A new mathematical approach to methadone conversion

Abstract

For the past 20 years, methadone has been experiencing resurgence in the palliative care community as a second-line opioid for the treatment of cancer pain. Methadone is useful for refractory pain in cancer patients or in those who could not tolerate the side effects of other opioids; its positives are well cited in recent literature including dual elimination without active metabolites, N-methyl-D-aspartate antagonism, mu and delta receptor activity, multiple routes of administration, rapid onset of action, long half-life, low cost, and fewer adverse effects. Despite the abundance of recent case reports and literature reviews demonstrating the effective use of methadone in cancer patients, there is a lack of consensus for an appropriate method for converting morphine (and by extension, other opioids) to methadone.