Siponimod, marketed under the brand name Mayzent, is an oral sphingosine-1-phosphate (S1P) receptor modulator used in the management of multiple sclerosis.
It is indicated for relapsing forms of multiple sclerosis, including secondary progressive MS with active disease. Siponimod binds selectively to S1P₁ and S1P₅ receptors on lymphocytes, preventing their egress from lymph nodes and reducing inflammatory damage in the central nervous system.
The primary gene affecting siponimod metabolism is CYP2C9, which encodes a cytochrome P450 enzyme in the liver responsible for converting siponimod into inactive metabolites. Cytochrome P450 enzymes process many medications, influencing drug clearance.
Genetic variants in CYP2C9 can decrease or increase enzyme activity. Reduced‐function alleles slow metabolism, raising drug exposure and risk of adverse effects, while increased‐function alleles may clear the drug too quickly, risking subtherapeutic levels.
CYP2C9 genotypes classify patients into ultra‐rapid/rapid, normal, intermediate, and poor metabolizers, which directly influence siponimod plasma concentrations. Poor metabolizers have significantly higher exposure and greater risk of toxicity, intermediate metabolizers require dose adjustment, and ultra‐rapid metabolizers may clear the drug more quickly, potentially reducing efficacy.
Want to know what your genetics say about how you'll respond to Siponimod?
A Gene2Rx report reads your own DNA to show how it may affect your response to Siponimod and your other medications.
{# data-track routes these through the sitewide cta_click listener in base.html, which attaches page_type / drug_name / guide_slug from the server-resolved page context. This one file instruments the mid-article CTA on ~114 content pages. #} Find out todayThe following dosing guidelines are based on the available guidelines for CYP2C9 genotypes from the FDA.
| Phenotype | Clinical Consequence | Guideline Recommendation |
|---|---|---|
| Normal Metabolizer | Expected siponimod exposure and efficacy similar to clinical trial population | Initiate with standard titration: 0.25 mg once daily for 4 days, 0.5 mg once daily for 3 days, 0.75 mg once daily for 3 days, then maintenance dose of 2 mg once daily. |
| Intermediate Metabolizer | Increased siponimod exposure and higher systemic concentration | Use reduced maintenance dose: follow standard titration, then maintain at 1 mg once daily. |
| Poor Metabolizer | Significantly increased siponimod exposure; elevated risk of adverse effects | Contraindicated; do not use siponimod in patients with CYP2C9 *3/*3 genotype. |
| Indeterminate | Unknown impact | Initiate therapy with recommended starting dose (standard titration). |
| Not available | Unknown impact | Initiate therapy with recommended starting dose (standard titration). |
For patients with reduced or absent CYP2C9 activity who cannot take siponimod, alternative multiple sclerosis therapies such as fingolimod, ozanimod, or other disease-modifying treatments may be considered. These examples are based on guideline recommendations and are not medical advice.
See the full list of drugs affected by each gene:
See how your genetics affect each product Siponimod shows up in:
Interested in learning more about how your genetics may affect your response to medication? Get started with Gene2Rx today.
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