Described is a pellet composition comprising a core element comprising morphine sulfate, a filler and a binder, wherein the morphine sulfate, calculated as the anhydrous form, comprises about 50 wt % to about 85 wt % of the total weight of the core element and a coating disposed on at least a portion of the core element, the coating comprising an insoluble matrix polymer which is insoluble at pH 1 to 7.5 an enteric polymer which is insoluble at pH 1 to 4 and soluble at pH 6 to 7.5 and an acid soluble polymer which is soluble at a pH of 1 to 4, wherein the ratio of the acid soluble polymer to the enteric polymer is 1.45:1 to 2.5:1 on a weight basis. Also described are dosage forms comprising the disclosed pellets.
