SUPPRELIN LA
Clinical safety rating: caution
Comprehensive clinical and safety monograph for SUPPRELIN LA (SUPPRELIN LA).
SUPPRELIN LA is a sterile, biodegradable, subcutaneous implant containing histrelin acetate, a synthetic nonapeptide agonist of gonadotropin-releasing hormone (GnRH). After an initial transient increase, continuous administration results in downregulation of pituitary GnRH receptors, leading to suppressed luteinizing hormone (LH) and follicle-stimulating hormone (FSH) secretion, thereby reducing gonadal sex steroid production (testosterone in males, estradiol in females) to castrate levels.
| Metabolism | Histrelin is primarily metabolized via hydrolysis of the C-terminal prolineamide bond and removal of the N-terminal pyroglutamyl residue; specific CYP enzymes are not involved. |
| Excretion | Renal: <5% unchanged; hepatic metabolism; fecal elimination of metabolites. |
| Half-life | Terminal half-life approximately 3-4 hours; clinical suppression of luteinizing hormone and testosterone sustained for 4 weeks due to depot formulation. |
| Protein binding | Approximately 43% bound to albumin; minimal binding to sex hormone-binding globulin. |
| Volume of Distribution | Vd approximately 10-15 L; not clinically significant due to small Vd. |
| Bioavailability | Subcutaneous implant: 100% (systemic delivery); oral: negligible (<1%). |
| Onset of Action | Subcutaneous implant: Suppression of testosterone to castrate levels achieved by week 4. |
| Duration of Action | Subcutaneous implant: Clinical effect (testosterone suppression) persists for 12 months; implant removal reverses effect. |
50 mg subcutaneously once every 12 months (implant placed in inner upper arm).
| Dosage form | IMPLANT |
| Renal impairment | No dose adjustment required for renal impairment. |
| Liver impairment | No dose adjustment required for hepatic impairment. |
| Pediatric use | Not approved for use in pediatric patients (indicated for central precocious puberty in children, but not in standard dosing). |
| Geriatric use | No specific dose adjustment recommended; use with caution due to limited data in elderly. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for SUPPRELIN LA (SUPPRELIN LA).
| Breastfeeding | Unknown if histrelin is excreted in human milk. No M/P ratio available. Caution in breastfeeding due to potential for infant gonadotropin suppression. Consider alternative therapy or discontinue nursing. |
| Teratogenic Risk | Pregnancy Category X. Contraindicated in pregnancy. Histrelin acetate (GnRH agonist) causes fetal harm in animal studies, including increased resorptions and skeletal abnormalities. Risk in all trimesters; use in early pregnancy may disrupt implantation. Avoid in women of childbearing potential unless using effective contraception. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to histrelin or any component of the implant; pregnancy (category X) due to risk of fetal harm; undiagnosed abnormal vaginal bleeding; history of thromboembolic disorders (relative contraindication for use in adults, not pediatric CPP).
| Precautions | Monitor for transient increase in serum estradiol or testosterone during initial treatment, which may cause transient exacerbation of signs of puberty including vaginal bleeding or breast enlargement; monitor bone mineral density loss with prolonged use; risk of psychiatric events including emotional lability and aggression; insertion site reactions including infection, implant extrusion, and granuloma formation; implant removal must be performed by a trained healthcare provider; pseudotumor cerebri has been reported. |
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| Fetal Monitoring |
| Monitor serum estradiol or testosterone levels to confirm suppression. Rule out pregnancy with sensitive test before initiation and monthly during treatment. Monitor bone mineral density with DEXA scan if prolonged use. No specific fetal monitoring required if pregnancy avoided. |
| Fertility Effects | Reversible suppression of pituitary-gonadal axis. In females, inhibits ovulation; in males, suppresses spermatogenesis. Fertility returns after discontinuation, typically within weeks to months. Use may cause temporary infertility during treatment. |