Drug interactions
Ketoconazole + Saquinavir
Severity: Major
Ketoconazole and Saquinavir: 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
Ketoconazole increases saquinavir exposure, and both drugs prolong QT and PR intervals, raising the risk of arrhythmia. Saquinavir may also modestly raise ketoconazole levels.
What this interaction means in plain words
Ketoconazole 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
Inhibition of CYP3A4 metabolism of saquinavir, with additive QT/PR effects.
What to do
Use only with ritonavir-boosted saquinavir under ECG monitoring, baseline and follow-up; avoid ketoconazole doses above 200 mg daily with ritonavir-boosted regimens.
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 Ketoconazole
- Alfuzosin + Ketoconazole Contraindicated
- Alprazolam + Ketoconazole Contraindicated
- Avanafil + Ketoconazole Contraindicated
- Conivaptan + Ketoconazole Contraindicated
- Dihydroergotamine intranasal + Ketoconazole Contraindicated
- Dihydroergotamine + Ketoconazole Contraindicated
Frequently asked questions
Can I take Ketoconazole with Saquinavir?
MediHelp rates the interaction as major. Ketoconazole 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. Ketoconazole increases saquinavir exposure, and both drugs prolong QT and PR intervals, raising the risk of arrhythmia. Saquinavir may also modestly raise ketoconazole levels.
How serious is the interaction between Ketoconazole 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: Use only with ritonavir-boosted saquinavir under ECG monitoring, baseline and follow-up; avoid ketoconazole doses above 200 mg daily with ritonavir-boosted regimens.
What other medicines interact with Ketoconazole?
MediHelp also lists interactions of Ketoconazole with, for example, Alfuzosin, Alprazolam, Avanafil. The full list is on the Ketoconazole page.
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