Gonadorelin
Hormonal and Signaling
ABOUT
Gonadorelin is synthetic gonadotropin-releasing hormone, formerly approved as Factrel for diagnostic pituitary testing. No FDA-approved product is currently marketed in the United States.
EVIDENCE OVERVIEW
Supported by controlled human trials
WHAT THIS MEANS
Established. Review the research and limitations before relying on this record.
IDENTITY
HALF-LIFE
HOW IT IS THOUGHT TO WORK
A decapeptide identical to native hypothalamic GnRH. Pulsatile administration activates pituitary GnRH receptors on gonadotrophs, driving physiological LH and FSH release. Continuous or supraphysiological dosing does the opposite - it downregulates the receptor and suppresses gonadotropin output. That dose-pattern dependence is the single most important fact about this molecule and is the basis of both its diagnostic use and, in long-acting analogues, of medical castration.
PHARMACOKINETICS
Elimination half-life of roughly 2 to 10 minutes after subcutaneous or intravenous administration, reflecting rapid enzymatic degradation. The extreme brevity is why the pulsatile clinical product (Lutrepulse) required a programmable infusion pump rather than intermittent injection.
REVIEW
PUBLISHED PAIR RECORDS
with Kisspeptin-10
Sequential steps in the same reproductive axisKisspeptin-10 and gonadorelin act at different points on one pathway rather than on two. Kisspeptin acts upstream, on KISS1R-expressing GnRH neurons, to drive GnRH release; gonadorelin is GnRH itself, acting directly on pituitary gonadotrophs. Giving both does not recruit a second mechanism - it stimulates the same axis at two consecutive points, and the downstream step is the shared bottleneck. Dose pattern matters more than dose for both: pulsatile GnRH stimulates gonadotropin release while continuous or supraphysiological exposure downregulates the receptor and suppresses output, and gonadotropin responses to kisspeptin have been shown to desensitise under sustained exposure in animal work. A schedule that produces continuous rather than pulsatile stimulation can therefore invert the intended effect. Peppy reports curated pharmacology, not a safety verdict. A prescriber or pharmacist should review any intended combination.
Reviewed 21 Aug 2026HUMAN EVIDENCE
Factrel was FDA-approved under NDA 017866 for the GnRH stimulation test evaluating anterior pituitary gonadotroph function; patients with hypothalamic or pituitary dysfunction showed subnormal or absent LH responses. It and the pulsatile Lutrepulse product were both discontinued in the United States for commercial reasons, not for safety or efficacy findings. As of 2026 there is no approved gonadorelin product marketed in the US, and supply is compounded.
REPORTED EFFECTS
The historical safety record is that of a short-exposure diagnostic agent given under supervision, which does not characterise repeated long-term administration. Because no approved product is marketed, compounded material is not verified against a label standard for identity or purity. No regulator has approved this substance for the use described here, so there is no label-verified dose, purity standard, or safety monitoring requirement behind it.
RESEARCH LIMITATIONS
This is a source-backed summary, not a recommendation. Read the mechanism, pharmacokinetic, human-evidence and reported-effect fields separately: a mechanism is not an outcome. Availability, legal status and product quality differ by jurisdiction; consult a qualified clinician.
CURATED SOURCES · 2