Claims for Patent: 4,721,619

Summary for Patent: 4,721,619

Title:	Controlled absorption diltiazen pharmaceutical formulation
Abstract:	A controlled absorption diltiazem formulation for oral administration comprises a pellet having a core of diltiazem or a pharmaceutically acceptable salt thereof in association with an organic acid and a lubricant, and an outer membrane which permits release of diltiazem in an aqueous medium at a controlled rate which is substantially pH independent. The pellet has a dissolution rate in vitro, which when measured according to the Paddle Method of U.S. Pharmacopoeia XX, is not more than 10% of the total diltiazem after 2 hours of measurement in a buffered medium. Not more than 30% of the total diltiazem is released after a total of 4 hours measurement and not more than 40% of the total diltiazem is released after a total of 6 hours. 100% release is achieved after 12 hours, with a maximum of 80% of the total diltiazem being released after 8 hours.
Inventor(s):	Panoz; Donald E. (Whale Bay, BM), Geoghegan; Edward J. (Athlone, IE)
Assignee:	Elan Corporation p.l.c. (IE)
Application Number:	06/684,661
Patent Claims:	1. A controlled absorption diltiazem formulation for oral administration, comprising a pellet having a core of diltiazem or a pharmaceutically acceptable salt thereof in association with an organic acid and a lubricant, and a multi-layer membrane surrounding said core and containing a major proportion of a pharmaceutically acceptable film forming, water insoluble polymer and a minor proportion of a pharmaceutically acceptable film forming, water soluble polymer, the number of layers in said membrane and the ratio of said water soluble polymer to water insoluble polymer being effective to permit release of said diltiazem from said pellet at a rate allowing controlled absorption thereof over a twelve hour period following oral administration, said rate being measured in vitro as a dissolution rate of said pellet which is substantially pH independent, which when measured in a basket assembly according to U.S. Pharmacopoeia XX substantially corresponds to the following dissolution pattern: (a) from 0 to 10% of the total diltiazem is released after 2 hours of measurement; (b) from 10 to 30% of the total diltiazem is released after 4 hours of measurement; (c) from 20 to 40% of the total diltiazem is released after 6 hours of measurement; (d) from 50 to 80% of the total diltiazem is released after 8 hours of measurement; and (e) from 85 to 100% of the total diltiazem is released after 12 hours of measurement. 2. A formulation according to claim 1, wherein the organic acid is selected from the group consisting of one or more of the following acids: fumaric acid, malic acid and succinic acid, the diltiazem and organic acid being present in a ratio of from 19:1 to 1:1. 3. A formulation according to claim 2, wherein the lubricant is selected from the group consisting of one or more of sodium stearate, magnesium stearate and talc and the diltiazem and the lubricant are present in a ratio of from 5:1 to 100:1. 4. A formulation according to claim 3, wherein the core comprises: (a) a powder mixture comprising diltiazem or a pharmaceutically acceptable salt thereof, an organic acid selected from the group consisting of fumaric acid, malic acid and succinic acid, and said lubricant, and (b) a polymeric material comprising a major proportion of a pharmaceutically acceptable water soluble polymer and a minor proportion of a pharmaceutically acceptable water insoluble polymer, said core comprising layers of said powder mixture and said polymeric material superimposed one upon the other wherein said polymeric material is present in an amount sufficient to ensure that all of said powder mixture is coated into said core. 5. A formulation according to claim 4, wherein the pharmaceutically acceptable water soluble polymer is selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone and hydroxypropylmethylcellulose. 6. A formulation according to claim 4, wherein the pharmaceutically acceptable water insoluble polymer is selected from the group consisting of polyvinylchloride, shellac, polyurethane and ethylcellulose. 7. A formulation according to claim 1, wherein the water insoluble polymer of the membrane is selected from the group consisting of polyvinylchloride, shellac, polyurethane and ethylcellulose and the water soluble polymer is selected from the group consisting of polyvinyl alcohol, polyvinylpyrrolidone and hydroxypropylmethylcellulose. 8. A formulation according to claim 4, wherein the polymeric material of the core comprises a major proportion of a copolymer of acrylic and methacrylic acid esters which is freely permeable to water and a minor proportion of a copolymer of acrylic and methacrylic acid esters which is slightly permeable to water. 9. A formulation according to claim 1 wherein the multi-layer membrane consists of a major proportion of a copolymer of acrylic and methacrylic acid esters which is slightly permeable to water and a minor proportion of a copolymer of acrylic and methacrylic acid esters which is freely permeable to water. 10. A capsule comprising pellets according to claim 1.