Drug interactions
Efavirenz + Irinotecan
Severity: Moderate
Efavirenz and Irinotecan: moderate 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
Strong CYP3A4 inducers lower exposure to irinotecan and its active metabolite SN-38, which may reduce antitumor efficacy. Efavirenz is a moderate inducer, so the effect is smaller but still relevant.
What this interaction means in plain words
Efavirenz and Irinotecan can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Efavirenz belongs to Anti Virals; Irinotecan belongs to Oncology.
Why it happens
CYP3A4 induction increases irinotecan metabolism to inactive oxidized metabolites.
What to do
Where possible, use an antiretroviral that does not induce CYP3A4. If it is continued, monitor tumor response and toxicity closely.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Efavirenz
- Cobimetinib + Efavirenz Contraindicated
- Dienogest / estradiol valerate + Efavirenz Contraindicated
- Dihydroergotamine intranasal + Efavirenz Contraindicated
- Dihydroergotamine + Efavirenz Contraindicated
- Doravirine + Efavirenz Contraindicated
- Efavirenz + Elbasvir / grazoprevir Contraindicated
Other interactions of Irinotecan
- Clozapine + Irinotecan Contraindicated
- Irinotecan + Sacituzumab govitecan Contraindicated
- Adenovirus types 4 and 7 live + Irinotecan Major
- Apalutamide + Irinotecan Major
- Atazanavir + Irinotecan Major
- Carbamazepine + Irinotecan Major
Frequently asked questions
Can I take Efavirenz with Irinotecan?
MediHelp rates the interaction as moderate. Efavirenz and Irinotecan can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Strong CYP3A4 inducers lower exposure to irinotecan and its active metabolite SN-38, which may reduce antitumor efficacy. Efavirenz is a moderate inducer, so the effect is smaller but still relevant.
How serious is the interaction between Efavirenz and Irinotecan?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Where possible, use an antiretroviral that does not induce CYP3A4. If it is continued, monitor tumor response and toxicity closely.
What other medicines interact with Efavirenz?
MediHelp also lists interactions of Efavirenz with, for example, Cobimetinib, Dienogest / estradiol valerate, Dihydroergotamine intranasal. The full list is on the Efavirenz page.
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