Gonadorelin

Overview

Gonadorelin is a synthetic decapeptide identical to endogenous gonadotropin-releasing hormone (GnRH/LHRH; sequence pyroGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2). It was historically FDA-approved as Factrel (diagnostic GnRH stimulation test) and Lutrepulse (pulsatile IV pump for hypothalamic amenorrhea); both products are discontinued in the US. Gonadorelin remains on the FDA Category 1 bulk substances list and is widely compounded, most commonly as an off-label adjunct to TRT intended to preserve HPG-axis signaling.

Mechanism of Action

Gonadorelin binds the GnRH receptor on anterior-pituitary gonadotrophs, triggering release of LH and FSH that drive testicular testosterone production and spermatogenesis (or ovarian follicular development in women). Signaling is pulse-dependent: intermittent pulses every 60–120 minutes preserve receptor responsiveness, while continuous exposure desensitizes the receptor and paradoxically suppresses LH/FSH — the mechanism by which GnRH agonists such as leuprolide are used to treat prostate cancer and endometriosis.

Research Summary

Factrel (diagnostic) and Lutrepulse (pulsatile ovulation induction) were the historical FDA-approved gonadorelin products; both have been discontinued commercially but gonadorelin remains available via 503A/503B compounding under FDA Category 1. Pulsatile pump delivery is the clinical gold standard for hypothalamic amenorrhea and congenital hypogonadotropic hypogonadism (Tranoulis 2018; Büchter 1998; Zhang 2018/2019). Compounded use as a TRT adjunct (100–200 mcg SubQ 2–3×/week in place of hCG) is widespread in men's-health practice but is off-label and lacks dedicated controlled-trial evidence for that indication.

Dosing Information

Reported Side Effects

• Injection site reactions
• Transient headache
• Nausea (uncommon at low SubQ doses)
• Flushing
• Receptor desensitization with continuous or excessive dosing (paradoxical LH/FSH suppression)

Research References

• The Pulsatile Gonadorelin Pump Induces Earlier Spermatogenesis Than Cyclical Gonadotropin Therapy in Congenital Hypogonadotropic Hypogonadism Men (2019)
• Efficacy and safety of pulsatile gonadotropin-releasing hormone therapy among patients with idiopathic and functional hypothalamic amenorrhea: a systematic review and meta-analysis (2018)
• Pulsatile GnRH or human chorionic gonadotropin/human menopausal gonadotropin as effective treatment for men with hypogonadotropic hypogonadism: a review of 42 cases (1998)