From the Guidelines
Gonadotropin-Releasing Hormone Agonists (GnRH-a) are primarily indicated for hormone-dependent conditions, and the most recent evidence suggests that for prostate cancer, goserelin 3.6 mg monthly or 10.8 mg every three months is a common dosing regimen, with a recommended duration of 4-6 months for salvage radiotherapy, and up to 18-24 months for patients with high-risk features 1.
Indications and Dosing Regimens
The indications for GnRH-a therapy include:
- Endometriosis
- Uterine fibroids
- Precocious puberty
- Prostate cancer
- Fertility treatment protocols Common GnRH-a medications include:
- Leuprolide (Lupron)
- Goserelin (Zoladex)
- Nafarelin (Synarel)
- Triptorelin (Trelstar) For prostate cancer, the dosing regimen is typically goserelin 3.6 mg monthly or 10.8 mg every three months, with a recommended duration of 4-6 months for salvage radiotherapy, and up to 18-24 months for patients with high-risk features 1.
Mechanism of Action and Side Effects
GnRH-a medications work by initially stimulating gonadotropin release, followed by downregulation of pituitary receptors, leading to suppression of sex hormones. Side effects include:
- Menopausal symptoms
- Bone mineral density loss
- Initial flare of symptoms Add-back therapy with low-dose hormones is often used for longer treatment courses to minimize side effects while maintaining efficacy.
Clinical Recommendations
The most recent evidence suggests that for prostate cancer, GnRH-a therapy should be used in conjunction with salvage radiotherapy, with a recommended duration of 4-6 months, and up to 18-24 months for patients with high-risk features 1. Additionally, temporary ovarian suppression with a GnRHa during chemotherapy should be considered a standard option for ovarian function preservation in premenopausal breast cancer patients undergoing (neo)adjuvant systemic cytotoxic therapy 1.
From the FDA Drug Label
TRELSTAR is a gonadotropin releasing hormone (GnRH) agonist indicated for the treatment of advanced prostate cancer. TRELSTAR is administered as a single intramuscular injection in either buttock. 3.75 mg every 4 weeks. 11.25 mg every 12 weeks. 22.5 mg every 24 weeks.
The indications and dosing regimens for Gonadotropin-Releasing Hormone Agonist (GnRH-a) therapy with TRELSTAR are:
- Indication: Treatment of advanced prostate cancer
- Dosing regimens:
- 3.75 mg every 4 weeks
- 11.25 mg every 12 weeks
- 22.5 mg every 24 weeks 2
From the Research
Indications for Gonadotropin-Releasing Hormone Agonist (GnRH-a) Therapy
- Advanced prostate cancer: GnRH-a is used as a form of androgen deprivation therapy (ADT) to reduce testosterone levels and slow the growth of prostate cancer cells 3, 4, 5, 6
- Endometriosis: GnRH-a can help reduce the symptoms of endometriosis by decreasing estrogen levels 4
- Precocious puberty: GnRH-a is used to delay premature puberty in children 4, 7
- Uterine fibroids: GnRH-a may be used to reduce the size of uterine fibroids and alleviate symptoms 4
- Breast cancer: GnRH-a can be used as part of hormone therapy for breast cancer 4
- Polycystic ovarian disease: GnRH-a may be used to regulate menstrual cycles and improve fertility in women with polycystic ovarian disease 4
Dosing Regimens for GnRH-a Therapy
- The dosing regimen for GnRH-a therapy varies depending on the specific indication and the individual patient's needs 3, 5
- For advanced prostate cancer, GnRH-a is typically administered via injection every 1-3 months 3, 5
- For endometriosis and precocious puberty, GnRH-a may be administered via injection or nasal spray, with dosing regimens varying depending on the specific product and individual patient needs 4, 7
Comparison of Different GnRH-a Products
- Several studies have compared the efficacy and safety of different GnRH-a products, including goserelin, leuprolide, and triptorelin 3, 5, 7
- These studies have generally found that the different GnRH-a products have similar efficacy and safety profiles, although some differences in terms of testosterone suppression and side effects have been noted 3, 5, 7
- The choice of GnRH-a product may depend on individual patient factors, such as the specific indication, medical history, and personal preferences 3, 5, 7