Patent ID: 8808745

Claim:
A pharmaceutical composition for controlled release of an opioid into an aqueous medium by erosion of at least one surface of the composition, the composition consisting of: a matrix composition consisting of: (a) one or more polyglycol homopolymers having an average molecular weight of from at least about 100,000 daltons to about 700,000 daltons, (b) a block copolymer of ethylene oxide and propylene oxide having up to about 30% w/w of the propylene oxide based block, based on the total weight of the block copolymer, wherein the block copolymer has an average molecular weight of from about 5,000 to about 15,000 daltons, (c) an opioid, (d) one or more pharmaceutically acceptable excipients selected from the group consisting of cellulose derivatives, release modifiers, and antioxidants, the matrix having a coating having at least one opening exposing at least one surface of said matrix, the coating being insoluble in and impermeable to body fluids, wherein any matrix surface exposed to the aqueous medium erodes at a substantially constant rate, so that a zero order release is obtained of at least about 60% w/w of the opiod from the pharmaceutical composition when subject to an in vitro dissolution test according to USP 24, NF 19, 711 Dissolution, employing Apparatus 2 equipped with a paddle, using 0.1 N hydrochloric acid as the dissolution medium during the first 120 minutes and thereafter substituting a pH 6.8 buffer solution.