Drug interactions
Methadone + Pentamidine
Severity: Major
Methadone and Pentamidine: major interaction.
Last updated
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 can prolong the QT interval, and combined use raises the likelihood of torsades de pointes and other serious ventricular arrhythmias. The risk is greater with electrolyte disturbances, higher methadone doses or underlying heart disease.
What this interaction means in plain words
Methadone and Pentamidine 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; Pentamidine belongs to Anti Parasitic.
Why it happens
Additive blockade of cardiac potassium channels (hERG) leading to delayed repolarization and QT prolongation.
What to do
Avoid the combination where possible; if pentamidine is essential, obtain a baseline and follow-up ECG and correct potassium and magnesium. Consider lowering the methadone dose or switching to an opioid with less QT effect.
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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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 Pentamidine
- Clomipramine + Pentamidine Contraindicated
- Desipramine + Pentamidine Contraindicated
- Dronedarone + Pentamidine Contraindicated
- Moxifloxacin + Pentamidine Contraindicated
- Nortriptyline + Pentamidine Contraindicated
- Pentamidine + Pimozide Contraindicated
Frequently asked questions
Can I take Methadone with Pentamidine?
MediHelp rates the interaction as major. Methadone and Pentamidine 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 can prolong the QT interval, and combined use raises the likelihood of torsades de pointes and other serious ventricular arrhythmias. The risk is greater with electrolyte disturbances, higher methadone doses or underlying heart disease.
How serious is the interaction between Methadone and Pentamidine?
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 the combination where possible; if pentamidine is essential, obtain a baseline and follow-up ECG and correct potassium and magnesium. Consider lowering the methadone dose or switching to an opioid with less QT effect.
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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