Drug interactions
Fostemsavir + Thioridazine
Severity: Major
Fostemsavir and Thioridazine: 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
Fostemsavir has been associated with QT prolongation at supratherapeutic doses, and thioridazine is a strong QT-prolonging drug. Together the risk of torsades de pointes may rise, especially with other risk factors.
What this interaction means in plain words
Fostemsavir 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.
Fostemsavir belongs to Anti Virals; Thioridazine belongs to Central Nervous System.
Why it happens
Additive QTc interval prolongation.
What to do
Avoid if possible; otherwise obtain baseline and follow-up ECGs and correct potassium and magnesium. Consider an antipsychotic with less QT effect.
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 Thioridazine
- Abiraterone + Thioridazine Contraindicated
- Adagrasib + Thioridazine Contraindicated
- Amiodarone + Thioridazine Contraindicated
- Amisulpride + Thioridazine Contraindicated
- Amitriptyline + Thioridazine Contraindicated
- Amoxapine + Thioridazine Contraindicated
Other interactions of Fostemsavir
- Apalutamide + Fostemsavir Contraindicated
- Carbamazepine + Fostemsavir Contraindicated
- Enzalutamide + Fostemsavir Contraindicated
- Fostemsavir + Mitotane Contraindicated
- Fostemsavir + Phenytoin Contraindicated
- Fostemsavir + Rifampicin Contraindicated
Frequently asked questions
Can I take Fostemsavir with Thioridazine?
MediHelp rates the interaction as major. Fostemsavir 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. Fostemsavir has been associated with QT prolongation at supratherapeutic doses, and thioridazine is a strong QT-prolonging drug. Together the risk of torsades de pointes may rise, especially with other risk factors.
How serious is the interaction between Fostemsavir 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 if possible; otherwise obtain baseline and follow-up ECGs and correct potassium and magnesium. Consider an antipsychotic with less QT effect.
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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