Drug interactions
Cimetidine + Mavacamten
Severity: Major
Cimetidine and Mavacamten: 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
Mavacamten is cleared largely by CYP2C19, and cimetidine can inhibit this enzyme. Higher mavacamten exposure may reduce left ventricular ejection fraction and risk heart failure.
What this interaction means in plain words
Cimetidine and Mavacamten 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.
Cimetidine belongs to Gastrointestinal Tract; Mavacamten belongs to Cardiovascular.
Why it happens
Inhibition of CYP2C19 (and CYP3A4) by cimetidine decreases mavacamten clearance.
What to do
Avoid starting cimetidine without echocardiographic follow-up, and monitor LVEF and Valsalva gradient with mavacamten dose adjustment per labeling when cimetidine is started or stopped.
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 Cimetidine
- Cimetidine + Dofetilide Contraindicated
- Cimetidine + Fezolinetant Contraindicated
- Alfentanil + Cimetidine Major
- Atazanavir + Cimetidine Major
- Carmustine + Cimetidine Major
- Cimetidine + Citalopram Major
Other interactions of Mavacamten
- Apalutamide + Mavacamten Contraindicated
- Carbamazepine + Mavacamten Contraindicated
- Clarithromycin + Mavacamten Contraindicated
- Dexlansoprazole + Mavacamten Contraindicated
- Efavirenz + Mavacamten Contraindicated
- Enzalutamide + Mavacamten Contraindicated
Frequently asked questions
Can I take Cimetidine with Mavacamten?
MediHelp rates the interaction as major. Cimetidine and Mavacamten 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. Mavacamten is cleared largely by CYP2C19, and cimetidine can inhibit this enzyme. Higher mavacamten exposure may reduce left ventricular ejection fraction and risk heart failure.
How serious is the interaction between Cimetidine and Mavacamten?
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 starting cimetidine without echocardiographic follow-up, and monitor LVEF and Valsalva gradient with mavacamten dose adjustment per labeling when cimetidine is started or stopped.
What other medicines interact with Cimetidine?
MediHelp also lists interactions of Cimetidine with, for example, Dofetilide, Fezolinetant, Alfentanil. The full list is on the Cimetidine page.
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