Methadone assisted treatment of substance use disorders is well known but its potential for perioperative analgesia is under appreciated.
This review (full text for ASA members or subscription) may be helpful to introduce it as a long lasting intravenous agent given at the beginning of surgery. Common doses are 0.1 – 0.3mg/kg or a single 20mg dose with 3 – 5mg in PACU q 20mins. Analgesia is generally quite prolonged for 24 hours or more, and most of the evidence provided here does not show a higher rate of respiratory depression.
Caution is advised in the elderly or morbidly obese or those with cardiovascular co-morbidities. Further studies are needed on its potential adverse effects on QT prolongation or serotonin syndrome, effects on chronic pain, use in ambulatory surgery and in enhanced recovery protocols.