Claims for Patent: 5,637,320

Summary for Patent: 5,637,320

Title:	Controlled absorption naproxen formulation for once-daily administration
Abstract:	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.
Inventor(s):	Bourke; Edward A. (Athlone, IE), Mulligan; Seamus (Athlone, IE)
Assignee:	Elan Corporation, PLC (Athlone, IE)
Application Number:	08/227,566
Patent Claims:	1. A naproxen formulation for once-daily oral administration comprising naproxen in 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 naproxen or pharmaceutically acceptable salt thereof and the organic acid being present in a ratio of from 20:1 to 1:1, and a multi-layer membrane surrounding said core and containing a pharmaceutically acceptable film-forming, water insoluble polymer and optionally a pharmaceutically acceptable film-forming, water soluble polymer and having a dissolution rate which when measured in vitro in a type 1 dissolution basket apparatus according to U.S. Pharmacopoeia XXI in phosphate buffer at pH 7.2 and at 75 r.p.m. corresponds to the following dissolution pattern: a) from 0 to 50% of the total naproxen is released after 1 hour of measurement in said apparatus; b) from 20 to 70% of the total naproxen is released after 2 hours of measurement in said apparatus; and c) not less than 50% of the total naproxen is released after a total of 4 hours of measurement in said apparatus. 2. A pellet formulation according to claim 1, wherein the pellet has a dissolution rate which when measured in vitro in a type 2 dissolution paddle apparatus according to U.S. Pharmacopoeia XXII in phosphate buffer at pH 7.4 and at 50 r.p.m. corresponds to the following dissolution pattern: a) from 20 to 70% of the total naproxen is released after 1 hour of measurement in said apparatus; b) not less than 50% of the total naproxen is released after 2 hours of measurement in said apparatus; and c) not less than 75% of the total naproxen is released after a total of 4 hours of measurement in said apparatus. 3. A pellet formulation according to claim 1, wherein the organic acid is selected from the group consisting of adipic acid, ascorbic acid, citric acid, fumaric acid, maleic acid, succinic acid and tartaric acid. 4. A pellet formulation according to claim 1, wherein the naproxen or pharmaceutically acceptable salt thereof and organic acid are present in a ratio of 6:1 to 1:1. 5. A pellet formulation according to claim 1, wherein the core comprises naproxen or a pharmaceutically acceptable salt thereof and the associated organic acid embedded in one or more polymers. 6. A pellet formulation according to claim 5, wherein the one or more polymers are insoluble in water. 7. A pellet formulation according to claim 5, wherein the core comprises: a) a powder mixture containing naproxen or a pharmaceutically acceptable salt thereof, an organic acid selected from adipic acid, ascorbic acid, citric acid, fumaric acid, malic acid, succinic acid and tartaric acid; and b) one or more polymers containing a proportion of a pharmaceutically acceptable water soluble or freely water permeable polymer and a proportion of a pharmaceutically acceptable water insoluble polymer, said core comprising layers of said powder mixture and said one or more polymers superimposed one upon the other and said one or more polymers forming an outer coat of said core. 8. A pellet formulation according to claim 5, wherein the naproxen, organic acid and one or more polymers are built up on a central active core. 9. A pellet formulation according to claim 8, wherein the active core is formed by blending the naproxen, organic acid and one or more polymers to form a homogenous powder, shaping a portion of said blend to form a central core and applying the remainder of said blend alternately or simultaneously with a polymer binding solution to form a layered structure on said central core. 10. A pellet formulation according to claim 5, wherein the naproxen, organic acid and one or more polymers are built up on an inert core. 11. A formulation according to claim 1, which contains naproxen sodium as the active ingredient. 12. A controlled absorption naproxen formulation for oral administration, comprising pellets according to claim 1, said formulation including a rapid release form of naproxen. 13. A controlled absorption naproxen formulation according to claim 12, having a dissolution rate which when measured in a type 1 dissolution basket apparatus according to U.S. Pharmacopoeia XXII in phosphate buffer at pH 7.2 and at 75 r.p.m. corresponds to the following dissolution pattern: a) from 15 to 50% of the total naproxen is released after 0.5 hours of measurement in said apparatus; b) from 25 to 75% of the total naproxen is released after 1 hour of measurement in said apparatus; and c) not less than 65% of the total naproxen is released after 4 hours of measurement in said apparatus. 14. A controlled absorption naproxen formulation according to claim 12, having a dissolution rate which when measured in a type 2 dissolution paddle apparatus according to U.S. Pharmacopoeia XXII in phosphate buffer at pH 7.4 and at 50 r.p.m. corresponds to the following dissolution pattern: a) from 25 to 60% of the total naproxen is released after 0.5 hours of measurement in said apparatus; b) from 35 to 75% of the total naproxen is released after 1 hour of measurement in said apparatus; c) not less than 65% of the total naproxen is released after 4 hours of measurement in said apparatus. 15. A controlled absorption naproxen formulation according to claim 12, which comprises a blend of pellets, together with up to 60% by weight of a rapid release form of naproxen. 16. A capsule or tablet comprising a formulation according to claim 1. 17. A capsule or tablet comprising a formulation according to claim 12.