treatment using a gastric retained gabapentin dosage

1. A method for treating neuropathic pain comprising,

administering an extended release oral drug dosage form for releasing gabapentin, comprising,

a core comprising at least 800 mg of gabapentin, and

a semipermeable membrane surrounding the core, the semipermeable membrane comprising a plasticizer and being permeable to a fluid in an environment of use and substantially impermeable to unsolubilized gabapentin,

wherein the dosage form as formulated is of sufficient size for retention in the stomach in a fed mode for a period of at least about 5 hours, and wherein at least about 80 wt % of the gabapentin is released from the dosage form in about 5-12 hours via controlled release through the semipermeable membrane.

2. The method according to claim 1 , wherein the core comprises between about 800-1600 mg gabapentin.

3. The method according to claim 1 , wherein the semipermeable membrane comprises a material selected from the group consisting of acetaldehyde dimethyl acetate, acetaldehyde dimethylcellulose acetate, agar acetate, alkylene oxide and alkyl glycidyl ether copolymers, amylose triacetate, beta glucan acetate, beta glucan triacetate, cellulose esters, cellulose ethers, cellulose ester-ether polymers, mono-, di- and tricellulose acrylates, mono-, di- and tricellulose alkenylates, hydroxylated ethylene-vinyl acetate, polyamides, polyalkylene oxides, polyether and polyamide copolymers, polyglycolic acid, polylactic acid, poly(methacrylate) copolymer salts, cross-linked poly(sodium styrene sulfonate), crosslinked polystyrenes, polyurethanes, polyvinyl alcohol, crosslinked poly(vinylbenzyltrimethyl ammonium chloride), polyvinyl chloride, poly(vinylmethyl ether) copolymers, polyvinylpyrrolidone, propylcarbamate, sulfonated polystyrenes, and triacetate of locust gum bean.

4. The method according to claim 1 , wherein the semipermeable membrane comprises a material selected from the group consisting of cellulose esters, cellulose ethers, polyalkylene oxides, polyvinyl alcohol, and polyvinylpyrrolidone.

5. The method according to claim 4 , wherein the cellulose ester is selected from the group consisting of mono-, di- and tricellulose acetates, cellulose acetate butyl sulfonate, cellulose acetate butyrate, cellulose acetate chloroacetate, cellulose acetate dimethylaminoacetate, cellulose acetate ethyl carbamate, cellulose acetate ethyl carbonate, cellulose acetate ethyl oxalate, cellulose acetate laurate, cellulose acetate methyl carbamate, cellulose acetate methyl sulfonate, cellulose acetate octate, cellulose acetate phthalate, cellulose acetate propionate, cellulose acetate succinate, cellulose acetate p-toluene sulfonate, cellulose acetate valerate, cellulose propionate, cellulose propionate succinate, dimethyl cellulose acetate, mono-, di- and tricellulose acrylates, mono-, di- and tricellulose alkanylates, mono, di and tricellulose aroylates, cellulose triacylates, and cellulose diacylates.

6. The method according to claim 4 , wherein the cellulose ether is selected from the group consisting of ethyl cellulose, hydroxyethylcellulose, hydroxypropylcellulose, and methylcellulose.

7. The method according to claim 1 , wherein the plasticizer is selected from the group consisting of acetylated monoglycerides, dibutyl phthalate, diethyl phthalate, isopropyl phthalate, dimethyl phthalate, dactyl phthalate, dibutyl sebacate, dimethyl sebacate, esters, fatty acids, glycols, oils, glycerin, glycerol, glycerol monostearate, and triacetin.

8. The method according to claim 7 , wherein the plasticizer is selected from esters and fatty acids.

9. The method according to claim 8 , wherein the ester is selected from the group consisting of acetyl triethyl citrate, acetyl tributyl citrate, citrate ester, dibutyl sebacate, tetraethyl acetate, and triethyl citrate.

10. The method according to claim 8 , wherein the fatty acid is stearic acid.

11. The method according to claim 1 , wherein the semipermeable membrane comprises ethyl cellulose, stearic acid, and polyvinylpyrrolidone.

12. The method according to claim 1 , wherein the semipermeable membrane comprises ethyl cellulose, stearic acid, and hydroxypropylcellulose.

13. The method according to claim 3 , wherein the semipermeable membrane comprises polyvinyl alcohol.

14. The method according to claim 13 , wherein the polyvinyl alcohol is a blend of a water soluble polyvinyl alcohol and a water insoluble polyvinyl alcohol.

15. The method according to claim 13 , wherein the polyvinyl alcohol is crosslinked.

16. The method according to claim 1 , wherein the dosage form allows for the extended release of gabapentin in the stomach and small intestine of a mammal.

17. The method according to claim 1 , wherein at least 40 wt % of the gabapentin is retained in the dosage form after 1 hour.

18. A method for treating neuropathic pain, comprising administering an extended release oral drug dosage form for releasing gabapentin into the stomach, duodenum and small intestine of a mammal, comprising,

a core comprising at least 800 mg of gabapentin, and

a semipermeable membrane surrounding the core, the semipermeable membrane comprising a plasticizer and being permeable to a fluid in an environment of use and substantially impermeable to unsolubilized gabapentin,

wherein the dosage form as formulated is of sufficient size for retention in the stomach in a fed mode for a period of at least about 5 hours, and wherein at least about 80 wt % of the gabapentin is released from the dosage form in about 5-12 hours via controlled release through the semipermeable membrane.

19. The method according to claim 3 , wherein the poly(methacrylate) copolymer salt is selected from the group consisting of poly(ammonium methacrylate) copolymer, poly(aminoalkyl methacrylate) copolymer, and (ethyl acrylate)-(methyl methacrylate)-[(trimethylammonium)-ethyl methylacrylate] (1:2:0.2) copolymer.