Injectable GnRH analog that suppresses testosterone or estrogens. Used in prostate cancer, premenopausal breast cancer, endometriosis, fibroids, IVF, and central precocious puberty.
FDA (US): Approved (2000, Trelstar) for palliative treatment of advanced prostate cancer; approved (2017, Triptodur) for central precocious puberty in children aged 2 years and older.
EMA (EU): No centralized authorization; authorized nationally in the EU. In Spain (AEMPS, Decapeptyl) for prostate cancer, hormone-sensitive early breast cancer in premenopausal women (with tamoxifen or an aromatase inhibitor), endometriosis, uterine fibroids, IVF, and central precocious puberty.
Dose
Prostate cancer: 3.75 mg intramuscularly every 4 weeks, 11.25 mg every 12 weeks, or 22.5 mg every 24 weeks (FDA Trelstar label). Endometriosis and fibroids: 3.75 mg every 4 weeks for 4–6 months; breast cancer: 3.75 mg every 4 weeks for up to 5 years (CIMA-AEMPS label, Decapeptyl).
Safety
Hot flashes (very common in women, common in men), lower libido, bone density loss with risk of osteoporosis (in women ~1% per month), depression, hypertension, hyperglycemia, and injection-site reactions. May prolong the QT interval. At the start it may transiently worsen symptoms because of the hormonal surge. Contraindicated in pregnancy and breastfeeding. Requires a prescription and medical follow-up.
Interactions
Caution with drugs that prolong the QT interval (antiarrhythmics such as amiodarone or sotalol, methadone, moxifloxacin, antipsychotics). Caution with anticoagulants because of the intramuscular injection.
Differences between women and men
Different indications by sex: in men, prostate cancer; in women, premenopausal breast cancer, endometriosis, fibroids, and IVF. According to the Spanish label, hot flashes are very common in women and common in men. Contraindicated in pregnancy and breastfeeding.
Effect by goal · level of evidence
Hormonal castration in advanced prostate cancer
reducesHighclinical trial (A)in people
97.5% castration
Open-label phase 3 trial in 120 men with advanced prostate cancer: with the 6-month formulation, 97.5% reached castrate testosterone levels by day 29 and 93% maintained them through month 12. The most common adverse effect was hot flashes (71.7%).
Relapse in premenopausal breast cancer (ovarian suppression)
reducesHighRCT (AA)in people
HR 0.72
TEXT and SOFT trials (4,690 premenopausal women; ovarian suppression mainly with triptorelin): exemestane plus ovarian suppression achieved 91.1% disease-free survival at 5 years versus 87.3% with tamoxifen plus suppression (HR 0.72).
Continuously stimulates the GnRH receptor of the pituitary gland. After an initial surge, the pituitary becomes desensitized and stops releasing LH and FSH. As a result, testosterone falls in men and estrogen in women, which slows hormone-dependent tumors and endometriosis.
What the evidence says
In people
Hormonal castration in advanced prostate cancer. Open-label phase 3 trial in 120 men with advanced prostate cancer: with the 6-month formulation, 97.5% reached castration-level testosterone on day 29 and 93% maintained it through month 12. The most common adverse effect was hot flashes (71.7%). PubMed 19888782
Relapse in premenopausal breast cancer (ovarian suppression). TEXT and SOFT trials (4,690 premenopausal women; ovarian suppression mostly with triptorelin): exemestane plus ovarian suppression achieved 91.1% disease-free survival at 5 years vs 87.3% with tamoxifen plus suppression (HR 0.72). PubMed 24881463