Drug interactions
Loratadine + Mavacamten
Severity: Moderate
Loratadine 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
Mavacamten is cleared largely by CYP2C19, and its exposure rises when this pathway is inhibited. Higher exposure can excessively reduce left ventricular ejection fraction and cause heart failure from systolic dysfunction. Loratadine is only a weak inhibitor of this pathway in practice, so the clinical effect is probably smaller than for strong inhibitors.
What this interaction means in plain words
Loratadine 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.
Loratadine belongs to Respiratory; Mavacamten belongs to Cardiovascular.
Why it happens
Possible weak inhibition of CYP2C19-mediated mavacamten metabolism raising mavacamten plasma concentrations.
What to do
Monitor LVEF by echocardiography per the mavacamten dosing schedule when loratadine is started or stopped, and reduce the dose or interrupt therapy if ejection fraction falls. Consider a non-interacting antihistamine if concern persists.
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 Loratadine
- Acrivastine + Loratadine Moderate
- Amobarbital + Loratadine Moderate
- Fentanyl + Loratadine Moderate
- Isocarboxazid + Loratadine Moderate
- Levoketoconazole + Loratadine Moderate
- Loratadine + Rifampin Moderate
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 Loratadine with Mavacamten?
MediHelp rates the interaction as moderate. Loratadine 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. Mavacamten is cleared largely by CYP2C19, and its exposure rises when this pathway is inhibited. Higher exposure can excessively reduce left ventricular ejection fraction and cause heart failure from systolic dysfunction. Loratadine is only a weak inhibitor of this pathway in practice, so the clinical effect is probably smaller than for strong inhibitors.
How serious is the interaction between Loratadine 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 LVEF by echocardiography per the mavacamten dosing schedule when loratadine is started or stopped, and reduce the dose or interrupt therapy if ejection fraction falls. Consider a non-interacting antihistamine if concern persists.
What other medicines interact with Loratadine?
MediHelp also lists interactions of Loratadine with, for example, Acrivastine, Amobarbital, Fentanyl. The full list is on the Loratadine page.
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