{"id":"triptorelin","name":"Triptorelin","aliases":["Trelstar","Triptodur","Decapeptyl","triptorelin pamoate"],"url":"https://lyoresearch.com/compounds/triptorelin","class":{"id":"reproductive-hormones","name":"Reproductive and neuroendocrine hormones","url":"https://lyoresearch.com/classes/reproductive-hormones"},"summary":"Triptorelin is a synthetic ten-amino-acid analogue of gonadotropin-releasing hormone, approved since the 1980s and sold as Trelstar for advanced prostate cancer and Triptodur for central precocious puberty. Given continuously it shuts the reproductive axis down after an initial surge. Its grey-market reputation is the opposite use — a single low dose to restart testosterone production after anabolic steroids — and that rests on one published case report of one man, not on any trial.","overall_grade":"A","overall_grade_meaning":"established in humans","human_trials":"Approval programme; the grey-market use rests on 1 case report","regulatory_status":"Approved (Rx)","molecule":{"formula":"C64H82N18O13","molecular_weight":"1311.4","cas":"57773-63-4","pubchem_cid":25074470,"sequence":"[pGlu]HWSY[D-Trp]LRPG-NH2","sequence_note":"Matches the decapeptide structure given in the Trelstar label.","note":null},"pharmacokinetics":{"basis":"label","route":"Intramuscular depot injection","half_life":"About 6 minutes, 45 minutes and 3 hours in a three-compartment model","licensed_regimen":"Depot injection repeated every 4, 12 or 24 weeks depending on the strength used, for advanced prostate cancer; Triptodur is a 24-week depot for central precocious puberty","product":"Trelstar","source":{"title":"Trelstar prescribing information (DailyMed)","url":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=b1b84d62-a369-a4b7-5c41-dd1f553a18f3"}},"outcomes":[{"outcome":"Testosterone suppression in advanced prostate cancer","grade":"A","grade_meaning":"established in humans","effect_size":"large","adverse":false,"human_studies":"Approval programme; decades of use","evidence":"The licensed indication. Continuous GnRH receptor occupancy desensitises the pituitary, and after a transient surge testosterone falls to castrate levels. The Trelstar label carries three depot intervals for this use and the effect is the basis of forty years of androgen-deprivation therapy.","references":[{"citation":"Trelstar (triptorelin pamoate) prescribing information.","where":"DailyMed, read 29 Oct 2026","url":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=b1b84d62-a369-a4b7-5c41-dd1f553a18f3"}]},{"outcome":"Central precocious puberty","grade":"A","grade_meaning":"established in humans","effect_size":"large","adverse":false,"human_studies":"Approval programme","evidence":"Triptodur is approved for central precocious puberty in children aged two and above, as a single depot injection repeated every 24 weeks — the same axis shutdown used to halt premature puberty.","references":[{"citation":"Triptodur (triptorelin) prescribing information.","where":"DailyMed, read 29 Oct 2026","url":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=f41380e7-b830-432d-a5f5-a872932f107e"}]},{"outcome":"Restarting testosterone after anabolic steroids","grade":"D","grade_meaning":"no human evidence","effect_size":"not measurable","adverse":false,"human_studies":"1 case report (n=1)","evidence":"A 2010 Italian case report describes one man with hypogonadism after anabolic steroid use who was given a single 100 μg dose of triptorelin; testosterone was in the normal range within a month. One patient, no control, no replication in sixteen years. Forum protocols built on this report also ignore the dose relationship: the licensed depot products use the same molecule to switch the axis off.","references":[{"citation":"Pirola I, Cappelli C, Delbarba A, et al. Anabolic steroids purchased on the Internet as a cause of prolonged hypogonadotropic hypogonadism.","where":"Fertil Steril, 2010;94:2331–2332","url":"https://pubmed.ncbi.nlm.nih.gov/20416868/"}],"verbatim":{"text":"Within 