Drug interactions
Famotidine + Fosamprenavir
Severity: Moderate
Famotidine and Fosamprenavir: 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
Famotidine raises gastric pH, which can lower amprenavir absorption from fosamprenavir. In unboosted regimens this may reduce antiviral exposure and risk virologic failure.
What this interaction means in plain words
Famotidine and Fosamprenavir 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.
Why it happens
Higher gastric pH decreases absorption of amprenavir, the active metabolite of fosamprenavir.
What to do
Give fosamprenavir at least 2 hours before the H2 blocker, and consult the labeling for dose limits when ritonavir is used. Monitor HIV viral load.
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 Famotidine
Frequently asked questions
Can I take Famotidine with Fosamprenavir?
MediHelp rates the interaction as moderate. Famotidine and Fosamprenavir 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. Famotidine raises gastric pH, which can lower amprenavir absorption from fosamprenavir. In unboosted regimens this may reduce antiviral exposure and risk virologic failure.
How serious is the interaction between Famotidine and Fosamprenavir?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Give fosamprenavir at least 2 hours before the H2 blocker, and consult the labeling for dose limits when ritonavir is used. Monitor HIV viral load.
What other medicines interact with Famotidine?
MediHelp also lists interactions of Famotidine with, for example, Atazanavir, Dasatinib, Infigratinib. The full list is on the Famotidine page.
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