Gestrinone (Dimetrose, Nemestran)
13β-ethyl-17α-ethynyl-19-nor-androsta-triene derivative. Roussel-Uclaf 1986 endometriosis Rx (Dimetrose in Europe, Nemestran globally). Anti-progestin/progestin mixed activity + weak androgen. Bodybuilding context rare; UGL sometimes markets as SARM-like – true anabolic activity weak.
WHAT IS GESTRINONE (DIMETROSE, NEMESTRAN)?
Detailed overview
Gestrinone (Dimetrose, Nemestran, R-2323) is a 19-nor steroid derivative (13β-ethyl-17α-ethynyl-gon-4,9,11-triene-17β-ol-3-one), developed by Roussel-Uclaf (France) in the 1980s for endometriosis treatment – EMA-level clinical introduction in 1986 in Europe (Tamaya 1986 PMID 3719842 Phase II + Coutinho 1991 PMID 1929670 large randomized trial). Mechanism is complex: mixed progesterone-receptor (PR) agonist-antagonist profile (FAS-like atypical PR modulator) + weak androgen-receptor (AR) agonism + weak estrogen-receptor (ER) antagonism + indirect GnRH suppression. As endometriosis Rx: 2.5 mg orally twice weekly for 6 months, endometrial atrophy + amenorrhea + symptomatic improvement in 70-80% (Fedele 1989 PMID 2660361). Significantly receded in the EU market since the 2010s (due to newer endometriosis agents – GnRH agonists + Dienogest), but still Rx in some countries (Brazil, Italy). In bodybuilding context Gestrinone was briefly marketed in the 1990s-2000s as an anti-aromatase-like adjunct, or occasionally as an 'oral SARM substitute' on the UGL market – BUT real anabolic activity tests (rat ventral prostate + levator ani) showed weak potency; clinical bodybuilding benefits are more anecdotal than documented. WADA-banned year-round (S1.1.a – anabolic agent category). Classified in 19-Nor framework due to structural 19-carbon methyl removal + progestogenic activity. Cross-related: not a cross-framed entry, a single-entry compound with 19-Nor classification.
Mechanism
Mixed PR agonist-antagonist + weak AR + weak ER antagonist + GnRH suppression
Anabolic:Androgenic
Weak (low in classical rat bioassay, ~10-20% of Test)
Half-life
~24 h (oral)
Onset
2-4 weeks (endometriosis Rx symptomatic improvement 4-6 weeks)
Legal status
Endometriosis Rx in Europe (Dimetrose) historically; withdrawn in several countries today. WADA-banned S1.1.a.
Data console
Lab data
Safety
Side effects, stop signs, contraindications
Side effects · 8
- Androgenic side effects: acne, oily skin and hirsutism (excess hair growth), the most common adverse effects reported in clinical endometriosis trials.
- Virilization in women: irreversible voice deepening and clitoral enlargement can occur, especially with prolonged or higher-dose use.
- Adverse lipid profile: reduction in HDL (good cholesterol), a hallmark of 17alpha-ethynyl steroids that raises cardiovascular risk.
- Liver enzyme elevation: ALT/AST can rise moderately (roughly 1.5-3x) even at therapeutic doses, due to the slowed hepatic metabolism from the 17alpha-ethynyl substitution.
- Amenorrhoea and menstrual disturbances: hypothalamic suppression and endometrial atrophy thin or stop menstruation; breakthrough spotting can also occur.
- Gastrointestinal symptoms: nausea and abdominal discomfort occur in about 20% of patients in clinical trials.
- Fluid retention, weight gain and peripheral edema as a consequence of the androgenic-progestogenic activity.
- Mood and CNS effects: mood changes, depression, headache and occasional hot flashes due to the hormonal suppression.
Contraindications · 7
- Pregnancy and breastfeeding: absolute contraindication because the drug is teratogenic and can virilize fetal sexual development; reliable non-hormonal contraception is required in women of childbearing potential.
- Severe hepatic dysfunction or active liver disease: contraindicated due to the hepatic burden from the 17alpha-ethynyl substitution.
- High cardiovascular risk: contraindicated in cardiovascular disease, uncontrolled hypertension or a history of thromboembolism because of HDL reduction and fluid retention.
- Severe renal dysfunction: fluid retention can worsen pre-existing kidney disease.
- Competitive and elite sport: banned year-round by WADA (S1.1.a anabolic agent category), with metabolites detectable in urine for 7-14 days, so it must be absolutely avoided by athletes.
- Hormone-sensitive tumors or undiagnosed abnormal genital bleeding: require evaluation before use given the hormonal activity.
- Concurrent hormonal contraception: gestrinone can reduce its effectiveness, so concurrent use is not recommended.
Related Performance Compounds
Same therapeutic category
Studies
Related research and clinical findings
Progesterone receptor modulators for endometriosis.
Fu J, Song H, Zhou M, Zhu H, Wang Y, Chen H, Huang W
Gonadotropin-releasing hormone analogues for endometriosis.
Veth VB, van de Kar MM, Duffy JM, van Wely M, Mijatovic V, Maas JW
Effectiveness and Safety of Postoperative Medical Treatments Following Fertility-Preserving Surgery for Endometriosis: A Systematic Review and Meta-Analysis of Randomised Controlled Trials.
Xiong Y, Huang W, Wang C
Adverse health consequences of performance-enhancing drugs: an Endocrine Society scientific statement
Pope HG Jr, Wood RI, Rogol A, Nyberg F, Bowers L, Bhasin S.
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The information here is for educational and scientific purposes only. Performance-enhancing compounds (AAS, prohormones, stimulants, doping agents) are illegal without prescription in Hungary and most of the EU, and carry serious health and legal risks. WADA bans them in competitive sport. This is NOT a usage guide, and we do not encourage any illegal use. If you do use them, medical supervision and regular bloodwork are ESSENTIAL. Severe endocrine, cardiovascular, hepatic and psychiatric side effects are possible.