Triptorelin Evidence Guide
Triptorelin (Trelstar) is FDA-approved for prostate cancer androgen deprivation and gender-affirming hormone therapy, with multiple Phase 3 RCTs supporting both indications. As a GnRH agonist, it produces reliable castrate-level testosterone suppression with a well-characterized adverse effect profile. For research into GnRH agonist pharmacology or testosterone suppression, it is a validated reference compound.
Our Take
Triptorelin (Trelstar) is FDA-approved for prostate cancer androgen deprivation and gender-affirming hormone therapy, with multiple Phase 3 RCTs supporting both indications. As a GnRH agonist, it produces reliable castrate-level testosterone suppression with a well-characterized adverse effect profile. For research into GnRH agonist pharmacology or testosterone suppression, it is a validated reference compound.
- Evidence context
- Prostate cancer androgen deprivation, gender-affirming hormone therapy, GnRH agonist pharmacology
- Evidence grade
- Level A
- Confidence
- High
- Reference context
- Regulatory label reference: 3.75mg IM monthly or 11.25mg IM every 3 months
Benefits and Evidence
- Prostate Cancer Control: Level A, includes human evidence - Triptorelin achieves castrate testosterone levels in >95% of advanced prostate cancer patients. Multiple large RCTs demonstrate disease control equivalent to surgical castration with reversibility.
- Endometriosis Symptom Relief: Level A, includes human evidence - Significant reduction in endometriosis-related pain, dysmenorrhea, and endometrial implant size. Efficacy comparable to other GnRH agonists with estrogen suppression.
- Central Precocious Puberty Arrest: Level A, includes human evidence - Effectively halts premature pubertal development and preserves adult height potential. Standard of care for central precocious puberty in children.
Side Effects and Warnings
- Hot flashes
- Initial tumor flare (prostate cancer)
- Decreased libido and erectile dysfunction
- Bone mineral density loss with prolonged use
- Injection site reactions
- Mood changes and depression
- Fatigue
- Initial testosterone flare can worsen prostate cancer symptoms - consider anti-androgen cover for first 2-4 weeks
Research Dosage References
- <strong>Intramuscular depot</strong> - 3.75 mg (monthly) or 11.25 mg (3-month) or 22.5 mg (6-month) - Monthly, quarterly, or semi-annually - Depot formulation provides sustained release. Prostate cancer: typically 3-month or 6-month depot. Endometriosis: usually limited to 6 months with add-back therapy.
- <strong>Subcutaneous</strong> - 0.1 mg/day - Daily (short protocol for IVF) - Used in some IVF stimulation protocols. Less common than depot formulations.
Mechanism of Action
Triptorelin acts through GnRH receptor desensitization: 1. Initial agonism: Binds GnRH receptors on pituitary gonadotropes with high affinity, initially stimulating LH and FSH release ("flare" effect lasting 1-2 weeks). 2. Receptor downregulation: Continuous receptor occupation leads to internalization and downregulation of GnRH receptors on the cell surface. 3. Gonadotropin suppression: Desensitized pituitary stops producing LH and FSH, leading to profound suppression of downstream sex hormones. 4. Chemical castration: Testosterone (males) or estrogen (females) falls to castrate/menopausal levels, achieving the therapeutic goal in hormone-dependent conditions.
Legal Status
FDA-approved prescription medication (Trelstar). Available by prescription only. Not a controlled substance.
Primary Sources
- Triptorelin 6-month depot for the treatment of advanced prostate cancer. European Urology, 2009.
- GnRH agonists in the treatment of endometriosis: a Cochrane review. Cochrane Database of Systematic Reviews, 2010.
- Triptorelin for central precocious puberty: efficacy and safety. Journal of Clinical Endocrinology & Metabolism, 2004.
Quick Answers
Where is the strongest evidence for Triptorelin?
Triptorelin (Trelstar) is FDA-approved for prostate cancer androgen deprivation and gender-affirming hormone therapy, with multiple Phase 3 RCTs supporting both indications. As a GnRH agonist, it produces reliable castrate-level testosterone suppression with a well-characterized adverse effect profile. For research into GnRH agonist pharmacology or testosterone suppression, it is a validated reference compound. Evidence context: Prostate cancer androgen deprivation, gender-affirming hormone therapy, GnRH agonist pharmacology.
What are the main side effects of Triptorelin?
Triptorelin side effects and warning signals include Hot flashes, Initial tumor flare (prostate cancer), Decreased libido and erectile dysfunction, Bone mineral density loss with prolonged use, and Injection site reactions.
What evidence level is Triptorelin?
Triptorelin is rated Level A; the listed research status is FDA Approved.