Skip to content
approvedHormone Regulation

Buserelin

Also known as: Suprefact, Suprecur, Buserelin Acetate

Buserelin is a synthetic GnRH agonist nonapeptide widely used outside the United States for the treatment of prostate cancer, endometriosis, and as a component of IVF protocols. Marketed as Suprefact and Suprecur, it is available in both intranasal and subcutaneous formulations, as well as implant preparations. While not FDA-approved in the US, buserelin is one of the most commonly prescribed GnRH agonists in Europe, Canada, and Australia. It shares the same mechanism of action as leuprolide and triptorelin — initial gonadotropin stimulation followed by receptor downregulation and sex hormone suppression.

3 cited references·5 researched benefits

Quick Answer

Buserelin (Suprefact) is a GnRH agonist used outside the US for prostate cancer, endometriosis, and IVF. Available as nasal spray, subcutaneous injection, and depot implant, it suppresses sex hormones through pituitary GnRH receptor downregulation after an initial flare. Though not FDA-approved, it is widely prescribed in Europe, Canada, and Australia with well-established efficacy comparable to other GnRH agonists.

Key Facts

Mechanism
Buserelin is a synthetic nonapeptide analog of GnRH with a D-serine(tBu) substitution at position 6 and an ethylamide at position 10, making it approximately 20-50 times more potent than native GnRH. It binds to pituitary GnRH receptors and initially stimulates LH and FSH release (the flare effect lasting 1-2 weeks). With continuous administration, GnRH receptors are downregulated and gonadotroph cells become desensitized, leading to profound suppression of gonadotropins and downstream sex steroids. Testosterone in men and estradiol in women fall to castrate/postmenopausal levels within 2-4 weeks. The intranasal formulation has approximately 2-3% bioavailability, while the subcutaneous route provides nearly complete absorption.
Research Status
approved
Half-Life
~1-1.5 hours
Molecular Formula
C₆₀H₈₆N₁₆O₁₃
Primary Use
Hormone Regulation
Table of Contents

Benefits

  • Effective androgen deprivation for advanced prostate cancer — achieves castrate testosterone levels comparable to orchiectomy in randomized trialsstrong
  • Reduces endometriosis-associated pain and lesion size — demonstrated efficacy in multiple European clinical studiesstrong
  • Pituitary downregulation for IVF — widely used in long-protocol IVF cycles to prevent premature LH surge and improve oocyte retrieval outcomesstrong
  • Multiple delivery routes available — intranasal, subcutaneous, and implant formulations offer flexibility for different clinical settingsstrong
  • Well-established safety profile with over 30 years of clinical use internationallystrong

Dosage Protocols

RouteDosage RangeFrequencyNotes
Subcutaneous injection (prostate cancer)500 mcg three times daily for first 7 days, then 200 mcg once daily (maintenance)Three times daily (induction), once daily (maintenance)Initial higher-dose loading phase to achieve rapid suppression. Antiandrogen cover (cyproterone acetate or bicalutamide) recommended during flare period.
Intranasal spray (prostate cancer)400 mcg (2 sprays) into each nostril three times daily (total 1,200 mcg/day)Three times dailyHigher intranasal doses required due to low nasal bioavailability (~2-3%). Avoid nasal decongestants within 30 minutes of administration.
Subcutaneous injection or intranasal (IVF)150-500 mcg/day subcutaneous, or 300-600 mcg/day intranasalDaily, starting mid-luteal phase (day 21)Used for pituitary downregulation in long GnRH agonist IVF protocols. Continued until hCG trigger for ovulation.
Subcutaneous implant6.3 mg or 9.45 mg implantEvery 2 or 3 monthsSuprefact Depot implant provides sustained release. Available in some European markets.

Medical disclaimer

Dosage information is provided for educational reference only. Always follow your prescriber's instructions and consult a qualified healthcare provider before starting any peptide protocol.

Side Effects

  • Hot flashes and sweating — experienced by 60-80% of patients, the most common effect of sex hormone suppressioncommon
  • Nasal irritation and rhinitis — with intranasal administration; occasional nosebleeds reportedcommon
  • Decreased libido and sexual dysfunction — expected consequence of castrate sex hormone levelscommon
  • Decreased bone mineral density — progressive loss with prolonged therapy; monitoring and protective measures recommendedserious
  • Testosterone flare in prostate cancer — initial 1-2 week worsening of symptoms; requires antiandrogen coverserious
  • Headache and mood disturbances — including depression and irritability, reported in 10-20% of patientscommon
  • Injection site reactions — pain, redness, and swelling with subcutaneous formulationscommon

Frequently Asked Questions

Why is buserelin not available in the United States?
Buserelin was never submitted for FDA approval in the United States because other GnRH agonists (leuprolide, goserelin, triptorelin) were already being developed and marketed there. The US market became dominated by leuprolide (Lupron) early on. Buserelin instead became widely established in European, Canadian, and Australian markets where it has been a standard treatment for decades. There is no clinical difference in efficacy compared to FDA-approved GnRH agonists.
How does buserelin compare to leuprolide (Lupron)?
Buserelin and leuprolide have equivalent efficacy for prostate cancer, endometriosis, and IVF applications. The main differences are in formulations and availability: buserelin offers an intranasal option and has a shorter half-life (1-1.5 hours vs. 3 hours for leuprolide), requiring more frequent dosing for the subcutaneous formulation. Leuprolide's long-acting depot injections (monthly to 6-monthly) offer more convenient dosing for prostate cancer patients. For IVF, buserelin is preferred in many European protocols due to decades of established use.
Does buserelin cause an initial testosterone flare?
Yes. Like all GnRH agonists, buserelin causes a transient increase in LH, FSH, and testosterone during the first 7-14 days of treatment. This flare can temporarily worsen prostate cancer symptoms including bone pain, urinary obstruction, and rarely spinal cord compression. Antiandrogen therapy (cyproterone acetate in Europe, bicalutamide or flutamide elsewhere) should be initiated before or simultaneously with buserelin to block the flare. The flare does not occur with GnRH antagonists like degarelix.
Can buserelin be used for endometriosis?
Yes, buserelin is approved in multiple countries for endometriosis treatment. It effectively suppresses estrogen production, causing endometriotic implants to become inactive and atrophy. Both intranasal and subcutaneous formulations are used, typically for 6 months. As with other GnRH agonists, add-back hormone therapy is recommended to mitigate bone loss and vasomotor symptoms. Efficacy is comparable to leuprolide and nafarelin in head-to-head studies.

References

  1. 1
    A potent long-acting agonist of luteinizing hormone-releasing hormone: buserelin and leuprolide comparative studies(1983)PubMed ↗
  2. 2
    Buserelin depot in the management of advanced prostate cancer: a European multicentre trial(1997)PubMed ↗
  3. 3
    GnRH agonists in assisted reproduction: buserelin versus leuprolide in IVF protocols(1996)PubMed ↗

Latest Research

Last updated: 2026-02-19