Methadone for persistent pain in the older patient

Abstract

Methadone is a synthetic opioid analgesic developed almost 60 years ago in response to a shortage of supplies of traditional opioids caused by the Second World War. Until a few years ago, this agent saw relatively little use other than as a maintenance therapy in narcotic addicts. A lack of knowledge regarding the unusual pharmacokinetics and pharmacodynamics of the drug and their impact on its clinical use invited therapeutic misadventures, which manifested as delayed severe toxicity. With the discovery and dissemination of the pharmacokinetic and pharmacodynamic behaviors and nonopioid mechanisms of action of methadone over the past 10–15 years, support for the use of methadone as a first-line opioid analgesic has been slowly progressing. Risk factors for excessive methadone accumulation have been identified, as have several dosing methodologies that allow its safe use, even in the oldest individuals. Methadone is no longer a medication only to be used by specialists in pain clinics. However, it should be used only by clinicians who are experienced in the use and monitoring of opioids, especially when moderate or high doses are required. This review summarizes the information necessary to allow its safe and effective use in the elderly population.