Drug interactions
Protriptyline + Thioridazine
Severity: Major
Protriptyline 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
Both drugs can prolong the QTc interval and the combination raises the risk of ventricular arrhythmia. Thioridazine may also raise tricyclic levels through CYP2D6 inhibition, and anticholinergic effects add up.
What this interaction means in plain words
Protriptyline 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 QT prolongation, with possible CYP2D6-mediated increase in protriptyline exposure.
What to do
Avoid the combination where possible and choose an alternative antidepressant with less cardiac effect. If used together, obtain a baseline ECG, monitor QTc, and check electrolytes.
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 Protriptyline with Thioridazine?
MediHelp rates the interaction as major. Protriptyline 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. Both drugs can prolong the QTc interval and the combination raises the risk of ventricular arrhythmia. Thioridazine may also raise tricyclic levels through CYP2D6 inhibition, and anticholinergic effects add up.
How serious is the interaction between Protriptyline 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 and choose an alternative antidepressant with less cardiac effect. If used together, obtain a baseline ECG, monitor QTc, and check electrolytes.
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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