Drug interactions
Arsenic trioxide + Thioridazine
Severity: Contraindicated
Arsenic trioxide and Thioridazine: contraindicated 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
Arsenic trioxide has a boxed warning for QT prolongation and torsades de pointes, and thioridazine is a potent QT-prolonging agent. The combination greatly increases the risk of fatal arrhythmia.
What this interaction means in plain words
Arsenic trioxide 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.
Arsenic trioxide belongs to Oncology; Thioridazine belongs to Central Nervous System.
Why it happens
Additive QT prolongation through cardiac ion channel effects.
What to do
Avoid the combination and use a non-QT-prolonging alternative to thioridazine. Keep potassium and magnesium normal and monitor ECG throughout arsenic therapy.
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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References
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 Arsenic trioxide
- Amiodarone + Arsenic trioxide Contraindicated
- Amisulpride + Arsenic trioxide Contraindicated
- Arsenic trioxide + Clomipramine Contraindicated
- Arsenic trioxide + Dronedarone Contraindicated
- Arsenic trioxide + Fluphenazine Contraindicated
- Arsenic trioxide + Gemifloxacin Contraindicated
Frequently asked questions
Can I take Arsenic trioxide with Thioridazine?
MediHelp rates the interaction as contraindicated. Arsenic trioxide 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. Arsenic trioxide has a boxed warning for QT prolongation and torsades de pointes, and thioridazine is a potent QT-prolonging agent. The combination greatly increases the risk of fatal arrhythmia.
How serious is the interaction between Arsenic trioxide 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 and use a non-QT-prolonging alternative to thioridazine. Keep potassium and magnesium normal and monitor ECG throughout arsenic therapy.
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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