Triptorelin
Triptorelin (GnRH Analog)
Synthetic GnRH Analog for Hormonal Health
What is Triptorelin?
Triptorelin is a synthetic decapeptide analog of gonadotropin-releasing hormone (GnRH), a hypothalamic hormone responsible for stimulating the pituitary gland to release luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Under physiological conditions, GnRH is released in pulses; triptorelin's continuous or depot administration disrupts this pulsatile pattern and produces a paradoxical suppression of gonadotropin secretion after an initial stimulatory flare.
Clinically, triptorelin is FDA-approved under the brand name Trelstar for the palliative treatment of advanced prostate cancer, where it reduces testosterone to castrate levels to slow tumor progression. It is also used off-label in the treatment of precocious puberty, endometriosis, uterine fibroids, and as part of in vitro fertilization protocols. Within research and sports performance circles, triptorelin has attracted attention as a post-cycle therapy (PCT) agent for restoring hypothalamic-pituitary-gonadal (HPG) axis function following exogenous androgen use.
The biphasic pharmacological response is central to understanding both its clinical utility and its PCT application. Within the first one to two weeks of a single low-dose injection, triptorelin causes a transient surge in LH and FSH (the flare effect), which transiently elevates testosterone. Following this initial stimulation, continuous receptor occupancy desensitizes pituitary GnRH receptors, leading to suppression. A single low dose (100 mcg) in the PCT context is intended to leverage only the flare phase to restart endogenous LH and testosterone production without crossing into suppression territory.
At depot doses used in oncology (3.75 mg, 11.25 mg, or 22.5 mg delivered monthly, quarterly, or semi-annually), triptorelin reliably suppresses testosterone to castrate range. At the micro-doses explored in PCT research (around 100 mcg), the intent is the opposite: to transiently stimulate LH and FSH secretion and accelerate HPG axis recovery. The margin between these two outcomes is narrow and requires precise dosing.
Research Supply
Source high-purity Triptorelin for your research
Dosage Guide
Route: Intramuscular (depot) or subcutaneous (investigational PCT use)
Dosing Schedule
| Period | Dose |
|---|---|
| Trelstar 3.75 mg (oncology) | 3.75 mg IM every 4 weeks |
| Trelstar 11.25 mg (oncology) | 11.25 mg IM every 12 weeks |
| Trelstar 22.5 mg (oncology) | 22.5 mg IM every 24 weeks |
| Investigational PCT (single administration) | 100 mcg subcutaneous; may repeat after 30 days if testosterone has not returned to reference range |
Reconstitution
Injection Volumes
| Dose | Volume | Syringe Units |
|---|
Administration Tips
- Triptorelin acetate for research use is supplied as lyophilized powder; reconstitute with bacteriostatic water to desired concentration
- Maintain cold chain storage at 2-8 degrees Celsius
- Do not exceed 100 mcg in a single PCT administration
- Administer after cessation of exogenous testosterone or anabolic steroids in PCT context
- The margin between PCT-stimulatory and suppressive dosing is narrow; precise dosing is critical
Risks & Side Effects
Commonly Reported
Serious Risks
Severe hypersensitivity or anaphylaxis
Rare but reported hypersensitivity reactions to GnRH agonist class compounds.
Tumor flare in prostate cancer
Testosterone surge in first 1-2 weeks may transiently worsen symptoms; use antiandrogens concurrently for 2-4 weeks at initiation.
Pituitary apoplexy
Rare; reported with GnRH agonist class.
Spinal cord compression
In patients with vertebral metastases from tumor flare, spinal cord compression can occur.
Prolonged hypogonadism
Overdose can cause persistent HPG suppression rather than recovery, resulting in prolonged hypogonadism.
Bone density loss
Osteoporosis risk with long-term castrate-range dosing.
Contraindications
- Women who are pregnant or may become pregnant (triptorelin can harm the fetus)
- Hypersensitivity to GnRH, GnRH agonist analogs, or any component of the formulation
- Undiagnosed vaginal bleeding
- Use as PCT in women (not appropriate; designed for male HPG axis recovery)
- Pre-existing severe osteoporosis (long-term use contraindicated without bone protection)
Frequently Asked Questions
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Experts Covering Triptorelin
LEGAL DISCLAIMER
The information provided on this page is for educational and informational purposes only and is not intended as medical advice. Triptorelin is FDA-approved only for palliative treatment of advanced prostate cancer; all other uses described here are investigational or off-label. Always consult with a qualified healthcare professional before starting any peptide therapy. Individual results may vary. Peptides Institute is not responsible for any adverse effects resulting from the use of information provided on this site.