Drug interactions
Ondansetron + Saquinavir
Severity: Major
Ondansetron 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
Saquinavir prolongs the QT and PR intervals, and ondansetron also prolongs QT. Saquinavir may also raise ondansetron exposure through CYP3A4 inhibition, compounding the risk of torsades de pointes.
What this interaction means in plain words
Ondansetron 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
Additive QT prolongation plus CYP3A4 inhibition by ritonavir-boosted saquinavir that may increase ondansetron levels.
What to do
Avoid the combination where possible and choose an alternative antiemetic. If used, obtain an ECG before and during therapy and keep electrolytes normal.
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 Ondansetron
- Apomorphine + Ondansetron Contraindicated
- Ondansetron + Thioridazine Contraindicated
- Ondansetron + Vandetanib Contraindicated
- Adagrasib + Ondansetron Major
- Amiodarone + Ondansetron Major
- Amisulpride + Ondansetron Major
Frequently asked questions
Can I take Ondansetron with Saquinavir?
MediHelp rates the interaction as major. Ondansetron 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. Saquinavir prolongs the QT and PR intervals, and ondansetron also prolongs QT. Saquinavir may also raise ondansetron exposure through CYP3A4 inhibition, compounding the risk of torsades de pointes.
How serious is the interaction between Ondansetron 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: Avoid the combination where possible and choose an alternative antiemetic. If used, obtain an ECG before and during therapy and keep electrolytes normal.
What other medicines interact with Ondansetron?
MediHelp also lists interactions of Ondansetron with, for example, Apomorphine, Thioridazine, Vandetanib. The full list is on the Ondansetron page.
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