Drug interactions
Tetrabenazine + Thioridazine
Severity: Contraindicated
Tetrabenazine and Thioridazine: contraindicated 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 prolong the QTc interval, and thioridazine carries a particularly high risk of torsades de pointes. Tetrabenazine is also metabolized via CYP2D6, which thioridazine inhibits, raising tetrabenazine metabolite exposure. Together they increase the risk of serious ventricular arrhythmia.
What this interaction means in plain words
Tetrabenazine and Thioridazine are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two.
Tetrabenazine belongs to Central Nervous System; Thioridazine belongs to Central Nervous System.
Why it happens
Additive QT prolongation, plus CYP2D6 inhibition by thioridazine increasing active tetrabenazine metabolites.
What to do
Avoid the combination; thioridazine labeling contraindicates use with other QT-prolonging drugs. Choose an alternative antipsychotic with lower QT risk if tetrabenazine is required.
What to ask your pharmacist
- Is there an alternative to one of these two medicines for me?
- If both are essential, who is monitoring me and how often?
- Which symptoms mean I should stop and seek help straight away?
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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
Other interactions of Tetrabenazine
- Dronedarone + Tetrabenazine Contraindicated
- Isocarboxazid + Tetrabenazine Contraindicated
- Linezolid + Tetrabenazine Contraindicated
- Phenelzine + Tetrabenazine Contraindicated
- Pimozide + Tetrabenazine Contraindicated
- Procarbazine + Tetrabenazine Contraindicated
Frequently asked questions
Can I take Tetrabenazine with Thioridazine?
MediHelp rates the interaction as contraindicated. Tetrabenazine and Thioridazine are not normally used together. Taking them at the same time is expected to cause harm or make one of them unsafe, so a different medicine is usually chosen for one of the two. Both drugs prolong the QTc interval, and thioridazine carries a particularly high risk of torsades de pointes. Tetrabenazine is also metabolized via CYP2D6, which thioridazine inhibits, raising tetrabenazine metabolite exposure. Together they increase the risk of serious ventricular arrhythmia.
How serious is the interaction between Tetrabenazine and Thioridazine?
MediHelp rates it contraindicated, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid the combination; thioridazine labeling contraindicates use with other QT-prolonging drugs. Choose an alternative antipsychotic with lower QT risk if tetrabenazine is required.
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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