10AA Approved Drug
Triptorelin
FDA/EMA-approved GnRH superagonist — 100× more potent than native GnRH, used for prostate cancer, endometriosis, precocious puberty, and gender-affirming puberty suppression.
In Plain English:
Triptorelin is a ten-amino-acid synthetic analogue of your body's gonadotropin-releasing hormone, with one strategic swap: D-tryptophan replaces glycine at position 6. That single change makes it 100× harder for enzymes to break down and 100× better at gripping the GnRH receptor. The result is paradoxical — it first triggers a massive surge of LH and FSH (the 'flare'), then over 2–4 weeks it overwhelms the pituitary so completely that hormone production collapses to castrate levels. Monthly depot injections then keep it there. Used medically for over 25 years to block hormones driving prostate tumours, endometriosis pain, and premature puberty.
Research Maturity
Approved Drug (2,458 results on PubMed for 'triptorelin' (verified 2026-05-04)+ Studies)
Focus
Hormone Modulation
Oncology
Reproductive Health
Origin
Emerged from Andrew Schally's Nobel Prize-winning GnRH programme (1977). The D-Trp6 substitution was developed systematically in the late 1970s at Tulane University. First European approval (Decapeptyl, Ipsen) in the 1980s for prostate cancer and endometriosis. FDA approved Trelstar Depot (Watson Pharma, 3.75 mg IM) in 2000 for advanced prostate cancer; extended to 11.25 mg (2001) and 22.5 mg / Triptodur (2017). EMA label substantially broader: includes central precocious puberty, uterine fibroids, female infertility, and gender dysphoria puberty suppression. Dutch gender clinic first used triptorelin for this purpose in 1998, establishing the foundational 'Dutch Protocol' later adopted by WPATH and the Endocrine Society.
Mechanism
Binds GnRH receptor type I on anterior pituitary gonadotrophs with ~100× higher affinity than native GnRH. Phase 1 (flare, days 1–14): activates Gq/11 → PLCβ → IP3/DAG → Ca2+-dependent exocytosis of stored LH and FSH. Testosterone may surge above 1,000 ng/dL in men. Phase 2 (desensitisation, days 14–28): continuous receptor occupation prevents recycling; >90% surface receptor density loss; LH/FSH secretion collapses. Phase 3 (sustained suppression, day 28+): testosterone falls to castrate range (<20 ng/dL in most patients); estrogen suppressed in women. Metabolism is local tissue proteolysis — not hepatic CYP450 — making drug interactions minimal. Depot PLGA microsphere formulation provides controlled release over 1, 3, or 6 months.
Outcome
Prostate cancer: 97.5% achieve testosterone castration (≤50 ng/dL) by day 29; PSA median decrease 97% at 6 months. Endometriosis: Cochrane review (>3,000 patients) confirms significant pain relief. CPP: mean 3.4 cm additional height gained vs. predicted final height in treated children. IVF trigger (0.1–0.2 mg SC): OHSS rate reduced to ~0% vs. 1–2% with hCG trigger. Gender-affirming puberty suppression: suppresses Tanner progression; improvements in depression, anxiety, and suicidality scores across 51 studies.
