PharmaceuticalPeptideGnRH agonistAntineoplastic

Buserelin

Also known as Suprefact · Suprecur

Written by enwyReviewed 5 Aug 20261 sources0 comments

Buserelin is a synthetic GnRH (gonadotropin-releasing hormone) agonist used for prostate cancer, endometriosis, and assisted reproduction. Like all GnRH agonists it first flares gonadotropin release, then downregulates pituitary GnRH receptors to suppress LH, FSH, and sex-steroid output. In bodybuilding circles it is sometimes misused during fertility or PCT experimentation, though its net effect is suppression, not stimulation.

01 Overview

Buserelin is a nonapeptide analogue of GnRH with a substituted position 6 residue that resists enzymatic degradation, giving it far greater potency and duration than native GnRH. It is delivered by subcutaneous injection, intranasal spray, or depot implant.

Continuous exposure to buserelin desensitises pituitary gonadotroph cells, producing a reversible medical castration used to treat hormone-sensitive prostate cancer and to suppress endogenous cycles during IVF stimulation protocols. The initial testosterone or estradiol flare can transiently worsen symptoms, so anti-androgen or add-back cover is often used.

02 Mechanism

Superagonist at the pituitary GnRH receptor: pulsatile dosing stimulates LH/FSH, but sustained dosing downregulates and desensitises receptors, collapsing gonadotropin and gonadal steroid production.

03 Dosing

Tier	Dose	Route	Notes
Nasal maintenance	100 mcg	Insufflated	One 100 mcg spray per nostril, up to 6 times daily
Prostate cancer induction	500 mcg	SubQ	500 mcg SC three times daily for 7 days, then maintenance

04 Effects

Effect	Magnitude	Evidence
Testosterone suppression (chemical castration)Sustained dosing suppresses LH and testosterone to castrate range, the therapeutic goal in prostate cancer.	to castrate levels within ~2-4 weeks	Clinical
Ovarian downregulation for IVFSuppresses premature LH surges, improving control of controlled ovarian stimulation cycles.		Clinical

05 Side effects

Effect	Severity	Frequency	Evidence	Countermeasures
Testosterone flareAn initial surge in LH/testosterone or estradiol during the first days can transiently worsen tumour symptoms or cause bone pain.	Moderate	Universal at initiation	Clinical
Hypogonadal symptomsHot flushes, libido loss, fatigue, and mood change from low sex steroids.	Moderate	Most users	Clinical

06 Legal status

United States

Rx-only

Not FDA-marketed in the US but available elsewhere · as of Jan 2026

United Kingdom

POM

as of Jan 2026

07 References

Buserelin: a review of its pharmacology and therapeutic useDrugs, 1986

08 Discussion0 comments

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This page is reference information, not medical advice. Doses and protocols are documented as they appear in the clinical literature and in practice — describing them is not a recommendation to use them. Countermeasures listed here are not a substitute for a physician. Legal status varies by jurisdiction and changes.