Buserelin
A GnRH agonist used across Europe for decades and never approved in the United States
Buserelin shuts down the pituitary's sex-hormone signalling by overstimulating it. Used in IVF, endometriosis and prostate cancer in Europe since the 1980s, often as a nasal spray, it has no US approval.
What is it?
GnRH is released in pulses, and the pituitary answers pulses. Give a GnRH agonist continuously and the pituitary stops answering: LH and FSH fall, and with them oestrogen or testosterone. That shutdown is the point in IVF, in endometriosis and in hormone-sensitive prostate cancer.
Buserelin's clinical record is European and mostly from the 1990s, which shapes this entry: the comparisons are with goserelin, the questions are about dose and route, and the endpoints are pregnancy rates and symptom scores.
The route difference matters to tolerability. In a direct comparison for IVF down-regulation, pregnancy rates were similar for intranasal buserelin and subcutaneous goserelin, while the buserelin group reported significantly more tiredness, depression, headache and abdominal pain. In endometriosis, nasal buserelin relieved pain about as well as gestrinone or dienogest, but tolerance was poor and dienogest caused less bone loss.
In prostate cancer it did what castration does. Nasal buserelin matched orchiectomy for testosterone suppression and survival over a year, and a single 9.45 mg implant held testosterone at castrate levels for about seven months before it recovered. Attempts beyond hormone-sensitive tumours failed, as in pancreatic cancer.
It is not approved in the United States, which is the single most important fact for a reader here. DailyMed lists only a bulk buserelin acetate powder from a chemical supplier, not a drug label.
Mechanism of Action
Buserelin is a GnRH agonist: given continuously, it first stimulates and then shuts down the pituitary's release of LH and FSH.
Pituitary desensitisation
Continuous exposure stops LH and FSH release, lowering oestrogen or testosterone to castrate levels.
Nasal or implant
Given as a nasal spray or as a long-acting implant; one 9.45 mg implant held testosterone down for about seven months.
Short-acting flare
A single dose triggers an LH surge, which is why it has also been used to trigger ovulation and support the luteal phase.
Published Research
These are the studies in people, read from their PubMed abstracts: comparisons for IVF down-regulation, an endometriosis study and dosing work.
Nasal buserelin against injected goserelin
In IVF down-regulation, pregnancies occurred in 22.4% with goserelin and 24.0% with buserelin. The goserelin group needed more HMG ampoules for follicular maturation (27.9 against 24.6, p < 0.05), while the buserelin group reported significantly more tiredness, depression, headache and abdominal pain.
A single injection against daily nasal dosing
In 142 women undergoing IVF, a single injection of goserelin was compared with buserelin for pituitary down-regulation. Age and gonadotrophin use were similar, while the proportion down-regulated by two weeks and the pregnancy rate per embryo transfer were significantly higher in the goserelin group, with similar miscarriage rates.
In endometriosis
A German multicentre study of buserelin for endometriosis reported symptom frequencies before and after therapy: dysmenorrhoea 65.0% to 11.2%, pelvic pain 48.2% to 14.1%, and pain on examination 40.0% to 9.7%.
What it does to the pulse
In women with endometriosis given 300 to 900 µg a day for six months, buserelin suppressed ovulation in all; at 900 µg oestradiol fell below 30 pg/mL and LH pulse amplitude declined while LHRH pulses were unchanged.
How much to give
A short published comment on buserelin dosage in IVF; PubMed carries no abstract, so it adds no measured result.
With tamoxifen in premenopausal breast cancer
In premenopausal women with metastatic breast cancer, buserelin plus tamoxifen gave longer progression-free survival (9.7 months against 6.3 and 5.6) and overall survival (3.7 years against 2.5 and 2.9) than either alone.
As an ovulation trigger
In antagonist IVF cycles, a buserelin trigger yielded more mature eggs than hCG, but implantation (3 of 89 against 33 of 97) and clinical pregnancy (6% against 36%) were far lower, with 79% early loss.
Against dienogest in endometriosis
In 271 women treated for 24 weeks, oral dienogest matched intranasal buserelin 900 µg a day on most pain scores, with more irregular bleeding but fewer hot flushes and significantly less bone loss.
Endometriosis five years on
Intranasal buserelin and gestrinone had similar good or excellent efficacy (78% and 74%), but tolerance was rated good in none on buserelin; after five years, success was about a third in each group.
A three-month implant in prostate cancer
In 21 men, a single 9.45 mg implant kept testosterone at castrate levels for a mean of 224 days; testosterone recovered by 8 to 12 months, and 90% had hot flushes at 12 weeks.
Against orchiectomy and oestrogens
In 140 men with metastatic prostate cancer, intranasal buserelin, orchiectomy and oestrogens did not differ in testosterone suppression or survival at one year; buserelin and orchiectomy improved performance status, oestrogens did not.
Pancreatic cancer: no effect
In 9 patients with unresectable pancreatic adenocarcinoma, buserelin combined with tamoxifen or cyproterone acetate failed: disease progressed in all.
Nasal buserelin as luteal support
In a 24-patient feasibility study after insemination, daily intranasal buserelin through the luteal phase gave higher day-14 progesterone than hCG, with one clinical pregnancy among the buserelin groups.
