Drug interactions
Formoterol + Quinidine
Severity: Major
Formoterol and Quinidine: major interaction.
Last updated Sources: US FDA label
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
Quinidine is a classic cause of QT prolongation and torsades de pointes. Formoterol may add to this effect and lower potassium, so the combination can substantially increase the risk of life-threatening arrhythmia.
What this interaction means in plain words
Formoterol and Quinidine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Formoterol belongs to Respiratory; Quinidine belongs to Anti Parasitic.
Why it happens
Additive QT prolongation, with beta-2 agonist induced hypokalemia amplifying quinidine proarrhythmia.
What to do
Avoid if possible or use an alternative bronchodilator. If combined, monitor ECG continuously or frequently and keep potassium and magnesium normal.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
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 Quinidine
- Adagrasib + Quinidine Contraindicated
- Arsenic trioxide + Quinidine Contraindicated
- Artemether / lumefantrine + Quinidine Contraindicated
- Chloroquine + Quinidine Contraindicated
- Dofetilide + Quinidine Contraindicated
- Dronedarone + Quinidine Contraindicated
Frequently asked questions
Can I take Formoterol with Quinidine?
MediHelp rates the interaction as major. Formoterol and Quinidine can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Quinidine is a classic cause of QT prolongation and torsades de pointes. Formoterol may add to this effect and lower potassium, so the combination can substantially increase the risk of life-threatening arrhythmia.
How serious is the interaction between Formoterol and Quinidine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid if possible or use an alternative bronchodilator. If combined, monitor ECG continuously or frequently and keep potassium and magnesium normal.
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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