Claims for Patent: 5,508,276

Summary for Patent: 5,508,276

Title:	Duloxetine enteric pellets
Abstract:	A superior enteric formulation of the antidepressant drug, duloxetine, is in the form of enteric pellets of which the enteric layer comprises hydroxypropylmethylcellulose acetate succinate.
Inventor(s):	Anderson; Neil R. (West Lafayette, IN), Oren; Peter L. (Fishers, IN), Ogura; Toshihiro (Osaka, JP), Fujii; Toshiro (Hyogo, JP)
Assignee:	Eli Lilly and Company (Indianapolis, IN) Shionogi & Co. (Osaka, JP)
Application Number:	08/276,232
Patent Claims:	1. An enteric duloxetine pellet comprising a) a core consisting of duloxetine and a pharmaceutically acceptable excipient; b) an optional separating layer; c) an enteric layer comprising hydroxypropylmethylcellulose acetate succinate (HPMCAS) and a pharmaceutically acceptable excipient; d) an optional finishing layer. 2. A pellet of claim 1 wherein the HPMCAS is partially neutralized with ammonium ions to the degree that from about 0% to about 25% of the succinic acid groups are neutralized. 3. A pellet of claim 2 wherein the HPMCAS is partially neutralized to the degree that from about 0% to about 15% of the succinic acid groups are neutralized. 4. A pellet of claim 1 wherein the separating layer is present. 5. A pellet of claim 1 wherein the average particle size of the duloxetine is about 50 .mu.m or less. 6. A pellet of claim 5 wherein the core comprises an inert bead on which the duloxetine is deposited as a layer comprising in addition a pharmaceutically acceptable excipient. 7. A pellet of claim 6 wherein the separating layer is present. 8. A pellet of claim 7 wherein the HPMCAS is partially neutralized with ammonium ions to the degree that from about 0% to about 25% of the succinic acid groups are neutralized. 9. A pellet of claim 4 wherein the separating layer comprises a pharmaceutically acceptable sugar. 10. A pellet of claim 9 wherein the sugar is sucrose. 11. A process for preparing an enteric duloxetine pellet comprising a) providing a core consisting of duloxetine and a pharmaceutically acceptable excipient; b) optionally, applying to the core a separating layer comprising a pharmaceutically acceptable excipient; c) applying an enteric layer comprising HPMCAS and a pharmaceutically acceptable excipient, wherein the HPMCAS is supplied as an aqueous solution or suspension and the application takes place in an apparatus of the fluid bed type; d) optionally, applying a finishing layer. 12. A process of claim 11 wherein the HPMCAS is fully or partially neutralized with ammonium ions. 13. A process of claim 12 wherein the HPMCAS is neutralized to the degree that from about 25% to about 100% of the succinic acid groups are neutralized. 14. A process of claim 11 wherein the separating layer is applied. 15. A process of claim 14 wherein the separating layer comprises a pharmaceutically acceptable sugar. 16. A process of claim 15 wherein the sugar is sucrose. 17. A process of claim 11 wherein the core is prepared by applying duloxetine and a pharmaceutically acceptable excipient to an inert bead. 18. A process of claim 17 wherein the separating layer is applied and comprises a pharmaceutically acceptable sugar.