Buserelin is a synthetic version of gonadotropin-releasing hormone (GnRH), the brain signal that tells the pituitary to release the hormones controlling the testes and ovaries. Hoechst AG developed it in the 1970s under the code HOE 766, and it reached medical use in 1984. Chemists changed two spots on the natural ten-amino-acid hormone, swapping in a D-serine derivative at position 6 and an ethylamide cap at the end. Those edits make the molecule resist the enzymes that normally chew up GnRH within minutes, so a single dose keeps working far longer and binds the pituitary receptor 20 to 170 times more tightly than the natural hormone does, according to DrugBank.
It is sold as Suprefact, Suprefact Depot, and Suprecur, among other names. CAS number 57982-77-1 covers the free base; the acetate salt used in products is 68630-75-1.
How it works
The counterintuitive part is that a GnRH agonist is used to lower sex hormones. Give buserelin once and you get a short surge: LH and FSH climb, and testosterone or estradiol rises with them. This is the so-called flare. Keep dosing continuously and the pituitary gonadotrope cells stop responding. The receptors downregulate, the signal goes quiet, and sex-hormone output collapses. GnRH analogues like buserelin can drop testosterone or estradiol by roughly 95%, into the range seen after surgical castration (DrugBank).
That chemical shutdown is the whole point in hormone-driven disease.
What the evidence and approvals cover
Buserelin is an approved drug, not an experimental one, in a long list of countries including the UK, Canada, much of Europe, New Zealand, and South Africa. It is not approved or marketed in the United States or Australia. Documented, approved uses include:
- Advanced prostate cancer — palliative hormone suppression in men. An early study published in Cancer Chemotherapy and Pharmacology in 1986 showed a once-monthly depot formulation pushed testosterone to castrate levels as effectively as five-times-daily nasal dosing, with far better compliance (Waxman et al., PubMed).
- Endometriosis and uterine fibroids — by suppressing estradiol.
- Premenopausal breast cancer that depends on estrogen.
- Assisted reproduction (IVF) — used to suppress a woman's own cycle so clinicians can control ovarian stimulation timing.
Routes reflect that range of uses: a nasal spray, subcutaneous injection, and long-acting depot implants dosed monthly or longer.
Regulatory and anti-doping status
For athletes, buserelin is banned. The World Anti-Doping Agency lists it under Section S2 as a GnRH agonist, grouped with deslorelin, goserelin, histrelin, leuprorelin, nafarelin, and triptorelin. WADA's 2024 wording clarified these testosterone-stimulating peptides are prohibited in male athletes (USADA summary). The doping concern traces back to the flare effect, the transient testosterone bump before suppression sets in.
The buyer-quality angle
Where buserelin is approved, it comes as a regulated pharmaceutical made to pharmacopoeia standards. Material sold through research-chemical or gray channels carries none of those guarantees. A peptide this size can be mis-synthesized, contaminated, underdosed, or simply not be what the label claims, and only an independent assay (identity and purity, with a certificate of analysis from an accredited lab) can tell you which. peptideone aggregates third-party lab and vendor signals rather than running its own tests; treat any unverified product as research-use-only material of unknown content.
Nothing here is medical or dosing advice. Buserelin acts on the body's core hormonal axis, and in every approved setting it is used under clinical supervision.