Drug interactions
Formoterol + Ketoconazole
Severity: Moderate
Formoterol and Ketoconazole: 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
Ketoconazole prolongs the QT interval and formoterol can add to QT effects and lower potassium. Together they may increase the risk of ventricular arrhythmia, particularly in patients with cardiac risk factors.
What this interaction means in plain words
Formoterol and Ketoconazole 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.
Formoterol belongs to Respiratory; Ketoconazole belongs to Anti Fungals.
Why it happens
Additive QT prolongation; ketoconazole's CYP3A4 and P-gp inhibition is unlikely to meaningfully alter inhaled formoterol exposure.
What to do
Obtain ECG and electrolyte checks in at-risk patients and correct hypokalemia. Consider an alternative antifungal if QTc lengthens.
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 Formoterol
- Adagrasib + Formoterol Major
- Amiodarone + Formoterol Major
- Amisulpride + Formoterol Major
- Amitriptyline + Formoterol Major
- Amoxapine + Formoterol Major
- Arformoterol + Formoterol Major
Other interactions of Ketoconazole
- Alfuzosin + Ketoconazole Contraindicated
- Alprazolam + Ketoconazole Contraindicated
- Avanafil + Ketoconazole Contraindicated
- Conivaptan + Ketoconazole Contraindicated
- Dihydroergotamine intranasal + Ketoconazole Contraindicated
- Dihydroergotamine + Ketoconazole Contraindicated
Frequently asked questions
Can I take Formoterol with Ketoconazole?
MediHelp rates the interaction as moderate. Formoterol and Ketoconazole 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. Ketoconazole prolongs the QT interval and formoterol can add to QT effects and lower potassium. Together they may increase the risk of ventricular arrhythmia, particularly in patients with cardiac risk factors.
How serious is the interaction between Formoterol and Ketoconazole?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Obtain ECG and electrolyte checks in at-risk patients and correct hypokalemia. Consider an alternative antifungal if QTc lengthens.
What other medicines interact with Formoterol?
MediHelp also lists interactions of Formoterol with, for example, Adagrasib, Amiodarone, Amisulpride. The full list is on the Formoterol page.
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