In certain embodiments, the present invention is directed to a solid controlled release dosage form comprising: a core comprising a first portion of an opioid analgesic dispersed in a first matrix material； and a shell encasing the core and comprising a second portion of the opioid analgesic dispersed in a second matrix material； wherein the amount of opioid analgesic 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.