Dosing Data
There is no US-approved dose. Trials used intranasal 300 to 900 µg a day for endometriosis and a 9.45 mg implant every three months for prostate cancer.
Educational information, not medical advice. Each dose above is tagged with its source: an approved label, a published human study, animal data, or amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
Side Effects & Contraindications
Reported Side Effects
From the comparisons above; these are the effects of shutting down sex hormones.
Contraindications & Cautions
Not approved in the United States.
Legal Status
Licensed in Europe, not in the United States.
Frequently Asked Questions
?What is buserelin used for?
Pituitary down-regulation in IVF, endometriosis, and hormone-sensitive prostate cancer, in countries where it is licensed.
?Is it available in the United States?
No. It has no FDA approval. Goserelin and leuprolide are the approved GnRH agonists there.
?Does the nasal spray work as well as an injection?
In IVF comparisons, pregnancy rates were similar, but one study found a higher proportion down-regulated by two weeks with injected goserelin, and nasal buserelin caused more tiredness, depression and headache.
?Why does a stimulator shut hormones down?
The pituitary responds to pulses of GnRH. Continuous stimulation desensitises it, so LH and FSH fall.
?What are the downsides of long use?
Those of low oestrogen or testosterone. In endometriosis, buserelin caused more hot flushes and more bone loss than dienogest over 24 weeks, and tolerance was poor in a five-year follow-up. In men on an implant, 90% had hot flushes at 12 weeks, easing as testosterone recovered.
References
- [pubmed] Tapanainen J, et al. "Subcutaneous goserelin versus intranasal buserelin for pituitary down-regulation in patients undergoing IVF: a randomized comparative study." Hum Reprod, 1993;8(12):2052-5. PMID: 8150902.
- [pubmed] Oyesanya OA, et al. "Pituitary down-regulation prior to in-vitro fertilization and embryo transfer: a comparison between a single dose of Zoladex depot and multiple daily doses of Suprefact." Hum Reprod, 1995;10(5):1042-4. PMID: 7657737.
- [pubmed] Schindler AE, et al. "[Treatment of endometriosis with the GnRH agonist buserelin (Suprecur): a multicenter study]." Geburtshilfe Frauenheilkd, 1994;54(10):569-73. PMID: 8001754.
- [pubmed] Okuda K, et al. "Effect of LHRH agonist (buserelin) on pulsatile secretion of LHRH and LH." Nihon Sanka Fujinka Gakkai Zasshi, 1988;40(12):1889-93. PMID: 3145318.
- [pubmed] Yu N. "Dosage of buserelin." J Reprod Med, 2000;45(11):964-5. PMID: 11127117.
- [other] Suprefact (buserelin acetate) Product Monograph. Sanofi-Aventis Canada.
- [other] Suprefact Summary of Product Characteristics. Electronic Medicines Compendium (eMC), United Kingdom.
- [review] Del Moral-Sanchez JM, et al. "Worldwide Availability of GnRH Agonists in Oncology and Reproductive Medicine." Pharmaceutics.
- [clinical-trial] Klijn JG, et al. "Combined treatment with buserelin and tamoxifen in premenopausal metastatic breast cancer: a randomized study." J Natl Cancer Inst, 2000;92(11):903-11. PMID: 10841825.
- [clinical-trial] Humaidan P, et al. "GnRH agonist (buserelin) or hCG for ovulation induction in GnRH antagonist IVF/ICSI cycles: a prospective randomized study." Hum Reprod, 2005;20(5):1213-20. PMID: 15760966.
- [pubmed] Harada T, et al. "Dienogest is as effective as intranasal buserelin acetate for the relief of pain symptoms associated with endometriosis--a randomized, double-blind, multicenter, controlled trial." Fertil Steril, 2009;91(3):675-81. PMID: 18653184.
- [pubmed] Nieto A, et al. "Long-term follow-up of endometriosis after two different therapies (Gestrinone and Buserelin)." Clin Exp Obstet Gynecol, 1996;23(4):198-204. PMID: 9001779.
- [pubmed] Pettersson B, et al. "Duration of testosterone suppression after a 9.45 mg implant of the GnRH-analogue buserelin in patients with localised carcinoma of the prostate a 12-month follow-up study." Eur Urol, 2006;50(3):483-9. PMID: 16626856.
- [pubmed] Bruun E, et al. "The effect of Buserelin versus conventional antiandrogenic treatment in patients with T2-4NXM1 prostatic cancer. A prospective, randomized multicentre phase III trial. The "Danish Buserelin Study Group"." Scand J Urol Nephrol, 1996;30(4):291-7. PMID: 8908651.
- [pubmed] Swarovsky B, et al. "Tamoxifen or cyproterone acetate in combination with buserelin are ineffective in patients with pancreatic adenocarcinoma." Oncology, 1993;50(4):226-9. PMID: 8497375.
- [pubmed] Pirard C, et al. "GnRH agonist as novel luteal support: results of a randomized, parallel group, feasibility study using intranasal administration of buserelin." Hum Reprod, 2005;20(7):1798-804. PMID: 15890740.
Sources & Citations
Studies were read from their PubMed abstracts; no US label exists. Read October 6, 2026.
Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Talk to a licensed clinician about your own situation.