Factrel, Lutrepulse, GnRH
Evidence Grade B — Strong clinical evidence. 292 published studies, 116 human. 1000 registered clinical trials.
Gonadorelin is the natural form of GnRH — the brain hormone that controls reproductive function. Unlike the modified synthetic versions (leuprolide, goserelin, etc.) that suppress hormones, gonadorelin delivered in pulses can actually restore normal hormone production. Previously available as approved products (Factrel and Lutrepulse), all formulations have been voluntarily discontinued, and it is now available only from compounding pharmacies.
292 published studies: 116 human, 125 animal, 17 in-vitro, 28 reviews
Gonadorelin was previously marketed as Factrel (for diagnostic testing of pituitary function) and Lutrepulse (pulsatile GnRH pump for treating infertility caused by hypothalamic dysfunction). Both have been voluntarily discontinued due to low commercial demand and the complexity of pulsatile administration.
Research suggests that pulsatile gonadorelin remains one of the most physiologically appropriate treatments for certain types of infertility where the underlying problem is insufficient GnRH production in the brain. However, the practical challenges of wearing a pump that delivers pulses every 90 minutes, combined with the availability of simpler alternatives, have made it commercially unviable. It continues to be used in research settings studying reproductive endocrinology and GnRH receptor function.
Gonadorelin is the body's own signalling hormone that tells the pituitary gland to release the hormones (LH and FSH) that drive testosterone and oestrogen production. When given in pulses that mimic the brain's natural 90-minute rhythm, it can actually restore normal hormone function — the opposite of what synthetic GnRH agonists do. When given continuously, however, it causes the same shutdown effect as synthetic agonists, though it is far less potent and shorter-acting because the body breaks it down within minutes.
Research suggests pulsatile gonadorelin remains one of the most physiologically appropriate treatments for infertility caused by insufficient GnRH production — it restores the brain's natural signalling rather than overriding it. However, the practical challenges of wearing a pump that delivers pulses every 90 minutes, combined with simpler alternatives, made it commercially unviable. Compounding pharmacies have filled the gap, particularly for off-label use during testosterone therapy to maintain natural hormone production. No controlled clinical trials exist for these compounding pharmacy use cases. The distinction between pulsatile (stimulatory) and continuous (suppressive) administration is a key pharmacological concept for this compound.
Goserelin, Flutamine, and Radiation Therapy in Treating Patients With Locally Advanced Prostate Cancer
Human Menopausal Gonadotropin (HMG) vs Recombinant Follicle Stimulating Hormone (rFSH) in Gonadotropin Releasing Hormone (GnRH) Antagonist Cycles
Antineoplaston Therapy in Treating Patients With Stage III or Stage IV Prostate Cancer
A Phase II Randomized Open Label Study of KLH-2109 in Patients With Endometriosis
GnRH Agonist and Antagonists in an Oocyte Donation Program
Health Canada Market Authorisation
The information on this page is provided for educational and research reference purposes only. This is not medical advice. Always consult a qualified healthcare professional before making any health-related decisions.
Histrelin is available as Supprelin LA for central precocious puberty (approved 2007). The Vantas implant for prostate cancer was approved in 2004 but discontinued in 2021. The implant requires a minor surgical procedure for insertion and removal/replacement each year. Supprelin LA's main clinical advantage is its 12-month duration — the longest of any GnRH agonist — which is particularly valuable in paediatric patients where treatment compliance over years is important. Clinical studies demonstrated effective suppression of puberty markers in over 97% of patients. The implant has also seen significant off-label use in gender-affirming care as a puberty blocker, where its annual dosing schedule offers practical benefits for adolescent patients and their families.
Goserelin is marketed as Zoladex by AstraZeneca, available as 3.6 mg monthly and 10.8 mg three-monthly subcutaneous implants. First approved in 1989, it is used in advanced prostate cancer, premenopausal breast cancer, endometriosis, and for thinning the uterine lining before surgical procedures. Goserelin achieves castrate-level testosterone suppression (below 50 ng/dL) within two to four weeks. Its unique implant delivery system means there is no liquid injection, reconstitution, or refrigeration required — a practical advantage in some clinical settings. Like all GnRH agonists, it causes an initial hormone flare before suppression takes effect. Goserelin holds an important niche in breast cancer treatment, where it is used to suppress ovarian function in premenopausal women with hormone-receptor-positive disease, often in combination with aromatase inhibitors.
Nafarelin is marketed as Synarel (approved 1990) for endometriosis and central precocious puberty. It requires administration as one spray in each nostril twice daily — a higher frequency than injectable alternatives but avoids needles entirely, which can be a significant advantage for some patients, particularly children. Clinical trials showed symptom improvement in 75–92% of endometriosis patients. However, absorption can be affected by nasal congestion or concurrent use of nasal decongestants, which can be a practical limitation. As with all GnRH agonists, prolonged use leads to bone density loss, and treatment for endometriosis is typically limited to six months. Nafarelin occupies a niche for patients who prefer non-injectable hormone suppression, though it has become less commonly prescribed as longer-acting depot injections and oral alternatives have become available.
