Drug interactions
Ethotoin + Zafirlukast
Severity: Moderate
Ethotoin and Zafirlukast: 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
Zafirlukast inhibits CYP2C9, which contributes to hydantoin anticonvulsant metabolism, so ethotoin levels could rise. Evidence is limited for ethotoin specifically, and it is extrapolated from phenytoin.
What this interaction means in plain words
Ethotoin and Zafirlukast 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
Inhibition of CYP2C9 by zafirlukast may reduce ethotoin clearance.
What to do
Monitor for signs of hydantoin toxicity such as nystagmus, ataxia and sedation, and adjust the ethotoin dose based on clinical response.
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 Zafirlukast
- Pimozide + Zafirlukast Contraindicated
- Lomitapide + Zafirlukast Major
- Nilotinib + Zafirlukast Major
- Warfarin + Zafirlukast Major
- Apalutamide + Zafirlukast Moderate
- Carbamazepine + Zafirlukast Moderate
Frequently asked questions
Can I take Ethotoin with Zafirlukast?
MediHelp rates the interaction as moderate. Ethotoin and Zafirlukast 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. Zafirlukast inhibits CYP2C9, which contributes to hydantoin anticonvulsant metabolism, so ethotoin levels could rise. Evidence is limited for ethotoin specifically, and it is extrapolated from phenytoin.
How serious is the interaction between Ethotoin and Zafirlukast?
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 signs of hydantoin toxicity such as nystagmus, ataxia and sedation, and adjust the ethotoin dose based on clinical response.
What other medicines interact with Zafirlukast?
MediHelp also lists interactions of Zafirlukast with, for example, Pimozide, Lomitapide, Nilotinib. The full list is on the Zafirlukast page.
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