Drug interactions
Quinidine + Zafirlukast
Severity: Moderate
Quinidine 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
Quinidine is partly cleared by CYP3A4 and has a narrow therapeutic index with proarrhythmic risk. Zafirlukast may raise quinidine levels and increase QT prolongation and torsades risk.
What this interaction means in plain words
Quinidine 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.
Quinidine belongs to Anti Parasitic; Zafirlukast belongs to Respiratory.
Why it happens
Inhibition of CYP3A4-mediated quinidine metabolism by zafirlukast.
What to do
Monitor ECG and QT interval, and quinidine levels where available, when zafirlukast is started or stopped. Adjust the quinidine dose as 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 Zafirlukast
- Pimozide + Zafirlukast Contraindicated
- Lomitapide + Zafirlukast Major
- Nilotinib + Zafirlukast Major
- Warfarin + Zafirlukast Major
- Apalutamide + Zafirlukast Moderate
- Carbamazepine + Zafirlukast Moderate
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 Quinidine with Zafirlukast?
MediHelp rates the interaction as moderate. Quinidine 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. Quinidine is partly cleared by CYP3A4 and has a narrow therapeutic index with proarrhythmic risk. Zafirlukast may raise quinidine levels and increase QT prolongation and torsades risk.
How serious is the interaction between Quinidine 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 ECG and QT interval, and quinidine levels where available, when zafirlukast is started or stopped. Adjust the quinidine dose as needed.
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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