Drug interactions
Methadone + Quinidine
Severity: Major
Methadone and Quinidine: major interaction.
Last updated Sources: US FDA label
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Both drugs prolong the QTc interval, and quinidine is a strong CYP2D6 inhibitor that can raise methadone exposure. The combination carries a high risk of torsades de pointes.
What this interaction means in plain words
Methadone and Quinidine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Methadone belongs to Musculoskeletal; Quinidine belongs to Anti Parasitic.
Why it happens
Additive QT prolongation, plus CYP2D6 inhibition of methadone metabolism.
What to do
Avoid if possible and choose another antiarrhythmic. If used, monitor the ECG and electrolytes and watch for opioid excess.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Methadone
- Alvimopan + Methadone Contraindicated
- Calcium / magnesium / potassium / sodium oxybates + Methadone Contraindicated
- Droperidol + Methadone Contraindicated
- Ibutilide + Methadone Contraindicated
- Isocarboxazid + Methadone Contraindicated
- Lefamulin + Methadone Contraindicated
Other interactions of Quinidine
- Adagrasib + Quinidine Contraindicated
- Arsenic trioxide + Quinidine Contraindicated
- Artemether / lumefantrine + Quinidine Contraindicated
- Chloroquine + Quinidine Contraindicated
- Dofetilide + Quinidine Contraindicated
- Dronedarone + Quinidine Contraindicated
Frequently asked questions
Can I take Methadone with Quinidine?
MediHelp rates the interaction as major. Methadone and Quinidine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Both drugs prolong the QTc interval, and quinidine is a strong CYP2D6 inhibitor that can raise methadone exposure. The combination carries a high risk of torsades de pointes.
How serious is the interaction between Methadone and Quinidine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid if possible and choose another antiarrhythmic. If used, monitor the ECG and electrolytes and watch for opioid excess.
What other medicines interact with Methadone?
MediHelp also lists interactions of Methadone with, for example, Alvimopan, Calcium / magnesium / potassium / sodium oxybates, Droperidol. The full list is on the Methadone page.
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