Mesterolone Enanthate
A hypothetical/underground injectable enanthate ester of mesterolone (Proviron), a 1-methyl DHT derivative normally taken orally without a 17-alpha-alkyl group. Esterifying mesterolone as an enanthate would allow a depot injection, converting an ordinarily weak, non-hepatotoxic oral androgen into a longer-acting injectable. It is essentially unstudied in this form and rarely encountered.
01 Overview
Mesterolone is used clinically as an oral androgen and, in bodybuilding, mainly as an anti-estrogenic, SHBG-lowering ancillary rather than a mass-builder. It is not 17-alpha-alkylated, so it is not notably hepatotoxic, but its oral bioavailability is modest. An enanthate ester would provide sustained release from an intramuscular depot, an approach that has essentially no pharmaceutical precedent for this molecule.
Because no pharmaceutical or veterinary mesterolone enanthate exists, all information is extrapolated from oral mesterolone plus general ester pharmacology. Expect a mild anabolic effect, strong binding to SHBG that frees up other androgens, and androgenic rather than estrogenic side effects. It should be treated as poorly characterised.
02 Mechanism
Mesterolone is a DHT-derived androgen receptor agonist that also binds SHBG and aromatase; the enanthate ester would slowly release it from an intramuscular depot.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Ancillary | 50–100 mg/wk | IM | Used mainly for SHBG reduction and anti-estrogen feel. |
| Higher | 100–200 mg/wk | IM | Anecdotal; no established injectable protocol. |
Ester comparison
| Ester | Half-life | Injection freq. | Testosterone by mass |
|---|
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Lowered SHBG / more free androgenMesterolone binds SHBG, freeing other androgens for activity. | Increased free testosterone | Observational | |
| Anti-estrogenic feel and hardeningUsers report a drier look and mood/libido lift, partly via reduced estrogen activity. | Mild | Anecdotal |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Androgenic effectsAcne, oily skin and potential acceleration of male-pattern hair loss. | Mild | Common in predisposed users | Observational | |
| Prostate effectsAs a DHT derivative it may aggravate prostate growth in older users. | Mild | Uncommon | Observational | |
| HPTA suppressionSuppresses natural testosterone, more so as a depot than the oral. | Moderate | Common at higher doses | Observational |