Drug interactions
Meperidine + Phenytoin
Severity: Moderate
Meperidine and Phenytoin: 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
Phenytoin induces hepatic enzymes and can speed up meperidine clearance, shortening its analgesic effect. It may also raise levels of the neurotoxic metabolite normeperidine, which can lower seizure threshold.
What this interaction means in plain words
Meperidine and Phenytoin 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.
Meperidine belongs to Musculoskeletal; Phenytoin belongs to Central Nervous System.
Why it happens
Induction of hepatic metabolism by phenytoin, increasing meperidine clearance and normeperidine formation.
What to do
Monitor analgesic response and watch for CNS excitation or seizures. Consider an alternative opioid in patients who need repeated dosing.
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 Phenytoin
- Artemether / lumefantrine + Phenytoin Contraindicated
- Bictegravir + Phenytoin Contraindicated
- Cabotegravir + Phenytoin Contraindicated
- Doravirine + Phenytoin Contraindicated
- Elbasvir / grazoprevir + Phenytoin Contraindicated
- Elvitegravir / cobicistat / emtricitabine / tenofovir df + Phenytoin Contraindicated
Frequently asked questions
Can I take Meperidine with Phenytoin?
MediHelp rates the interaction as moderate. Meperidine and Phenytoin 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. Phenytoin induces hepatic enzymes and can speed up meperidine clearance, shortening its analgesic effect. It may also raise levels of the neurotoxic metabolite normeperidine, which can lower seizure threshold.
How serious is the interaction between Meperidine and Phenytoin?
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 analgesic response and watch for CNS excitation or seizures. Consider an alternative opioid in patients who need repeated dosing.
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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