Drug interactions
Efavirenz + Felbamate
Severity: Moderate
Efavirenz and Felbamate: 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 lower felbamate concentrations through CYP3A4 induction, potentially reducing seizure control. Felbamate is also partly renally cleared, so the effect is probably modest.
What this interaction means in plain words
Efavirenz and Felbamate 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; Felbamate belongs to Central Nervous System.
Why it happens
Efavirenz induces CYP3A4 metabolism of felbamate.
What to do
Monitor seizure frequency and felbamate levels, and adjust the dose if control worsens.
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 Felbamate
- Felbamate + Ulipristal Major
- Amisulpride + Felbamate Moderate
- Amitriptyline + Felbamate Moderate
- Apalutamide + Felbamate Moderate
- Asenapine + Felbamate Moderate
- Bosentan + Felbamate Moderate
Frequently asked questions
Can I take Efavirenz with Felbamate?
MediHelp rates the interaction as moderate. Efavirenz and Felbamate 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 lower felbamate concentrations through CYP3A4 induction, potentially reducing seizure control. Felbamate is also partly renally cleared, so the effect is probably modest.
How serious is the interaction between Efavirenz and Felbamate?
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 seizure frequency and felbamate levels, and adjust the dose if control worsens.
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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