Drug interactions
Clemastine + Lonafarnib
Severity: Moderate
Clemastine and Lonafarnib: 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
Lonafarnib is a sensitive CYP3A substrate, and CYP3A inhibitors can raise its exposure, increasing adverse effects such as gastrointestinal toxicity and possible QT effects. Clemastine is not a well-established CYP3A inhibitor, so the interaction is largely predicted.
What this interaction means in plain words
Clemastine and Lonafarnib 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.
Clemastine belongs to Respiratory; Lonafarnib belongs to Miscellaneous.
Why it happens
Possible weak CYP3A inhibition by clemastine reducing lonafarnib metabolism; not firmly established.
What to do
Consider an alternative antihistamine that does not inhibit CYP3A. If used, monitor for lonafarnib adverse effects and palpitations or syncope.
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 Clemastine
Other interactions of Lonafarnib
- Alfuzosin + Lonafarnib Contraindicated
- Amobarbital + Lonafarnib Contraindicated
- Apalutamide + Lonafarnib Contraindicated
- Bosentan + Lonafarnib Contraindicated
- Carbamazepine + Lonafarnib Contraindicated
- Clarithromycin + Lonafarnib Contraindicated
Frequently asked questions
Can I take Clemastine with Lonafarnib?
MediHelp rates the interaction as moderate. Clemastine and Lonafarnib 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. Lonafarnib is a sensitive CYP3A substrate, and CYP3A inhibitors can raise its exposure, increasing adverse effects such as gastrointestinal toxicity and possible QT effects. Clemastine is not a well-established CYP3A inhibitor, so the interaction is largely predicted.
How serious is the interaction between Clemastine and Lonafarnib?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Consider an alternative antihistamine that does not inhibit CYP3A. If used, monitor for lonafarnib adverse effects and palpitations or syncope.
What other medicines interact with Clemastine?
MediHelp also lists interactions of Clemastine with, for example, Alfentanil, Benzhydrocodone / acetaminophen, Buprenorphine buccal. The full list is on the Clemastine page.
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