Methadone, a pharmaceutical opioid, is currently marketed as oral concentrate (10 mg/ml), oral solution (5 and 10 mg/5ml), tablet (5, 10, and 40 mg), injection (10mg/ml) and powder (50, 100, and 500 mg/bottle for prescription compounding).
According to the National Center for Health Statistics
(NCHS) Health E-Stats publication, poisoning deaths increased 66% from 19,741 in 1999 to 32,691 in 2005. During the same time period, methadone deaths increased 469% to 4,460 (14% of all poisonings); however, recently methadone overdose deaths have decreased by 24% to 3,373 in 2016. In November
2006, the Food and Drug Administration (FDA) issued a public health advisory stating that methadone use in pain control may result in life-threatening cardiac and respiratory changes and deaths. FDA further advised that methadone doses for pain relief should be carefully selected, slowly titrated and carefully monitored by the prescribing physician. As of January 1, 2008, manufacturers of 40 mg methadone hydrochloride dispersible tablets have voluntarily agreed to restrict distribution of this formulation to only hospitals and those facilities authorized for detoxification and maintenance treatment of opioid addiction.
The 40 mg methadone product is not FDA approved for use in the management of pain.
Methadone Dosing Recommendations for the Treatment of Chronic Pain
Traditionally methadone has been associated with the treatment of heroin addiction. However, methadone is an analgesic alternative for treating refractory pain. Pharmacokinetic properties of methadone require initiation at a low dosage with gradual titration to effect to reduce the potential for side effects and adverse outcomes. Risk of toxicity due to overdose increases greatly if the dosage is increased too rapidly.
Special pharmacokinetic properties of methadone
• Long elimination half-life (128hrs) coupled with a
• Much shorter duration of analgesic effect (6-8 hours) results in
• Risk of drug accumulation and adverse effects
• Half-life does not predict duration of analgesia
• Analgesic effects may require initial dosing interval of 6 hours.
• Repeated dosing will result in tissue accumulation and may require dosing intervals of 8-12 hours or reduction in dose with chronic utilization.
Benefits of methadone
• Duration of analgesia 6-8 hours or longer
• Effective in pain that is non-responsive or refractory to other opioid analgesic agents because of incomplete cross tolerance
• No active metabolites
• Low cost (long acting morphine is also a lower cost alternative to the more expensive long acting opioid analgesic agents)
Irregular, fast or slow, or shallow breathing
Loss of appetite
Muscle pain or cramps
Nausea or vomiting
Numbness or tingling in the hands, feet, or lips
Pale or blue lips, fingernails, or skin
Pinpoint red spots on the skin
Puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
Swelling of the face, fingers, feet, or lower legs
Unusual bleeding or bruising
Unusual tiredness or weakness
Methadone may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can infrequently result in serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that need medical attention right away.