B tier · viable
A structurally defined decapeptide identical to endogenous GnRH with a genuine regulatory history and physiologically unambiguous pharmacology, but graded B because the US products are discontinued and the modern clinical trials are small, single-arm or underpowered.
gonadorelin
Gonadorelin is synthetic GnRH, the hypothalamic decapeptide that drives pituitary LH and FSH release, historically approved as a diagnostic agent and as a pulsatile-pump therapy for hypogonadotropic hypogonadism. Its physiological effect is well characterised, but the branded US products have been discontinued and the controlled efficacy literature remains small.
the explanation
Gonadorelin is a lab-made copy of the ten-amino-acid signal the brain sends to the pituitary to switch on reproductive hormones. It reliably produces that pituitary response in studies, but the US-approved products are no longer sold and the trials showing real-world fertility benefit are very small.
regulatory status
Discontinued in the United States; formerly FDA-approved; WADA-prohibited in males
Formerly marketed as Factrel (single-dose injection for evaluating hypothalamic-pituitary function) and as the Lutrepulse pulsatile pump for primary hypothalamic amenorrhoea. Both are recorded as discontinued in the United States. The WADA 2026 Prohibited List names gonadotrophin-releasing hormone (GnRH, gonadorelin) and its agonist analogues among testosterone-stimulating peptides prohibited in males. Material sold outside the pharmaceutical supply chain is unapproved and unregulated.
how it works · proposed mechanism
Gonadorelin binds pituitary gonadotroph GnRH receptors, and the pattern of exposure determines whether the pituitary is stimulated or suppressed.
Gonadotroph receptor activation
Binding to the Gq-coupled GnRH receptor triggers phospholipase C signalling and calcium-dependent exocytosis of stored LH and FSH. This is the physiological top of the hypothalamic-pituitary-gonadal axis.
Pulsatile versus continuous divergence
Intermittent exposure maintains receptor expression and sustains gonadotropin secretion, while continuous exposure causes receptor downregulation and profound gonadotropin suppression. The same molecule can therefore stimulate or chemically suppress the axis depending purely on delivery pattern.
Diagnostic axis probing
Because the LH and FSH response to a single GnRH exposure is rapid and quantifiable, gonadorelin was approved as a test of hypothalamic-pituitary reserve. A 100% pituitary response rate was reported in a modern congenital hypogonadotropic hypogonadism cohort.
what’s reported
evidence shape
6 sourcesThe composition of the cited literature by study type. This describes the shape of the evidence, not its quality — and it does not by itself set the grade.
⚠ the catch
The pituitary response to gonadorelin is essentially guaranteed, but a hormone response is not a clinical outcome, and the downstream fertility data come from cohorts of a few dozen patients or fewer. Its US approvals have lapsed, so almost all current supply is unapproved material with no regulatory quality oversight.
key published findings
- Human trial: a prospective, self-controlled multicentre study across three hospitals (Annals of Translational Medicine, 2021) enrolled 28 men with congenital hypogonadotropic hypogonadism, mean age 23.24 +/- 4.63 years, with baseline LH and FSH each below 1 IU/L.
- Human trial: after a 7-day pulsatile GnRH pump trial, FSH rose from a baseline of 0.53 to 5.05 +/- 3.03 IU/L and LH from 0.20 to 2.66 +/- 1.74 IU/L; the rate of pituitary response to pulsatile GnRH was reported as 100%.
- Human trial: among the 6 patients followed to 6 months, testosterone rose from 0.58 +/- 0.82 to 2.50 +/- 1.59 ng/mL, but spermatogenesis was achieved in only 16.67% (1 of 6).
- Human trial (Cochrane review): Bayram, van Wely and Van der Veen identified just 4 randomized trials totalling 57 women for pulsatile GnRH ovulation induction in PCOS; the single reported ongoing-pregnancy odds ratio was 7.5 (95% CI 0.44 to 127), and the reviewers concluded the trials were too small to either prove or discard the value of the treatment.
- Chemistry: PubChem records gonadorelin as C55H75N17O13 with a molecular weight of 1182.3 and CAS 33515-09-2.
limitations of the evidence
- The modern efficacy studies are prospective self-controlled cohorts of roughly 28 patients with only 6 followed long-term, not randomized comparisons against an active alternative.
- The Cochrane review's 4 trials totalled 57 women with follow-up of only 1-3 cycles, giving confidence intervals so wide (0.44 to 127) as to be uninformative.
- Because the US products are discontinued, there is no current FDA label to anchor pharmacokinetic, storage or impurity specifications, and this index could not verify an exact half-life figure from a regulatory source.
documented safety signals
- Continuous rather than pulsatile exposure downregulates the GnRH receptor and suppresses LH, FSH and gonadal steroid output, producing the opposite of the intended effect; this is the documented mechanism by which GnRH agonist analogues achieve chemical castration.
- Prohibited in males under WADA S2, where GnRH and gonadorelin are named explicitly alongside their agonist analogues; use by a male athlete is an anti-doping rule violation.
- In the 28-patient CHH study two mild adverse events were reported (upper respiratory infection and mild nausea), which the investigators judged unrelated to therapy; the cohort is far too small to characterise uncommon harms.
- Ovulation induction with GnRH carries the gonadotropin-class risks of ovarian hyperstimulation and multiple gestation; the Cochrane review noted OHSS occurred in the HMG comparison group.
- No FDA-approved US product currently exists, so material in circulation is unapproved research chemical of unverified identity, purity, sterility and endotoxin content, with peptide-class risks of injection-site reaction and immunogenicity.
- As a hypothalamic releasing factor, gonadorelin acts upstream of the entire reproductive axis, so effects on fertility, bone and gonadal function are systemic rather than localised.
identity
| full name | Gonadorelin (Gonadotropin-Releasing Hormone, GnRH) |
| category | Hormonal |
| modality | peptide |
| formula | C55H75N17O13 |
| molar mass | 1182.3 g/mol |
| cas | 33515-09-2 |
| half-life | Very short; commonly cited in the range of a few minutes, consistent with rapid peptidase cleavage. This index could not confirm an exact figure against a current regulatory label, since the US products have been discontinued. |
| sequence | pGlu-His-Trp-Ser-Tyr-Gly-Leu-Arg-Pro-Gly-NH2 (10 residues, N-terminal pyroglutamate, C-terminal amide) |
laboratory handling
| storage | Peptide-class handling: lyophilised powder stored refrigerated at 2-8 C or frozen, protected from light and moisture. No current FDA label exists to specify approved storage conditions for US products. |
| solubility | Water-soluble decapeptide; supplied as the acetate salt and reconstituted in sterile aqueous diluent. |
| co-studied with | Published comparisons place pulsatile GnRH against combined gonadotropin therapy (hCG plus FSH-containing preparations) for spermatogenesis in congenital hypogonadotropic hypogonadism, with at least one study reporting earlier spermatogenesis on the pulsatile pump. This index does not describe regimens. Note that gonadorelin, hCG and LH are all prohibited in males under the same WADA S2 provision. |
Handling information describes laboratory practice for a research reagent. It is not a preparation guide for use in humans.
the receipts
6 citedPubChem, U.S. National Library of Medicine · 2025 · official
Drugs.com · 2025 · official
World Anti-Doping Agency · 2026 · official
Cochrane Database of Systematic Reviews, CD000412 · 1999 · review
Annals of Translational Medicine · 2021 · observational
American Journal of Men's Health · 2019 · observational
others in Hormonal