Drug interactions
Arsenic trioxide + Siponimod
Severity: Major
Arsenic trioxide and Siponimod: 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
Arsenic trioxide markedly prolongs the QT interval and can cause torsades de pointes. Siponimod causes bradycardia on initiation, which is a risk factor for torsades.
What this interaction means in plain words
Arsenic trioxide and Siponimod 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.
Arsenic trioxide belongs to Oncology; Siponimod belongs to Central Nervous System.
Why it happens
Additive QT prolongation by arsenic trioxide with siponimod-induced bradycardia.
What to do
Avoid the combination; choose an alternative MS therapy during arsenic trioxide treatment. If it cannot be avoided, obtain cardiology advice and monitor the ECG and 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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References
Other interactions of Siponimod
- Cladribine + Siponimod Contraindicated
- Fingolimod + Siponimod Contraindicated
- Fluconazole + Siponimod Contraindicated
- Influenza virus vaccine quadrivalent intranasal + Siponimod Contraindicated
- Ponesimod + Siponimod Contraindicated
- Siponimod + 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 Siponimod?
MediHelp rates the interaction as major. Arsenic trioxide and Siponimod 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. Arsenic trioxide markedly prolongs the QT interval and can cause torsades de pointes. Siponimod causes bradycardia on initiation, which is a risk factor for torsades.
How serious is the interaction between Arsenic trioxide and Siponimod?
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; choose an alternative MS therapy during arsenic trioxide treatment. If it cannot be avoided, obtain cardiology advice and monitor the ECG and electrolytes.
What other medicines interact with Siponimod?
MediHelp also lists interactions of Siponimod with, for example, Cladribine, Fingolimod, Fluconazole. The full list is on the Siponimod page.
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