Drug interactions
Ivacaftor + Zafirlukast
Severity: Minor
Ivacaftor and Zafirlukast: minor 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
Ivacaftor is a sensitive CYP3A4 substrate, and zafirlukast may modestly increase its exposure. Labeling advises dose reduction only with moderate or strong inhibitors, so this weak interaction is generally manageable.
What this interaction means in plain words
Ivacaftor and Zafirlukast have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Ivacaftor belongs to Miscellaneous; Zafirlukast belongs to Respiratory.
Why it happens
Weak CYP3A4 inhibition by zafirlukast reduces ivacaftor clearance.
What to do
No dose reduction is generally required; monitor for ivacaftor adverse effects such as headache, abdominal pain and elevated transaminases.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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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 Ivacaftor
- Ensitrelvir + Ivacaftor Contraindicated
- Apalutamide + Ivacaftor Major
- Carbamazepine + Ivacaftor Major
- Clarithromycin + Ivacaftor Major
- Efavirenz + Ivacaftor Major
- Enzalutamide + Ivacaftor Major
Frequently asked questions
Can I take Ivacaftor with Zafirlukast?
MediHelp rates the interaction as minor. Ivacaftor and Zafirlukast have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Ivacaftor is a sensitive CYP3A4 substrate, and zafirlukast may modestly increase its exposure. Labeling advises dose reduction only with moderate or strong inhibitors, so this weak interaction is generally manageable.
How serious is the interaction between Ivacaftor and Zafirlukast?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: No dose reduction is generally required; monitor for ivacaftor adverse effects such as headache, abdominal pain and elevated transaminases.
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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