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. |
| Molecular Weight | 1279.5 |
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 | Risk cannot be ruled out. There are no adequate and well-controlled studies in pregnant women. Animal studies have shown teratogenic effects at high doses. |
| 2nd trimester | Use only if potential benefit justifies potential risk to the fetus. GnRH agonists may cause fetal harm. |
| 3rd trimester | Use only if potential benefit justifies potential risk to the fetus. May cause hormonal disruption. |
Clinical note
Comprehensive clinical and safety monograph for SUPPRELIN (SUPPRELIN).
| Placental transfer | GnRH agonists are known to cross the placenta in animals; human data is limited but transfer is assumed. |
| Breastfeeding | Not recommended due to potential for serious adverse reactions in nursing infants. Excretion into human milk is unknown. |
■ FDA Black Box Warning
None
| Serious Effects |
Hypersensitivity to histrelin or any component of the formulationPregnancy
| 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 |
| Food/Dietary | No known food interactions. Take with or without food. No specific dietary restrictions. |
| Clinical Pearls |
Loading safety data…
| Lactation Rating |
| L5 - Contraindicated |
| 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. |
| 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. |
| Supprelin (histrelin acetate) is a GnRH agonist implant for central precocious puberty. Monitor for initial flare (3-4 weeks) of pubertal symptoms. Implant provides 12-month suppression. Palpate implant site monthly; if non-palpable, verify placement via ultrasound or MRI. Discontinuation leads to reversible puberty. Avoid in pregnancy (category X). Measure LH, FSH, and sex steroids at baseline and 1-2 months post-implant. |
| Patient Advice | This implant slowly releases medication for 12 months to pause early puberty. · The implant is placed under the skin of the upper arm; do not manipulate or apply pressure. · Notify healthcare provider immediately if the implant cannot be felt, or if signs of infection (redness, swelling, pain) occur. · Report any vaginal bleeding, breast development, or growth spurts (possible initial flare). · Do not become pregnant; use effective contraception. If pregnancy occurs, contact doctor immediately. · Regular follow-up visits are required to monitor growth and hormone levels. |