STRENSIQ
Clinical safety rating: caution
Comprehensive clinical and safety monograph for STRENSIQ (STRENSIQ).
Human recombinant tissue-nonspecific alkaline phosphatase (TNSALP) that hydrolyzes inorganic pyrophosphate (PPi), a natural inhibitor of hydroxyapatite crystal growth, thereby promoting bone mineralization.
| Metabolism | As a protein therapeutic, STRENSIQ is expected to undergo catabolism via general protein degradation pathways; not metabolized by CYP450 enzymes. |
| Excretion | Renal (primarily via proteolytic catabolism into small peptides and amino acids); negligible biliary or fecal elimination. |
| Half-life | Terminal elimination half-life approximately 5.1 days (123 hours) in adults; supports once-weekly subcutaneous dosing for sustained pharmacodynamic effect. |
| Protein binding | Approximately 90% bound to plasma proteins, primarily to low-density lipoprotein receptor-related protein 1 (LRP1) and sortilin. |
| Volume of Distribution | Approximately 0.5 L/kg, indicating distribution primarily within extracellular fluid and plasma; limited extravascular penetration. |
| Bioavailability | Subcutaneous: Approximately 46–50% (estimated) due to incomplete absorption from injection site. |
| Onset of Action | Subcutaneous: Improvement in skeletal abnormalities and biomarkers (e.g., alkaline phosphatase) observed within 3–6 months of initiating therapy. |
| Duration of Action | After last dose, pharmacodynamic effects (elevated alkaline phosphatase, improved skeletal mineralization) persist for several weeks to months, correlating with half-life; continuous treatment required for sustained benefit. |
6 mg/kg administered subcutaneously once weekly.
| Dosage form | SOLUTION |
| Renal impairment | No dose adjustment recommended for renal impairment; clinical trial data limited in severe renal impairment (eGFR <30 mL/min/1.73 m²). |
| Liver impairment | No dose adjustment recommended for hepatic impairment; not studied in Child-Pugh categories. |
| Pediatric use | 6 mg/kg subcutaneously once weekly; based on body weight with no adjustment for age. |
| Geriatric use | No specific dose adjustment required; limited data in patients ≥65 years, but dose is weight-based. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for STRENSIQ (STRENSIQ).
| Breastfeeding | STRENSIQ is a large protein (approximately 180 kDa) and is expected to be present in human milk at very low levels due to its molecular weight. The M/P ratio is unknown; however, endogenous alkaline phosphatase is present in breast milk. The effects on the breastfed infant are unknown. Consider the developmental and health benefits of breastfeeding along with the mother's clinical need for STRENSIQ and any potential adverse effects on the breastfed child. |
| Teratogenic Risk | STRENSIQ (asfotase alfa) is a recombinant bone-targeted enzyme replacement therapy for hypophosphatasia. Animal studies in rats and rabbits showed no evidence of teratogenicity at doses 26-50 times the human systemic exposure. However, there are no adequate and well-controlled studies in pregnant women. Because animal reproduction studies are not always predictive of human response, STRENSIQ should be used during pregnancy only if clearly needed. Based on the mechanism of action, the risk of teratogenicity is considered low. |
■ FDA Black Box Warning
None.
| Serious Effects |
Patients with a history of severe hypersensitivity reactions to STRENSIQ or any of its excipients.
| Precautions | ["Hypersensitivity reactions including anaphylaxis have occurred; monitor during and after administration.","Injection site reactions.","Lipodystrophy at injection sites.","Craniosynostosis and other cranial abnormalities have been reported.","Ectopic calcifications (e.g., in the eyes, kidneys) may occur."] |
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| Fetal Monitoring | No specific maternal or fetal monitoring is mandated beyond standard obstetrical care. However, given the underlying hypophosphatasia, maternal calcium and phosphate levels should be monitored. Fetal monitoring should follow routine prenatal guidelines. There is no evidence of fetal toxicity requiring specialized surveillance. |
| Fertility Effects | No human studies have evaluated the effects of STRENSIQ on fertility. In animal studies, there were no adverse effects on mating, fertility, or reproductive performance in male or female rats treated with asfotase alfa at doses up to 50 times the recommended human dose. Based on available data, STRENSIQ is not expected to impair fertility in humans. |