Evidence Grade A — Regulatory approved. 1200 published studies. 44 registered clinical trials.
Medically reviewed by a licensed medical professional
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Goserelin (sold as Zoladex) is a hormone-suppressing medication delivered as a tiny biodegradable implant injected under the skin of the abdomen, available in one-month and three-month formulations. It is used to treat prostate cancer, breast cancer in premenopausal women, and endometriosis by shutting down the body's production of sex hormones.
Goserelin is also known by these brand and alternate names:
1,200 published studies: 986 human, 33 animal, 47 in-vitro, 165 reviews
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.
Goserelin works through the same mechanism as leuprolide — it mimics the brain's natural GnRH signalling hormone but provides a constant rather than pulsed signal, ultimately shutting down sex hormone production. What distinguishes goserelin is its delivery method: it is embedded in a small biodegradable implant that slowly dissolves over one or three months, providing a steady release of medication without the need for repeated injections or reconstitution.
Goserelin has decades of clinical data across multiple conditions. Its implant delivery system is distinctive — there is no liquid injection or reconstitution required, and it does not need refrigeration, which can be a practical advantage in some clinical settings. The three-monthly formulation reduces the number of clinic visits required. Like all GnRH agonists, goserelin causes an initial hormone surge before suppression takes effect (typically two to four weeks), which in prostate cancer patients requires co-prescribing an anti-androgen to manage. Long-term hormone suppression carries risks including bone density loss, cardiovascular effects, and metabolic changes. In breast cancer, goserelin holds an important niche for suppressing ovarian function in premenopausal women with hormone-receptor-positive disease, often combined with aromatase inhibitors.
PeptideTrace tracks 44 registered clinical trials for Goserelin sourced from ClinicalTrials.gov.
Clinical Study on the Preservation of Ovarian Function in Patients With Aplastic Anemia Following Allogeneic Hematopoietic Stem Cell Transplantation Using Goserelin
A Study to Learn How Well a Combination of Darolutamide and Androgen Deprivation Therapy (ADT) Works as a Treatment Before Surgery for Men Who Have High-risk Localized Prostate Cancer.
PRIAPUS-PCa Study: Stereotactic Body Radiation Therapy (SBRT) and Androgen Deprivation Therapy (ADT) Impact on Sexual Function on Men With Unfavorable Intermediate Risk Prostate Cancer
Study on Triple Therapy Combined With HIFU for High-Tumor-Burden mHSPC
Pilot Study of Neoadjuvant Chemotherapy Combined With Immunotherapy and Multimodal Thermal Therapy for HER2-negative Breast Cancer
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Goserelin is a synthetic decapeptide (10 amino acids) GnRH agonist with D-Ser(tBu)6 and aza-Gly10 modifications. It is uniquely delivered as a biodegradable PLGA implant (Zoladex) injected subcutaneously in the anterior abdominal wall.
Goserelin's mechanism is identical to other GnRH agonists: continuous non-pulsatile stimulation of the GnRH receptor leads to an initial hormonal flare followed by receptor downregulation, resulting in sustained suppression of LH, FSH, and downstream sex steroids to castrate or postmenopausal levels. The PLGA matrix biodegrades over the dosing interval, providing controlled release.
Goserelin is marketed as Zoladex (AstraZeneca), available as 3.6 mg monthly and 10.8 mg 3-monthly subcutaneous implants. First approved December 1989. Indications include advanced prostate cancer, breast cancer (pre/perimenopausal), endometriosis, and endometrial thinning prior to ablation. Testosterone suppression to castrate range achieved in approximately 91% of patients over 336 days.
Carbetocin has not been approved by the FDA. It is registered in over 80 countries for prevention of uterine atony and excessive bleeding after caesarean delivery. A heat-stable formulation was added to the WHO Essential Medicines List in 2019. The CHAMPION trial (WHO, 2018; over 29,000 women) compared a heat-stable carbetocin formulation to oxytocin for preventing postpartum haemorrhage after vaginal delivery, and found it to be non-inferior. The heat-stable formulation addresses a significant limitation of oxytocin, which degrades in warm climates without refrigeration — a major concern in low-resource settings where postpartum haemorrhage causes the most deaths. Its regulatory status varies by jurisdiction.
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.
Triptorelin is marketed as Trelstar (approved 2000) for advanced prostate cancer, available as intramuscular depot injections in monthly (3.75 mg), three-monthly (11.25 mg), and six-monthly (22.5 mg) formulations. It is also widely used internationally for gender-affirming care and central precocious puberty. Triptorelin is one of the most commonly used GnRH agonists globally, though it faces the same competitive pressure as other agents in this class from newer oral GnRH antagonists like relugolix, which avoid the initial hormone flare and offer potential cardiovascular advantages. Clinical data demonstrate reliable testosterone suppression comparable to other GnRH agonists in this class.
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