Drug interactions
Letrozole + Mavacamten
Severity: Moderate
Letrozole and Mavacamten: moderate 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
Letrozole may inhibit CYP2C19 to a modest degree and could raise mavacamten exposure. Mavacamten has a narrow therapeutic window, and higher exposure can reduce left ventricular ejection fraction and cause heart failure.
What this interaction means in plain words
Letrozole and Mavacamten can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Letrozole belongs to Oncology; Mavacamten belongs to Cardiovascular.
Why it happens
Inhibition of CYP2C19-mediated mavacamten metabolism by letrozole, which reduces clearance.
What to do
Monitor echocardiographic LVEF and clinical status when letrozole is started or stopped during mavacamten therapy. Adjust the mavacamten dose per labeling if LVEF falls or symptoms of heart failure appear.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Letrozole
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 Letrozole with Mavacamten?
MediHelp rates the interaction as moderate. Letrozole and Mavacamten can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Letrozole may inhibit CYP2C19 to a modest degree and could raise mavacamten exposure. Mavacamten has a narrow therapeutic window, and higher exposure can reduce left ventricular ejection fraction and cause heart failure.
How serious is the interaction between Letrozole and Mavacamten?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor echocardiographic LVEF and clinical status when letrozole is started or stopped during mavacamten therapy. Adjust the mavacamten dose per labeling if LVEF falls or symptoms of heart failure appear.
What other medicines interact with Letrozole?
MediHelp also lists interactions of Letrozole with, for example, Desogestrel-ethinyl estradiol, Ethinyl estradiol-drospirenone, Ethinyl estradiol-levonorgestrel. The full list is on the Letrozole page.
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