1 month, the patient's serum testosterone was in the normal range, and he reported a return to normal energy and libido.","citation":"Pirola I, Cappelli C, Delbarba A, et al. Anabolic steroids purchased on the Internet as a cause of prolonged hypogonadotropic hypogonadism.","url":"https://pubmed.ncbi.nlm.nih.gov/20416868/"}},{"outcome":"Initial testosterone surge (\"flare\")","grade":"A","grade_meaning":"established in humans","effect_size":"moderate","adverse":true,"human_studies":"Approval programme","evidence":"The first days after a depot injection bring a rise in testosterone before suppression — clinically important in prostate cancer because it can transiently worsen symptoms, and the reason anti-androgen cover is used.","references":[{"citation":"Trelstar (triptorelin pamoate) prescribing information.","where":"DailyMed, read 29 Oct 2026","url":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=b1b84d62-a369-a4b7-5c41-dd1f553a18f3"}]}],"regions":[{"region":"European Union","status":"Approved, prescription-only","note":"Authorised nationally across member states (Decapeptyl and others) for prostate cancer, endometriosis, uterine fibroids, precocious puberty and in assisted reproduction."},{"region":"United States","status":"Approved, prescription-only","note":"Trelstar for advanced prostate cancer; Triptodur for central precocious puberty. Vials sold online for \"restart\" protocols are unapproved drugs."},{"region":"United Kingdom","status":"Licensed, prescription-only","note":"Decapeptyl SR licensed by the MHRA."},{"region":"Australia","status":"Registered, Schedule 4","note":"Diphereline / Decapeptyl registered on the ARTG."},{"region":"Canada","status":"Authorised, prescription-only","note":"Trelstar authorised with a Drug Identification Number."},{"region":"Sport (WADA)","status":"Prohibited for males at all times","note":"GnRH agonists are S2 (peptide hormones, growth factors and related substances) for male athletes."}],"faq":[{"q":"Does a single triptorelin shot restart testosterone after a steroid cycle?","a":"One published case report, of one man, says his testosterone normalised within a month of a single 100 μg dose. That is the entire evidence base, and post-cycle hypogonadism also resolves on its own. The same molecule in its licensed form is used to shut the axis down."},{"q":"Is triptorelin the same as leuprolide?","a":"Both are GnRH agonists from the same generation that suppress the axis through continuous receptor occupancy. They differ in the substituted residues and in which depot products are licensed where."},{"q":"Is triptorelin banned in sport?","a":"Yes, for male athletes — GnRH agonists sit in S2 of the Prohibited List, prohibited at all times."}],"references":[{"cite":"Trelstar (triptorelin pamoate) prescribing information.","where":"DailyMed, read 29 Oct 2026","url":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=b1b84d62-a369-a4b7-5c41-dd1f553a18f3","note":"Advanced prostate cancer; three depot intervals; pharmacokinetics and the decapeptide structure."},{"cite":"Triptodur (triptorelin) prescribing information.","where":"DailyMed, read 29 Oct 2026","url":"https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=f41380e7-b830-432d-a5f5-a872932f107e","note":"Central precocious puberty in children aged 2 and above; 24-week depot."},{"cite":"Pirola I, Cappelli C, Delbarba A, et al. Anabolic steroids purchased on the Internet as a cause of prolonged hypogonadotropic hypogonadism.","where":"Fertil Steril, 2010;94:2331–2332","url":"https://pubmed.ncbi.nlm.nih.gov/20416868/","note":"Case report, n=1. The origin of the \"triptorelin restart\" protocol."}],"last_reviewed":"2026-10-29","literature_searched_to":"2026-10-29","changelog":[{"date":"2026-10-29","note":"Initial publication. Grade A for the licensed uses; the grey-market restart row graded D on a single case report."}],"license":"CC BY 4.0 — cite as “LYO Research” with a link.","methodology":"https://lyoresearch.com/methodology"}