Drug interactions
Saquinavir + Verapamil
Severity: Major
Saquinavir and Verapamil: 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
Saquinavir, boosted with ritonavir, inhibits CYP3A4 and can raise verapamil concentrations substantially. This increases the risk of bradycardia, AV block and hypotension, and saquinavir itself prolongs the QT and PR intervals.
What this interaction means in plain words
Saquinavir and Verapamil 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
Saquinavir/ritonavir inhibit CYP3A4-mediated metabolism of verapamil, with additive effects on cardiac conduction.
What to do
Avoid combining the two where possible. If it is necessary, start verapamil at a reduced dose, monitor ECG, heart rate and blood pressure, and titrate carefully.
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 Verapamil
- Dofetilide + Verapamil Contraindicated
- Flibanserin + Verapamil Contraindicated
- Lomitapide + Verapamil Contraindicated
- Lonafarnib + Verapamil Contraindicated
- Pimozide + Verapamil Contraindicated
- Acebutolol + Verapamil Major
Frequently asked questions
Can I take Saquinavir with Verapamil?
MediHelp rates the interaction as major. Saquinavir and Verapamil 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. Saquinavir, boosted with ritonavir, inhibits CYP3A4 and can raise verapamil concentrations substantially. This increases the risk of bradycardia, AV block and hypotension, and saquinavir itself prolongs the QT and PR intervals.
How serious is the interaction between Saquinavir and Verapamil?
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 combining the two where possible. If it is necessary, start verapamil at a reduced dose, monitor ECG, heart rate and blood pressure, and titrate carefully.
What other medicines interact with Verapamil?
MediHelp also lists interactions of Verapamil with, for example, Dofetilide, Flibanserin, Lomitapide. The full list is on the Verapamil page.
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