Drug interactions
Cimetidine + Saquinavir
Severity: Moderate
Cimetidine and Saquinavir: 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
Cimetidine raised saquinavir exposure modestly in pharmacokinetic studies, via CYP3A4 inhibition and possibly increased gastric pH. Saquinavir prolongs QT and PR intervals, so higher exposure is relevant.
What this interaction means in plain words
Cimetidine and Saquinavir 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
Cimetidine inhibits CYP3A4 metabolism of saquinavir.
What to do
Obtain a baseline ECG and monitor for QT prolongation; consider famotidine if acid suppression is needed.
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 Cimetidine
- Cimetidine + Dofetilide Contraindicated
- Cimetidine + Fezolinetant Contraindicated
- Alfentanil + Cimetidine Major
- Atazanavir + Cimetidine Major
- Carmustine + Cimetidine Major
- Cimetidine + Citalopram Major
Frequently asked questions
Can I take Cimetidine with Saquinavir?
MediHelp rates the interaction as moderate. Cimetidine and Saquinavir 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. Cimetidine raised saquinavir exposure modestly in pharmacokinetic studies, via CYP3A4 inhibition and possibly increased gastric pH. Saquinavir prolongs QT and PR intervals, so higher exposure is relevant.
How serious is the interaction between Cimetidine and Saquinavir?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Obtain a baseline ECG and monitor for QT prolongation; consider famotidine if acid suppression is needed.
What other medicines interact with Cimetidine?
MediHelp also lists interactions of Cimetidine with, for example, Dofetilide, Fezolinetant, Alfentanil. The full list is on the Cimetidine page.
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