Methadone

alkaloid · nervous · Oral · IV · Intramuscular

Methadone, an alkaloid. Synthetic μ-opioid agonist + NMDA antagonist + monoamine reuptake inhibition. Long, variable half-life (8–60 h) supports… Oral half-life 37 h.

Synthetic μ-opioid agonist + NMDA antagonist + monoamine reuptake inhibition. Long, variable half-life (8–60 h) supports once-daily dosing for opioid use disorder. QT prolongation requires baseline ECG.

Pharmacokinetics

• Oral — t½ 37 h · F 80% · ka 0.85 h⁻¹ · Vd 280 L
• IV — t½ 37 h · F 100% · Vd 280 L

Sources: PMID:9354306, PMID:7193106, PMID:2311335