Drug interactions
Metaproterenol + Thioridazine
Severity: Major
Metaproterenol and Thioridazine: major 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
Thioridazine prolongs the QT interval, and beta2-agonists such as metaproterenol can cause tachycardia, hypokalemia and arrhythmias at higher doses. Together they may raise the risk of ventricular arrhythmias including torsades de pointes, especially in patients with heart disease or electrolyte disturbances.
What this interaction means in plain words
Metaproterenol and Thioridazine 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.
Why it happens
Additive proarrhythmic effects: QT prolongation by thioridazine plus beta2-agonist-induced tachycardia and potassium lowering.
What to do
Avoid the combination where possible, especially with oral or high-dose metaproterenol. If used, check serum potassium and magnesium and obtain an ECG to monitor the QTc.
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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Other interactions of Thioridazine
- Abiraterone + Thioridazine Contraindicated
- Adagrasib + Thioridazine Contraindicated
- Amiodarone + Thioridazine Contraindicated
- Amisulpride + Thioridazine Contraindicated
- Amitriptyline + Thioridazine Contraindicated
- Amoxapine + Thioridazine Contraindicated
Frequently asked questions
Can I take Metaproterenol with Thioridazine?
MediHelp rates the interaction as major. Metaproterenol and Thioridazine 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. Thioridazine prolongs the QT interval, and beta2-agonists such as metaproterenol can cause tachycardia, hypokalemia and arrhythmias at higher doses. Together they may raise the risk of ventricular arrhythmias including torsades de pointes, especially in patients with heart disease or electrolyte disturbances.
How serious is the interaction between Metaproterenol and Thioridazine?
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 the combination where possible, especially with oral or high-dose metaproterenol. If used, check serum potassium and magnesium and obtain an ECG to monitor the QTc.
What other medicines interact with Thioridazine?
MediHelp also lists interactions of Thioridazine with, for example, Abiraterone, Adagrasib, Amiodarone. The full list is on the Thioridazine page.
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