Drug interactions
Lonafarnib + Metronidazole
Severity: Major
Lonafarnib and Metronidazole: 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
Lonafarnib is a sensitive CYP3A4 substrate, and increased exposure raises the risk of toxicity including QT prolongation, gastrointestinal effects and hepatic effects. Combination with CYP3A inhibitors is not recommended in labeling.
What this interaction means in plain words
Lonafarnib and Metronidazole 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.
Lonafarnib belongs to Miscellaneous; Metronidazole belongs to Anti Parasitic.
Why it happens
Metronidazole may inhibit CYP3A4 and reduce lonafarnib clearance, though its inhibitory effect is weak to moderate.
What to do
Prefer a non-interacting antimicrobial; if unavoidable, monitor ECG and for adverse effects and consider lonafarnib dose reduction.
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 Metronidazole
- Ethanol + Metronidazole Contraindicated
- Metronidazole + Pimozide Contraindicated
- Amiodarone + Metronidazole Major
- Disulfiram + Metronidazole Major
- Ergotamine + Metronidazole Major
- Lomitapide + Metronidazole Major
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 Lonafarnib with Metronidazole?
MediHelp rates the interaction as major. Lonafarnib and Metronidazole 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. Lonafarnib is a sensitive CYP3A4 substrate, and increased exposure raises the risk of toxicity including QT prolongation, gastrointestinal effects and hepatic effects. Combination with CYP3A inhibitors is not recommended in labeling.
How serious is the interaction between Lonafarnib and Metronidazole?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Prefer a non-interacting antimicrobial; if unavoidable, monitor ECG and for adverse effects and consider lonafarnib dose reduction.
What other medicines interact with Metronidazole?
MediHelp also lists interactions of Metronidazole with, for example, Ethanol, Pimozide, Amiodarone. The full list is on the Metronidazole page.
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