Drug interactions
Granisetron + Methadone
Severity: Major
Granisetron and Methadone: 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
Methadone causes dose-related QT prolongation and torsades de pointes. Granisetron adds a small QT effect, so the risk of serious arrhythmia increases, especially at higher methadone doses or with electrolyte abnormalities.
What this interaction means in plain words
Granisetron and Methadone 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.
Granisetron belongs to Gastrointestinal Tract; Methadone belongs to Musculoskeletal.
Why it happens
Additive QT interval prolongation via cardiac potassium channel effects.
What to do
Obtain a baseline and follow-up ECG and correct electrolytes. Use an alternative antiemetic in patients with a prolonged QTc or on high methadone doses.
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 Granisetron
- Apomorphine + Granisetron Contraindicated
- Amiodarone + Granisetron Major
- Amisulpride + Granisetron Major
- Arsenic trioxide + Granisetron Major
- Artemether / lumefantrine + Granisetron Major
- Artemether + Granisetron Major
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
Frequently asked questions
Can I take Granisetron with Methadone?
MediHelp rates the interaction as major. Granisetron and Methadone 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 causes dose-related QT prolongation and torsades de pointes. Granisetron adds a small QT effect, so the risk of serious arrhythmia increases, especially at higher methadone doses or with electrolyte abnormalities.
How serious is the interaction between Granisetron and Methadone?
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 and follow-up ECG and correct electrolytes. Use an alternative antiemetic in patients with a prolonged QTc or on high methadone doses.
What other medicines interact with Granisetron?
MediHelp also lists interactions of Granisetron with, for example, Apomorphine, Amiodarone, Amisulpride. The full list is on the Granisetron page.
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