Drostanolone Undecanoate
A very long-acting undecanoate ester of drostanolone (Masteron), a non-aromatising DHT-derived steroid. While the propionate and enanthate esters of drostanolone are common, the undecanoate would extend release to allow much less frequent injection. It has no pharmaceutical precedent and is a niche underground ester within the drostanolone family, offering Masteron's dry, hardening effect over a longer duration.
01 Overview
Drostanolone is a 2-methyl dihydrotestosterone derivative that does not aromatise and has mild anti-estrogenic activity, giving a hard, dry, defined look used mainly in cutting phases. Existing esters are propionate (very short) and enanthate (medium); an undecanoate ester would greatly lengthen the depot window, in principle to two weeks or more between injections.
There is no clinical or veterinary drostanolone undecanoate and thus no pharmacokinetic data for it specifically. Its profile is that of drostanolone with a slow-release ester: modest anabolism, no estrogenic effects, and androgenic side effects such as hair loss in the predisposed. It should be considered uncharacterised in this ester form.
02 Mechanism
Drostanolone is a non-aromatising androgen receptor agonist with mild anti-estrogenic activity; the undecanoate ester is cleaved slowly to give an extended depot release.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Common | 200–400 mg/wk | IM | Long ester allows once-weekly or less; anecdotal dosing. |
| High | 400–600 mg/wk | IM | Diminishing returns above moderate doses. |
Ester comparison
| Ester | Half-life | Injection freq. | Testosterone by mass |
|---|
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Dry, hard cosmetic effectNon-aromatising profile gives a hard, defined look in lean users. | Improved definition | Observational | |
| Mild anti-estrogenic activityDrostanolone can slightly blunt estrogenic effects of stacked compounds. | Modest | Observational |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Acne and oily skinAndrogenic stimulation of sebaceous glands. | Mild | Common | Observational | |
| Androgenic hair lossAs a potent DHT derivative it can accelerate male-pattern baldness. | Moderate | Common in predisposed users | Observational | |
| HPTA suppressionSuppresses natural testosterone, more persistently as a long ester. | Moderate | Universal at cycle doses | Observational |