FDA-approved
Sexual & reproductive
Triptorelin
Triptorelin is an FDA-approved GnRH agonist given as a depot injection. Learn its approved uses, how it lowers testosterone, and what trials show.
- Reviewed by
- William Maish, MD MBA MPH, Clinical Product Lead
- Published
- October 5, 2026
- Last updated
- October 5, 2026
Key takeaway
Triptorelin (triptorelin pamoate, sold as Trelstar and Triptodur) is a synthetic decapeptide agonist of gonadotropin-releasing hormone given as a depot injection that suppresses testosterone. It is used for advanced prostate cancer in men and central precocious puberty in children, with depot forms covering one, three, or six months. It has been FDA-approved in the U.S. since 2000 and in a randomized comparison with leuprolide maintained castrate testosterone levels in men through nine months.
At a glance
| What it is | A GnRH (LHRH) receptor agonist peptide given as a long-acting depot |
| Approved for | Advanced prostate cancer (Trelstar) and central precocious puberty (Triptodur) |
| Key fact | In a randomized comparison it maintained castrate testosterone through nine months of treatment, comparable to leuprolide |
| Route | Intramuscular depot injection (1-, 3-, or 6-month) |
| Evidence strength | FDA approved |
What is triptorelin?
Triptorelin, known generically as triptorelin pamoate (also triptorelin acetate or embonate) and sold as Trelstar and Triptodur, is a synthetic ten-amino-acid analog of gonadotropin-releasing hormone (GnRH, also called LHRH). It is sometimes referred to in the research literature as D-Trp6-LHRH, after the substitution that distinguishes it. It is formulated as a microsphere depot that releases drug over weeks to months. Triptorelin was developed by Debiopharm and approved in the United States in 2000; it is marketed in Europe and elsewhere as Decapeptyl.
How does triptorelin work?
Triptorelin binds the GnRH receptor on the pituitary. A first dose transiently stimulates the gland, briefly raising luteinizing hormone, follicle-stimulating hormone, and testosterone, the flare. Because the depot then exposes the receptor continuously, the pituitary gonadotrophs downregulate and desensitize, and gonadotropin output falls, driving testosterone in men to castrate levels.
In advanced prostate cancer, removing testosterone starves hormone-sensitive tumor cells, which is the basis of treatment; in central precocious puberty, suppressing the premature hormone signal halts early sexual development. In a randomized comparison with leuprolide, triptorelin lowered testosterone slightly less quickly at first but maintained1 castrate testosterone equivalently through nine months. Depot formulations hold that suppression for one, three, or six months per injection, and the six-month Triptodur depot is dosed twice a year in children.
Is it FDA-approved?
Yes. The FDA has approved2 triptorelin as two products, first Trelstar and later Triptodur.
| Product | FDA approval | Approved for |
| Trelstar depot | 2000 | Advanced prostate cancer |
| Triptodur, the 6-month formulation | 2017 | Central precocious puberty |
It is available in 1-, 3-, and 6-month depot strengths.
What is triptorelin prescribed for?
Triptorelin is prescribed for the palliative treatment of advanced prostate cancer in men and for central precocious puberty in children. It is given by a healthcare professional as an intramuscular injection on the schedule matched to the depot strength.
What are the side effects?
According to the prescribing information, common side effects in men treated for prostate cancer include:
- Hot flashes
- Bone pain and headache
- Erectile dysfunction and testicular shrinkage
- Swelling or pain in the legs
Common side effects in children treated for central precocious puberty include:
- Injection-site reactions
- Vaginal bleeding early in treatment
- Hot flashes and headache
- Cough and respiratory infections
More serious considerations include:
- Initial testosterone surge and disease "flare" early in treatment
- Increased risk of hyperglycemia, diabetes, and cardiovascular events with long-term androgen deprivation
- Serious allergic reactions and severe skin reactions
- Convulsions
- In children, mood changes and increased pressure around the brain
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Sources: FDA prescribing information for Trelstar and Triptodur; a randomized comparison with leuprolide (Heyns et al., BJU International, 2003, DOI: 10.1046/j.1464-410x.2003.04308.x1), indexed on PubMed. This document is educational and does not constitute medical advice.