Drug interactions
Methadone + Posaconazole
Severity: Major
Methadone and Posaconazole: 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
Posaconazole inhibits methadone metabolism and both drugs prolong the QT interval. The combination can lead to methadone accumulation, sedation, respiratory depression and torsades de pointes.
What this interaction means in plain words
Methadone and Posaconazole 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; Posaconazole belongs to Anti Fungals.
Why it happens
CYP3A4 inhibition by posaconazole increases methadone levels, with additive QT prolongation.
What to do
Obtain a baseline ECG and monitor the QTc and electrolytes, and watch for opioid toxicity. Consider reducing the methadone dose or using an alternative antifungal.
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 Posaconazole
- Artemether + Posaconazole Contraindicated
- Avanafil + Posaconazole Contraindicated
- Cobimetinib + Posaconazole Contraindicated
- Conivaptan + Posaconazole Contraindicated
- Dihydroergotamine intranasal + Posaconazole Contraindicated
- Dihydroergotamine + Posaconazole Contraindicated
Frequently asked questions
Can I take Methadone with Posaconazole?
MediHelp rates the interaction as major. Methadone and Posaconazole 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. Posaconazole inhibits methadone metabolism and both drugs prolong the QT interval. The combination can lead to methadone accumulation, sedation, respiratory depression and torsades de pointes.
How serious is the interaction between Methadone and Posaconazole?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Obtain a baseline ECG and monitor the QTc and electrolytes, and watch for opioid toxicity. Consider reducing the methadone dose or using an alternative antifungal.
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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