The invention provides a combination dosage form of the peripheral mu opioid antagonist axelopran or a pharmaceutically acceptable salt thereof in an immediate release form and an opioid analgesic agent which may be in an extended release, sustained release, modified release, or controlled release form and methods of preparing such a combination dosage form.本發明提供一種即時釋放型之外週mu類鴉片拮抗劑阿西洛侖(axelopran)或其醫藥可接受之鹽與可緩釋釋放、持續釋放、調節釋放、或控制釋放型之類鴉片鎮痛劑之組合劑型,及製備此組合劑型之方法。