In certain embodiments, the present invention is directed to 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 inner 50% of the dosage form contains at least 80% of the hydrocodone or salt thereof； 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.
