ENSPRYNG
Clinical safety rating: caution
Comprehensive clinical and safety monograph for ENSPRYNG (ENSPRYNG).
Satralizumab is a humanized monoclonal antibody that binds to the IL-6 receptor, inhibiting IL-6-mediated signaling and reducing inflammation in the central nervous system.
| Metabolism | Satralizumab is a monoclonal antibody expected to be degraded into small peptides and amino acids via catabolic pathways, not metabolized by CYP450 enzymes. |
| Excretion | Satralizumab is primarily eliminated via intracellular catabolism and subsequent renal excretion of peptides and amino acids. No specific renal or biliary excretion data available for the intact monoclonal antibody. |
| Half-life | 26.3 days (range: 22-35 days) in patients with NMOSD, supporting every 4-week dosing interval. |
| Protein binding | Binds to soluble and membrane-bound IL-6 receptors; not bound to plasma proteins like albumin. Specific binding protein is IL-6 receptor. |
| Volume of Distribution | 6.4 L (central volume) to 9.3 L (steady-state), approximately 0.08-0.12 L/kg, indicating limited extravascular distribution. |
| Bioavailability | Subcutaneous: approximately 85% (range: 65-100%) after SC injection. |
| Onset of Action | Subcutaneous administration: Clinical effect observed within 4-8 weeks based on reduction of relapse rate in clinical trials. |
| Duration of Action | Sustained IL-6 receptor blockade for the entire 4-week dosing interval; duration of clinical effect is continuous with regular dosing. |
120 mg subcutaneously once every 4 weeks.
| Dosage form | INJECTABLE |
| Renal impairment | No dosage adjustment required for GFR ≥15 mL/min. Not studied in ESRD (GFR <15 mL/min) or dialysis. |
| Liver impairment | No dosage adjustment required for mild (Child-Pugh A) to moderate (Child-Pugh B) hepatic impairment. Not studied in severe (Child-Pugh C) hepatic impairment. |
| Pediatric use | Safety and efficacy not established in pediatric patients under 18 years of age. |
| Geriatric use | No specific dosage adjustment recommended; clinical studies included limited number of patients aged 65 and older. Use with caution due to higher risk of infections and comorbidities. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for ENSPRYNG (ENSPRYNG).
| Breastfeeding | No human data. Satralizumab is a large protein likely excreted in low amounts; M/P ratio unknown. Consider benefit of breastfeeding and risk of infant exposure. Caution recommended. |
| Teratogenic Risk | Based on mechanism (IL-6 receptor antagonist), animal studies show increased risk of fetal loss and malformations. Human data limited; avoid first trimester. Second/third trimester: possible increased infection risk in neonate. Consider risks vs benefits. |
| Fetal Monitoring |
■ FDA Black Box Warning
None.
| Serious Effects |
["Active severe infection","Known hypersensitivity to satralizumab or any excipients"]
| Precautions | ["Risk of serious infections including tuberculosis, fungal, bacterial, and viral infections due to immunosuppression","Live vaccines should not be given concurrently","Elevated liver enzymes and potential for hepatic injury","Possible neutropenia and thrombocytopenia"] |
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| Monitor for maternal infections; fetal ultrasound for anomalies if used in first trimester; neonatal monitoring for infections and hematologic abnormalities at delivery. |
| Fertility Effects | IL-6 inhibition may impair follicular development and ovulation; reversible after discontinuation. Limited data in humans. |