Methadone Dosing

Last updated: February 9, 2026

1. Administer 0.1 mg/kg intravenously (IV) for opioid-naive patients (approx. 10 mg) and 0.2 mg/kg IV for opioid-tolerant patients (approx. 20 mg).
2. If administering orally (PO), the IV-to-PO conversion ratio is approximately 1:2.
3. Assess the corrected QT interval (QTc) prior to administration.

Razvan’s Notes

The initial doses of 0.1–0.2 mg/kg are conservative; clinical recommendations often suggest a target of 0.2–0.3 mg/kg. Doses of 20 mg or higher reach a pharmacokinetic threshold where methadone becomes long-acting, providing analgesia for 24 hours or more. If your attending refuses to believe this, please refer them to this review article (see Figure 1).