Opioid switch to oral methadone in cancer pain

The occurrence of undesirable side effects due to opioids (delirium, confus ion, myoclonus, nausea, emesis) is one of the major complications in the ma nagement of pain, especially in chronic cancer pain states. Methadone, as a n alternative to morphine, has been proposed in the control of opioid-induc ed toxicity. Methadone is a synthetic opioid, with mu and delta receptor ac tivity, associated with the capacity to inhibit N-methyl-D-aspartate recept ors. Questions have arisen concerning its equianalgesic ratio since its red iscovery over the past few years and are certainly related to its receptor interactions. Aspects of its pharmacology, indications, and switching modal ities are discussed here. Opioid rotation is a new tool in the management of cancer pain, deserving m ore attention. Curr Opin Oncol 2000, 12:308-313 (C) 2000 Lippincott William s & Wilkins. Inc.