Drug interactions
Efavirenz + Meperidine
Severity: Moderate
Efavirenz and Meperidine: 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 induces CYP3A4 and CYP2B6, which may shift meperidine metabolism toward more normeperidine, its neurotoxic metabolite. Parent drug analgesia may be reduced while the risk of normeperidine-related CNS excitation and seizures rises, particularly with repeated dosing or renal impairment.
What this interaction means in plain words
Efavirenz and Meperidine 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; Meperidine belongs to Musculoskeletal.
Why it happens
Enzyme induction by efavirenz increases N-demethylation of meperidine to the neurotoxic metabolite normeperidine.
What to do
Monitor for reduced analgesia and for tremor, myoclonus or seizures; limit meperidine to short courses. Consider an alternative opioid such as morphine if repeated dosing is 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 Meperidine
- Alvimopan + Meperidine Contraindicated
- Isocarboxazid + Meperidine Contraindicated
- Meperidine + Methylene blue Contraindicated
- Meperidine + Olanzapine / samidorphan Contraindicated
- Meperidine + Phenelzine Contraindicated
- Meperidine + Procarbazine Contraindicated
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 Meperidine?
MediHelp rates the interaction as moderate. Efavirenz and Meperidine 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 induces CYP3A4 and CYP2B6, which may shift meperidine metabolism toward more normeperidine, its neurotoxic metabolite. Parent drug analgesia may be reduced while the risk of normeperidine-related CNS excitation and seizures rises, particularly with repeated dosing or renal impairment.
How serious is the interaction between Efavirenz and Meperidine?
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 reduced analgesia and for tremor, myoclonus or seizures; limit meperidine to short courses. Consider an alternative opioid such as morphine if repeated dosing is needed.
What other medicines interact with Meperidine?
MediHelp also lists interactions of Meperidine with, for example, Alvimopan, Isocarboxazid, Methylene blue. The full list is on the Meperidine page.
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