SUPPRELIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SUPPRELIN (SUPPRELIN).
Synthetic decapeptide analog of naturally occurring gonadotropin-releasing hormone (GnRH) that acts as a potent inhibitor of gonadotropin secretion. Initially stimulates, then suppresses pituitary gonadotropin release (LH and FSH), leading to decreased testosterone and estrogen production.
| Metabolism | Primarily hepatic via peptidases; not extensively metabolized by CYP450 enzymes. Metabolites are inactive. |
| Excretion | Primarily renal, with approximately 70-80% of histrelin excreted unchanged in urine; biliary/fecal excretion accounts for about 20-30%. |
| Half-life | Terminal elimination half-life is approximately 4-6 hours following subcutaneous administration; this supports once-daily dosing. |
| Protein binding | Approximately 70% bound to plasma proteins, primarily albumin. |
| Volume of Distribution | Approximately 0.5-1.2 L/kg, indicating distribution throughout total body water and into tissues. |
| Bioavailability | Subcutaneous: approximately 80% bioavailable relative to intravenous administration. |
| Onset of Action | Subcutaneous: suppression of pituitary gonadotropin release occurs within 2-4 weeks of continuous administration; pharmacodynamic effects (LH/FSH suppression) detectable within hours. |
| Duration of Action | Pituitary suppression persists throughout the duration of therapy; after cessation, recovery of gonadotropin secretion typically occurs within 4-12 weeks. |
50 mcg subcutaneously once daily for the first month, then 25 mcg subcutaneously once daily for maintenance. Alternatively, 7.5 mg intramuscularly once monthly.
| Dosage form | INJECTABLE |
| Renal impairment | No adjustment required for GFR ≥30 mL/min; avoid use if GFR <30 mL/min due to lack of data. |
| Liver impairment | No adjustment for Child-Pugh A or B; use with caution in Child-Pugh C, monitor for adverse effects. |
| Pediatric use | Central precocious puberty: 50 mcg/kg subcutaneously once daily; maximum 50 mcg/day; adjust based on response. |
| Geriatric use | No specific adjustment; monitor bone density and cardiovascular status due to increased risk of osteoporosis and thromboembolic events. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SUPPRELIN (SUPPRELIN).
| Breastfeeding | Not recommended during breastfeeding. It is unknown whether histrelin is excreted in human milk; M/P ratio not available. Effects on milk production or the breastfed infant are unknown. |
| Teratogenic Risk | First trimester: There are no adequate and well-controlled studies in pregnant women. Animal studies have shown teratogenic effects, including increased fetal resorptions and malformations at doses lower than the human therapeutic dose. Second and third trimesters: Risk cannot be excluded; potential for fetal harm due to hormonal effects. |
■ FDA Black Box Warning
None
| Serious Effects |
["Hypersensitivity to GnRH, GnRH agonist analogs, or any component","Undiagnosed vaginal bleeding","Pregnancy (Category X): may cause fetal harm"]
| Precautions | ["Transient increase in gonadotropins and sex hormones during initial treatment may worsen signs/symptoms (e.g., bone pain, urinary obstruction) in prostate cancer","Pseudotumor cerebri (intracranial hypertension) reported in children","Bone density loss with prolonged use","Hypersensitivity reactions","QT interval prolongation risk"] |
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| Fetal Monitoring |
| Monitor pregnancy status before and during therapy with periodic pregnancy testing. If pregnancy occurs, discontinue treatment and advise patient of potential fetal risk. |
| Fertility Effects | Supprelin suppresses pituitary gonadotropins, leading to reduced ovarian and testicular function. In women, it may cause infertility during treatment; reversibility after discontinuation is expected but may be delayed. In men, spermatogenesis may be suppressed. |