Review of the role of opioids in cancer pain.

Cancer pain is unfortunately very prevalent, with opioids the mainstay of treatment. Knowledge of the types of pain caused by cancer and the effects of various opioids would be expected to improve pain therapy. This article addresses the use, side effects, formulations, and metabolism of the most commonly used opioids in cancer pain management, including morphine, codeine, hydrocodone, hydromorphone, fentanyl, and methadone. The role of opioid conversion and equipotent dosing when changing from one opioid to another is also described.