Histrelin
Histrelin is a potent GnRH agonist most often delivered as a 12-month subcutaneous implant (Vantas, Supprelin LA) for advanced prostate cancer and central precocious puberty. It provides sustained pituitary downregulation from a single implant, suppressing sex steroids to castrate or prepubertal levels.
01 Overview
Histrelin is a synthetic nonapeptide GnRH superagonist. Its hydrogel implant slowly releases roughly 50-65 mcg per day over a year, delivering steady receptor desensitisation without repeated injections.
In prostate cancer it maintains castrate testosterone; in central precocious puberty it halts premature pubertal progression, which reverses on removal. As with all agonists there is an initial hormonal flare before suppression sets in.
02 Mechanism
Continuous GnRH-receptor agonism from the implant desensitises pituitary gonadotrophs, abolishing pulsatile LH/FSH secretion and lowering sex steroids.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Prostate cancer implant | 50 mg | SubQ | 50 mg implant (releases ~50 mcg/day) replaced every 12 months |
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Sustained castrate testosteroneA single implant keeps testosterone at castrate levels for a full year. | <50 ng/dL maintained | Clinical | |
| Arrest of precocious pubertyHalts premature pubertal development and preserves adult height potential. | Clinical |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Implant-site reactionsLocal pain, bruising, or occasional implant extrusion at the inner-arm site. | Mild | Common | Clinical | |
| Hypogonadal effectsHot flushes, fatigue, reduced libido, and long-term bone mineral loss. | Moderate | Most users | Clinical |