Drug interactions
Diltiazem + Saquinavir
Severity: Major
Diltiazem and Saquinavir: 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
Diltiazem can raise saquinavir levels and saquinavir (usually ritonavir-boosted) can raise diltiazem levels, with additive risk of PR and QT prolongation, bradycardia and hypotension.
What this interaction means in plain words
Diltiazem and Saquinavir 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
Mutual inhibition of CYP3A4 metabolism, with additive effects on cardiac conduction.
What to do
Obtain a baseline ECG and monitor PR/QT intervals, heart rate and blood pressure. Reduce the diltiazem dose or choose an alternative if conduction abnormalities develop.
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 Diltiazem
- Diltiazem + Flibanserin Contraindicated
- Diltiazem + Ivabradine Contraindicated
- Diltiazem + Lomitapide Contraindicated
- Diltiazem + Lonafarnib Contraindicated
- Acebutolol + Diltiazem Major
- Alfentanil + Diltiazem Major
Frequently asked questions
Can I take Diltiazem with Saquinavir?
MediHelp rates the interaction as major. Diltiazem and Saquinavir 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. Diltiazem can raise saquinavir levels and saquinavir (usually ritonavir-boosted) can raise diltiazem levels, with additive risk of PR and QT prolongation, bradycardia and hypotension.
How serious is the interaction between Diltiazem and Saquinavir?
MediHelp rates it major, 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 PR/QT intervals, heart rate and blood pressure. Reduce the diltiazem dose or choose an alternative if conduction abnormalities develop.
What other medicines interact with Diltiazem?
MediHelp also lists interactions of Diltiazem with, for example, Flibanserin, Ivabradine, Lomitapide. The full list is on the Diltiazem page.
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