Gonadorelin

A synthetic copy of GnRH, the brain's own 10-amino-acid signal to the pituitary. The US approved it as Factrel (1982), a pituitary test, and Lutrepulse (1989), a pump for restoring ovulation; both are now discontinued.

It binds the GnRH receptor on the pituitary, driving release of LH and FSH. Natural GnRH comes in pulses, and pulsed exposure stimulates the system. Steady exposure first causes a brief surge and then shuts the pituitary down, the same effect long-acting drugs like leuprolide use to suppress hormones.

It was used clinically as a single-dose pituitary function test and as a pump delivering pulses to restore ovulation. The Endocrine Society's 2017 guideline still lists pulsatile GnRH as a first-line option for functional hypothalamic amenorrhea. It has also been studied in hypogonadotropic hypogonadism, Kallmann syndrome, delayed puberty and cryptorchidism, and is widely used in veterinary breeding. No published human trial supports its popular use alongside testosterone therapy; the controlled data for that purpose exist for hCG instead.

Former Factrel labeling listed headache, light-headedness, nausea, abdominal discomfort, flushing and injection-site reactions. Rare hypersensitivity, anaphylaxis after multiple doses, antibody formation and one pituitary bleed in a patient with a pituitary tumor were reported. Continuous or too-frequent exposure may suppress rather than stimulate the reproductive axis.

Both US human products (Factrel, Lutrepulse) are discontinued; only veterinary labels remain on DailyMed. It is not on the 503A bulks list or nominations categories, and its compounding eligibility is unclear. WADA prohibits it at all times for males under S2.2.1. Status as of October 2026.