Zoladex
Evidence Grade A — Regulatory approved. 1193 published studies. 43 registered clinical trials.
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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.
1,193 published studies: 984 human, 33 animal, 47 in-vitro, 164 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.
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
Artificial Intelligence Driven Personalisation of Radiotherapy and Concomitant Androgen Deprivation Therapy for Prostate Cancer Patients (the HypoPro Trial)
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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.
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.
Elagolix is marketed as Orilissa for endometriosis pain (approved July 2018) and as a component of Oriahnn for heavy menstrual bleeding from uterine fibroids (approved May 2020). Oriahnn combines elagolix with low-dose hormone add-back therapy to mitigate bone density loss. Clinical trials showed that the higher dose reduced menstrual pain in approximately 76% of patients and non-menstrual pelvic pain in about 55% at six months. The main limitation is bone density loss with prolonged use, which the add-back therapy in Oriahnn helps address. As an oral tablet taken daily, it offers a fundamentally different experience from injectable or implanted hormone treatments, though it requires consistent daily dosing. It is important to note that elagolix is not a peptide — it is included in this database because it targets the same GnRH pathway as peptide-based treatments.
