Disclosed is a solid controlled release dosage form comprising: a therapeutically effective amount of hydrocodone or a pharmaceutically acceptable salt thereof dispersed in a controlled release excipient； wherein the controlled release excipient comprises a material selected from the group consisting of polyethylene oxide, alkylcelluloses, acrylic and methacrylic acid polymers and copolymers, cellulose ethers, carboxyalkylcelluloses, waxes, and mixtures thereof； wherein the dosage form comprises an inner core and a shell encasing the core, wherein the weight ratio of the core to the shell is from about 1:0.5 to about 1:2； wherein the core comprises a first portion of the hydrocodone or pharmaceutically acceptable salt thereof dispersed in a first controlled release excipient, and the shell comprises a second portion of the hydrocodone or pharmaceutically acceptable salt thereof dispersed in a second controlled release excipient； wherein the inner 50 weight-% of the dosage form contains at least 80% of the hydrocodone or salt thereof； and wherein the amount of hydrocodone or salt thereof released from the dosage form is proportional within 20% to elapsed time from 8 to 24 hours, as measured by an in-vitro dissolution in a USP Apparatus 1 (basket) at 100 rpm in 900 ml simulated gastric fluid without enzymes (SGF) at 37°C.
