Drug interactions
Efavirenz + Ethotoin
Severity: Moderate
Efavirenz and Ethotoin: 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
Efavirenz may alter ethotoin concentrations, with a risk of hydantoin toxicity or loss of seizure control. Data on this specific pair are limited.
What this interaction means in plain words
Efavirenz and Ethotoin 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.
Why it happens
Efavirenz affects hepatic CYP enzymes including CYP2C9 that contribute to hydantoin metabolism; the net effect is not well established.
What to do
Monitor for neurotoxicity and seizure frequency, and measure anticonvulsant response when starting or stopping efavirenz. Adjust the ethotoin dose as needed.
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
Frequently asked questions
Can I take Efavirenz with Ethotoin?
MediHelp rates the interaction as moderate. Efavirenz and Ethotoin 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 may alter ethotoin concentrations, with a risk of hydantoin toxicity or loss of seizure control. Data on this specific pair are limited.
How serious is the interaction between Efavirenz and Ethotoin?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor for neurotoxicity and seizure frequency, and measure anticonvulsant response when starting or stopping efavirenz. Adjust the ethotoin dose as needed.
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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