Drug interactions
Fosamprenavir + Mefloquine
Severity: Major
Fosamprenavir and Mefloquine: major interaction.
Last updated Sources: US FDA label
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
Fosamprenavir, whose active form amprenavir inhibits CYP3A4, especially when boosted with ritonavir, may increase mefloquine exposure. This raises the risk of mefloquine toxicity, including cardiac and neuropsychiatric effects, which may last because of mefloquine's long half-life.
What this interaction means in plain words
Fosamprenavir and Mefloquine 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.
Why it happens
Inhibition of CYP3A4-mediated mefloquine metabolism raises mefloquine concentrations.
What to do
Avoid the combination and use another antimalarial. If unavoidable, monitor the ECG and neuropsychiatric symptoms.
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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References
Other interactions of Mefloquine
- Arsenic trioxide + Mefloquine Contraindicated
- Dronedarone + Mefloquine Contraindicated
- Ibutilide + Mefloquine Contraindicated
- Levoketoconazole + Mefloquine Contraindicated
- Mefloquine + Nilotinib Contraindicated
- Mefloquine + Pimozide Contraindicated
Frequently asked questions
Can I take Fosamprenavir with Mefloquine?
MediHelp rates the interaction as major. Fosamprenavir and Mefloquine 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. Fosamprenavir, whose active form amprenavir inhibits CYP3A4, especially when boosted with ritonavir, may increase mefloquine exposure. This raises the risk of mefloquine toxicity, including cardiac and neuropsychiatric effects, which may last because of mefloquine's long half-life.
How serious is the interaction between Fosamprenavir and Mefloquine?
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 the combination and use another antimalarial. If unavoidable, monitor the ECG and neuropsychiatric symptoms.
What other medicines interact with Mefloquine?
MediHelp also lists interactions of Mefloquine with, for example, Arsenic trioxide, Dronedarone, Ibutilide. The full list is on the Mefloquine page.
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