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Pmb3.8
Methenolone (Primobolan) Research
Mostly mechanism / observationalLimited safety
5 peer-reviewed studies
What the evidence says
Mostly mechanism / observational
Most Methenolone (Primobolan) studies are mechanism or observational rather than RCTs that measure a clinical effect — keep findings provisional.
Most evidence is from mixed-quality studies published 1975–2024 with a typical study size of 39 participants.
Based on 5 studies · 111 total participants
Confidence
Low
By outcome
Anemia & hematology
Too few graded studies2 studies
Lean mass & anabolic effect
Too few graded studies2 studies
Androgenic & hormonal effects
Too few graded studies2 studies
Safety profile
Too few graded studies2 studies
Cholesterol & lipids
Too few graded studies1 study
Steady research
1 study in the last 5 years
197519992024
1In Vitro1984
1 alpha-Methyl-5 alpha-dihydrotestosterone (1 alpha-methyl-DHT; mesterolone) bound most avidly to sex hormone-binding globulin (SHBG) [relative binding affinity about 4 times that of DHT].
Saartok T, Dahlberg E, Gustafsson JA. · Endocrinology (1984)
Receptor-binding study comparing anabolic-androgenic steroids' affinity for the androgen receptor in muscle and prostate and for SHBG
Mesterolone (1α-methyl-DHT) bound SHBG about four times more avidly than DHT — the mechanistic basis for its SHBG-displacement / free-testosterone effect
Its androgen-receptor binding in muscle and prostate was relatively weak (below testosterone), consistent with it being a weak anabolic
Favorable responses were achieved in 17 patients (44%, 8 good and 9 minimum responses)... anabolic steroids are well tolerated and effective for the treatment of anemia in a subset of MMM patients.
Shimoda K, Shide K, Kamezaki K, Okamura T, Harada N, Kinukawa N, Ohyashiki K, Niho Y, Mizoguchi H, Omine M, Ozawa K, et al. · International journal of hematology (2007)
The best available clinical evidence for the historical anemia use — a retrospective analysis of 39 patients with myelofibrosis with myeloid metaplasia treated with anabolic steroids (including methenolone) in Japan
Favourable hemoglobin responses (≥1.5 g/dL rise and/or transfusion independence) in 44% of patients; adverse events were described as moderate and transient
Observational, not randomized — it grounds the erythropoiesis/anemia mechanism in real patients but is retrospective, and only some patients received methenolone specifically
Objective remissions lasting longer than 3 months occurred in 8 out of 41 evaluable patients... The therapeutic efficiency of Primobolan Depot is comparable to that of testosterone propionate but the agent is less virilising.
Notter G · Acta radiologica: therapy, physics, biology (1975)
The historical oncology indication: a case series of 43 women with disseminated/inoperable breast carcinoma treated with methenolone enanthate (Primobolan Depot) 400–1200 mg/week for at least 3 months
Objective remissions >3 months in 8 of 41 evaluable patients; soft-tissue metastases responded best, while liver and brain metastases were unaffected
Efficacy reported as comparable to testosterone propionate but less virilizing — an early observation of methenolone's comparative mildness as an androgen
In ten women hyperlipoproteinaemia type IIa was demonstrated in the course of treatment, while in two there was hyperlipoproteinaemia type IIb. One of the latter patients had a myocardial infarction in the course of treatment.
Garbrecht M, Lehmann U, O'Brien S, Stolzenbach G, Müllerleile U · Deutsche medizinische Wochenschrift (1981)
The mandatory counter-evidence on harm: an observational study of 28 menopausal women given additive methenolone enanthate during breast-cancer treatment, examining its effect on lipid metabolism
Hyperlipoproteinaemia developed in 12 of 28 women on treatment, and one patient with type-IIb hyperlipoproteinaemia had a myocardial infarction during therapy
The hyperlipoproteinaemia regressed once methenolone was discontinued, and showed no dose relationship — a reversible but real adverse lipid signal
He was treated with methenolone acetate and darbepoetin for anemia caused by myelodysplastic syndrome. During anemia treatment, the decline in bone mineral density was attenuated over time.
Ushimaru S, Sumi H, Aso M, Fujishima R, Shiizaki K, Tominaga N · JCEM case reports (2024)
A contemporary (2024) single case report — an older man with stage-4 chronic kidney disease and myelodysplastic syndrome treated with methenolone acetate plus darbepoetin for the anemia of MDS
Documents methenolone acetate (the oral form) still in use for marrow-failure anemia, and an incidental attenuation of bone-mineral-density decline during treatment
Lowest tier of evidence (n=1, no control), included to show the anemia indication persists in modern practice and the kind of case-level data that is the bulk of methenolone's recent literature