Drug interactions
Ethotoin + Quinidine
Severity: Moderate
Ethotoin and Quinidine: 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
Ethotoin is a hydantoin anticonvulsant related to phenytoin, which strongly induces quinidine metabolism. By analogy ethotoin may lower quinidine concentrations and reduce antiarrhythmic effect. Direct data for ethotoin are limited.
What this interaction means in plain words
Ethotoin and Quinidine 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
Probable induction of CYP3A4-mediated quinidine metabolism by ethotoin, extrapolated from phenytoin.
What to do
Monitor quinidine serum concentrations and ECG response when starting or stopping ethotoin. Increase the quinidine dose if needed, and reduce it again when ethotoin is withdrawn.
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 Quinidine
- Adagrasib + Quinidine Contraindicated
- Arsenic trioxide + Quinidine Contraindicated
- Artemether / lumefantrine + Quinidine Contraindicated
- Chloroquine + Quinidine Contraindicated
- Dofetilide + Quinidine Contraindicated
- Dronedarone + Quinidine Contraindicated
Frequently asked questions
Can I take Ethotoin with Quinidine?
MediHelp rates the interaction as moderate. Ethotoin and Quinidine 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. Ethotoin is a hydantoin anticonvulsant related to phenytoin, which strongly induces quinidine metabolism. By analogy ethotoin may lower quinidine concentrations and reduce antiarrhythmic effect. Direct data for ethotoin are limited.
How serious is the interaction between Ethotoin and Quinidine?
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 quinidine serum concentrations and ECG response when starting or stopping ethotoin. Increase the quinidine dose if needed, and reduce it again when ethotoin is withdrawn.
What other medicines interact with Quinidine?
MediHelp also lists interactions of Quinidine with, for example, Adagrasib, Arsenic trioxide, Artemether / lumefantrine. The full list is on the Quinidine page.
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