Gonadorelin is a synthetic copy of gonadotropin-releasing hormone (GnRH), the signaling peptide the hypothalamus uses to control reproduction. Its amino acid sequence is identical to the natural hormone: a decapeptide, pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2, with a pyroglutamic acid at one end and an amidated tail at the other. It has been sold under several brand names including Factrel, Fertagyl, Lutrepulse, and Lutrefact, and is also called GnRH-I or LH-releasing factor.
What it does
Given in short pulses, gonadorelin tells the anterior pituitary to make and release the two gonadotropins, luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Those in turn act on the ovaries or testes. According to DrugBank, it is a synthetic GnRH used to test the function of the pituitary gonadotropes and, when delivered in pulses, to stimulate LH and FSH release.
The timing matters more than almost anything else about this drug. The hypothalamus normally releases GnRH in bursts every 60 to 120 minutes, and the pituitary is built to respond to that rhythm. Deliver gonadorelin the same way and you get sustained gonadotropin output. Deliver it continuously and you get the opposite: the receptors desensitize and hormone output falls. The Canadian product monograph for Lutrepulse notes that continuous, non-pulsatile exposure can temporarily reduce pituitary responsiveness, which is why the natural pulsing pattern has to be reproduced.
That behavior is tied to a very short half-life. The Lutrepulse monograph lists initial and terminal half-lives of roughly 2 to 10 minutes and 10 to 40 minutes. A peptide that clears that fast can only be used as a pulsatile signal if it is dosed by a programmable infusion pump.
The clinical evidence
Gonadorelin's main approved human use is inducing ovulation in women with primary hypothalamic amenorrhea, where the hypothalamus fails to release GnRH on its own. The drug substitutes for that missing pulse. In a published study of 109 women with hypothalamic amenorrhea, pulsatile gonadorelin (Lutrepulse) produced ovulation in the large majority of patients, with the response usually appearing within two to three weeks (Am J Obstet Gynecol, 1990). The other classic use is diagnostic: a single dose as a GnRH stimulation test to probe how the pituitary responds.
There is also a separate veterinary track. The FACTREL label covers treatment of ovarian follicular cysts in cattle and estrous synchronization for fixed-time artificial insemination, given by intramuscular injection. That label confirms the same human-identical decapeptide sequence and a molecular weight of 1182.
Anti-doping status
Gonadorelin and GnRH agonist analogues sit on the World Anti-Doping Agency Prohibited List. They fall under hormone and metabolic modulators, prohibited in male athletes because a GnRH agonist transiently raises LH, FSH, and testosterone. WADA has treated this class as prohibited in men since 2016. Athletes in tested sport should check the current list directly.
A note for buyers
Gonadorelin is an approved peptide drug, but most material sold online is labeled research-use-only and is not a pharmacy product. Independent testing matters here: a certificate of analysis should confirm identity and purity by mass spectrometry and HPLC, since a short peptide can be under-filled, degraded, or simply not what the label claims. peptideone aggregates third-party purity and quality signals so you can see what testing exists for a given vendor rather than taking a product page at its word.
Nothing here is medical or dosing advice, and none of it endorses self-administration. It is a summary of what published and regulatory sources document.