Drug interactions
Erlotinib + Saquinavir
Severity: Major
Erlotinib 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
Saquinavir, given with ritonavir, inhibits CYP3A4 and may increase erlotinib concentrations. Toxicity such as rash and diarrhea may increase.
What this interaction means in plain words
Erlotinib 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 erlotinib by the boosted saquinavir regimen.
What to do
Avoid if possible. If combined, monitor for erlotinib toxicity and reduce the dose in 50 mg steps for severe reactions.
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 Erlotinib
- Amobarbital + Erlotinib Major
- Apalutamide + Erlotinib Major
- Carbamazepine + Erlotinib Major
- Cobicistat + Erlotinib Major
- Darunavir + Erlotinib Major
- Dexlansoprazole + Erlotinib Major
Frequently asked questions
Can I take Erlotinib with Saquinavir?
MediHelp rates the interaction as major. Erlotinib 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, given with ritonavir, inhibits CYP3A4 and may increase erlotinib concentrations. Toxicity such as rash and diarrhea may increase.
How serious is the interaction between Erlotinib 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 if possible. If combined, monitor for erlotinib toxicity and reduce the dose in 50 mg steps for severe reactions.
What other medicines interact with Erlotinib?
MediHelp also lists interactions of Erlotinib with, for example, Amobarbital, Apalutamide, Carbamazepine. The full list is on the Erlotinib page.
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