The rediscovery of methadone for cancer pain management.

Methadone is a potent synthetic opioid analgesic best known in Australia as maintenance therapy for narcotic addicts. Acceptance of methadone in cancer pain management is limited by a poor understanding of its pharmacokinetics and confusion about dosage. Many opioid conversion charts underestimate the potency of methadone, resulting in the risk of toxicity. Methadone is a valuable addition to the armamentarium of clinicians treating severe cancer pain, particularly neuropathic pain, that is poorly responsive to opioids or where opioid side effects are unacceptable.