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Methadone and Rifampin

Desk tier: Serious concern

Mechanism: moderate CYP2B6 induction of clearance (↓ exposure / loss of efficacy)

“The concomitant use of methadone hydrochloride tablets and CYP3A4, CYP2B6, CYP2C19, or CYP2C9 inducers can decrease the plasma concentration of methadone”
Methadone HCl tablets, section 7 DRUG INTERACTIONS (Inducers of CYP3A4, CYP2B6, CYP2C19, or CYP2C9). DailyMed label
Why this grade

Methadone HCl tablets label, 7 DRUG INTERACTIONS (Inducers of CYP3A4, CYP2B6, CYP2C19, or CYP2C9)

The Methadone HCl tablets label warns about this interaction: "The concomitant use of methadone hydrochloride tablets and CYP3A4, CYP2B6, CYP2C19, or CYP2C9 inducers can decrease the plasma concentration of methadone" Retrieved from DailyMed 2026-09-27.

Open source

FDA interaction table

FDA's example-interaction table lists Rifampin as a moderate CYP2B6 inducer. FDA grades the roles; the severity tier on this row is the desk's rule. Table content current as of 2026-05-29.

Open source

PMID 31006110

2019 Clin Pharmacol Ther. 2B6 PM stacks efavirenz. Same isoform as ketamine and methadone.

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Open this pair in the desk

All pairs for Methadone · Rifampin

Enzyme behind this pair: CYP2B6

Educational reference only. Not FDA-cleared. The Prescribing Information governs.

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