Drug interactions
Tolbutamide + Zafirlukast
Severity: Minor
Tolbutamide 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
Tolbutamide is cleared almost entirely by CYP2C9, which zafirlukast inhibits in vitro. Higher tolbutamide exposure could increase the risk of hypoglycemia, although clinical data are lacking.
What this interaction means in plain words
Tolbutamide 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.
Tolbutamide belongs to Endocrine; Zafirlukast belongs to Respiratory.
Why it happens
Zafirlukast may inhibit CYP2C9-mediated metabolism of tolbutamide.
What to do
Monitor blood glucose when starting or stopping zafirlukast. Reduce the tolbutamide dose if hypoglycemia occurs.
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 Tolbutamide
- Glyburide-metformin + Tolbutamide Major
- Insulin degludec-liraglutide + Tolbutamide Major
- Aceclofenac + Tolbutamide Moderate
- Acemetacin + Tolbutamide Moderate
- Acetylsalicylic acid + Tolbutamide Moderate
- Albiglutide + Tolbutamide Moderate
Frequently asked questions
Can I take Tolbutamide with Zafirlukast?
MediHelp rates the interaction as minor. Tolbutamide 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. Tolbutamide is cleared almost entirely by CYP2C9, which zafirlukast inhibits in vitro. Higher tolbutamide exposure could increase the risk of hypoglycemia, although clinical data are lacking.
How serious is the interaction between Tolbutamide 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: Monitor blood glucose when starting or stopping zafirlukast. Reduce the tolbutamide dose if hypoglycemia occurs.
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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