Drug interactions
Formoterol + Fostemsavir
Severity: Moderate
Formoterol and Fostemsavir: 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
Both drugs can prolong the QTc interval. Fostemsavir has caused QTc prolongation at supratherapeutic doses, so combined use may add to the risk of ventricular arrhythmias, especially with hypokalemia or heart disease.
What this interaction means in plain words
Formoterol and Fostemsavir 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; Fostemsavir belongs to Anti Virals.
Why it happens
Additive pharmacodynamic QTc prolongation.
What to do
Obtain a baseline ECG and monitor QTc in patients with cardiac risk factors, and correct potassium and magnesium. Avoid exceeding recommended fostemsavir doses.
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 Fostemsavir
- Apalutamide + Fostemsavir Contraindicated
- Carbamazepine + Fostemsavir Contraindicated
- Enzalutamide + Fostemsavir Contraindicated
- Fostemsavir + Mitotane Contraindicated
- Fostemsavir + Phenytoin Contraindicated
- Fostemsavir + Rifampicin Contraindicated
Frequently asked questions
Can I take Formoterol with Fostemsavir?
MediHelp rates the interaction as moderate. Formoterol and Fostemsavir 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. Both drugs can prolong the QTc interval. Fostemsavir has caused QTc prolongation at supratherapeutic doses, so combined use may add to the risk of ventricular arrhythmias, especially with hypokalemia or heart disease.
How serious is the interaction between Formoterol and Fostemsavir?
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 a baseline ECG and monitor QTc in patients with cardiac risk factors, and correct potassium and magnesium. Avoid exceeding recommended fostemsavir doses.
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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