Drug interactions
Conivaptan + Zafirlukast
Severity: Moderate
Conivaptan 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
Conivaptan is a CYP3A4 substrate and its levels can rise with CYP3A4 inhibitors. Zafirlukast is only a weak inhibitor, so the effect is probably small, but excessive conivaptan effect could cause overly rapid sodium correction.
What this interaction means in plain words
Conivaptan 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
Zafirlukast may inhibit CYP3A4 metabolism of conivaptan.
What to do
Monitor serum sodium frequently during conivaptan infusion to avoid overly rapid correction, and adjust or stop the infusion if the rate of rise is excessive.
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 Conivaptan with Zafirlukast?
MediHelp rates the interaction as moderate. Conivaptan 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. Conivaptan is a CYP3A4 substrate and its levels can rise with CYP3A4 inhibitors. Zafirlukast is only a weak inhibitor, so the effect is probably small, but excessive conivaptan effect could cause overly rapid sodium correction.
How serious is the interaction between Conivaptan 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 serum sodium frequently during conivaptan infusion to avoid overly rapid correction, and adjust or stop the infusion if the rate of rise is excessive.
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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