SIPONIMOD
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SIPONIMOD (SIPONIMOD).
Siponimod is a sphingosine-1-phosphate (S1P) receptor modulator that binds with high affinity to S1P receptors 1 and 5 on lymphocytes, blocking the egress of lymphocytes from lymph nodes, thereby reducing peripheral lymphocyte counts and attenuating inflammatory demyelination in the central nervous system.
| Metabolism | Siponimod is primarily metabolized by CYP2C9 and to a lesser extent by CYP3A4. It undergoes extensive metabolism, mainly via hydroxylation and oxidation, followed by conjugation. |
| Excretion | Siponimod is excreted primarily via fecal/biliary routes (approximately 77% of the administered dose) and to a lesser extent in urine (about 21%). Unchanged siponimod accounts for about 1.5% of the dose in feces and 1.1% in urine, indicating extensive metabolism. |
| Half-life | The terminal elimination half-life of siponimod is approximately 30 hours (range 20–40 hours). This supports once-daily dosing without loading dose requirements, as steady state is achieved in approximately 5–6 days. |
| Protein binding | Siponimod is extensively bound to plasma proteins, with a fraction unbound of approximately 0.1%. It primarily binds to albumin, with minor binding to alpha-1-acid glycoprotein. |
| Volume of Distribution | The volume of distribution (Vd) of siponimod is approximately 1.0 L/kg (range 0.7–1.3 L/kg), indicating extensive tissue distribution and penetration into the central nervous system, which is relevant for its therapeutic effects in multiple sclerosis. |
| Bioavailability | The absolute oral bioavailability of siponimod is approximately 84% (range 70–95%). Food does not affect the extent of absorption but may slightly delay the time to peak concentration. |
| Onset of Action | Following oral administration, siponimod shows a dose-dependent reduction in lymphocyte count within 2–4 hours, reflecting rapid pharmacological effect. Maximal lymphopenia is typically achieved within 6–8 hours. |
| Duration of Action | The pharmacodynamic effect on lymphocyte counts persists for approximately 2–4 weeks after discontinuation, consistent with its half-life and gradual washout. This duration guides monitoring for lymphocyte recovery after treatment cessation. |
Initial dose: 0.25 mg orally once daily for 4 days, then 0.5 mg orally once daily thereafter. Maintenance dose: 1 mg orally once daily starting from day 5.
| Dosage form | TABLET |
| Renal impairment | No dosage adjustment required for mild to moderate renal impairment. Not recommended in patients with severe renal impairment (eGFR <30 mL/min/1.73 m²). |
| Liver impairment | Contraindicated in patients with severe hepatic impairment (Child-Pugh class C). No dosage adjustment recommended for mild (Child-Pugh class A) or moderate (Child-Pugh class B) hepatic impairment. |
| Pediatric use | Safety and efficacy not established in pediatric patients (age <18 years). No standard dosing recommended. |
| Geriatric use | No specific dosage adjustment required for elderly patients (≥65 years). Use with caution due to increased potential for comorbidities and adverse effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SIPONIMOD (SIPONIMOD).
| Breastfeeding | Siponimod is excreted in animal milk. No human data exist; therefore, a risk to the breastfed infant cannot be excluded. The decision to breastfeed should consider the mother's clinical need for siponimod, the potential for adverse effects in the infant (including immunosuppression), and the drug's long elimination half-life. M/P ratio is unknown. |
| Teratogenic Risk | Siponimod is contraindicated in pregnancy based on animal studies showing embryofetal toxicity (including malformations, reduced fetal weight, and increased resorption) at exposures below the human therapeutic dose. The drug is known to cause fetal harm across all trimesters. Women of childbearing potential must use effective contraception during treatment and for 10 days after discontinuation. |
■ FDA Black Box Warning
WARNING: INCREASED RISK OF INFECTIONS, MACULAR EDEMA, BRADYARRHYTHMIA, AND ATRIOVENTRICULAR BLOCK. Siponimod may increase susceptibility to infections, including serious and life-threatening infections such as cryptococcal meningitis. Macular edema can occur, particularly in patients with a history of uveitis or diabetes mellitus. Initiation of treatment may cause a transient decrease in heart rate and atrioventricular conduction delays; therefore, ECG monitoring is required at treatment initiation. Siponimod is contraindicated in patients with recent myocardial infarction, unstable ischemic heart disease, stroke, TIA, decompensated heart failure, or Mobitz type II second-degree or third-degree AV block, sick sinus syndrome, or sinoatrial heart block unless a pacemaker is in place.
| Serious Effects |
["CYP2C9*3/*3 genotype","History of myocardial infarction, unstable ischemic heart disease, stroke, transient ischemic attack (TIA), decompensated heart failure, or Mobitz type II second-degree or third-degree AV block, sick sinus syndrome, or sinoatrial heart block unless patient has a pacemaker","Severe untreated sleep apnea","Hypersensitivity to siponimod or any of its excipients"]
| Precautions | ["Risk of infections (including opportunistic infections)","Macular edema (monitor ophthalmologic evaluation)","Bradyarrhythmia and AV conduction delays (monitor at initiation)","Respiratory effects (reductions in pulmonary function)","Hepatic injury (monitor liver enzymes)","Increased blood pressure (monitor blood pressure)","Fetal risk (contraindicated in pregnancy)","Mild to moderate decrease in pulmonary function tests","Cutaneous malignancies (monitor skin)","Immune system effects (avoid live vaccines)"] |
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| Fetal Monitoring | For women unintentionally exposed during pregnancy, perform fetal ultrasound to assess for structural anomalies. Monitor fetal growth via serial ultrasound throughout pregnancy. Monitor for maternal bradycardia, hypertension, and liver function abnormalities. After birth, monitor the infant for signs of immunosuppression or infection. |
| Fertility Effects | In animal studies, siponimod did not adversely affect male or female fertility. There is no evidence of reduced fertility in humans, but caution is warranted due to potential luteinizing hormone suppression (based on S1P receptor modulation). Women of childbearing potential should be counseled on contraception. |