Drug interactions
Mercaptopurine + Siponimod
Severity: Major
Mercaptopurine and Siponimod: 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
Siponimod lowers circulating lymphocyte counts by trapping them in lymph nodes, and mercaptopurine suppresses lymphocytes as well. Together they raise the risk of infection, and the effect may continue for some weeks after siponimod is stopped.
What this interaction means in plain words
Mercaptopurine 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.
Mercaptopurine belongs to Oncology; Siponimod belongs to Central Nervous System.
Why it happens
Additive immunosuppression: S1P receptor modulation reduces lymphocyte egress while thiopurines inhibit lymphocyte proliferation.
What to do
Avoid combining where possible; if necessary, monitor lymphocyte and total blood counts and watch for infection. Allow for the lingering immune effects when switching between therapies.
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 Mercaptopurine
- Adenovirus types 4 and 7 live + Mercaptopurine Contraindicated
- Azathioprine + Mercaptopurine Contraindicated
- Bcg vaccine live + Mercaptopurine Contraindicated
- Febuxostat + Mercaptopurine Contraindicated
- Influenza virus vaccine quadrivalent intranasal + Mercaptopurine Contraindicated
- Mercaptopurine + Smallpox vaccine live Contraindicated
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
Frequently asked questions
Can I take Mercaptopurine with Siponimod?
MediHelp rates the interaction as major. Mercaptopurine 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. Siponimod lowers circulating lymphocyte counts by trapping them in lymph nodes, and mercaptopurine suppresses lymphocytes as well. Together they raise the risk of infection, and the effect may continue for some weeks after siponimod is stopped.
How serious is the interaction between Mercaptopurine 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 combining where possible; if necessary, monitor lymphocyte and total blood counts and watch for infection. Allow for the lingering immune effects when switching between therapies.
What other medicines interact with Mercaptopurine?
MediHelp also lists interactions of Mercaptopurine with, for example, Adenovirus types 4 and 7 live, Azathioprine, Bcg vaccine live. The full list is on the Mercaptopurine page.
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