Clinical pharmacology of methadone for pain

Abstract

In spite of challenges related to the variable pharmacokinetics and concerns regarding increase in QTc time, current evidence indicates that opioid switching to methadone improves pain control in a substantial proportion of patients who are candidates for opioid switching. Measures must be instituted to secure that patients receiving methadone for pain are not considered opioid addicts.

Methadone Deaths: Risk Factors in Pain and Addicted Populations

“…Methadone is seldom employed as a first-line analgesic, 39 and transitioning from another opioid analgesic to methadone can be fraught with difficulties. The "3-day" and "stop-and-go" approaches are two commonly employed strategies.…”

“…38 Further, pain patients receive multiple methadone doses each day, with average total daily doses generally higher than those used in MMT. 32,39 Although MMT clinics require that patients demonstrate the ability to use methadone responsibly before take-home privileges are granted, 8 pain patients tend to self-administer methadone at the outset of treatment. This less stringent methadone monitoring combined with the complexities of dosing regimens may increase iatrogenic risks.…”

“…end of life) in which benefits of improving refractory pain may outweigh risks associated with methadone. 39 Elderly, medically compromised, and opioid-naïve individuals starting on methadone require special dosing considerations. According to Canadian guidelines, 32 initial methadone doses for opioid-naïve patients should not exceed 15-30 mg a day for the first three days, and it may be as low as 1-2 mg in medically vulnerable patients.…”

“…Several guidelines recommend a 75-95% reduction from the calculated methadone dose (and no more than 40 mg) as the initial dose, short-acting opioids for breakthrough pain, and close monitoring to ensure adequate analgesia and minimal side effects. 32,38,39 To avoid fatalities, the family should be cognizant of, and alert to, sedation and respiratory depression.…”

“…The "3-day" and "stop-and-go" approaches are two commonly employed strategies. 39 In the "3-day" method, the dose of the first opioid is reduced over 3 days (one-third reduction daily) and replaced with the equianalgesic dose of methadone. Using the "stop-and-go" method, the initial opioid is discontinued and immediately substituted with an equianalgesic dose of methadone.…”