Clostebol Acetate
The acetate ester of clostebol (4-chlorotestosterone), a mild anabolic steroid used in some countries in injectable and topical medicinal preparations, including wound-healing ointments. The 4-chloro substitution blocks aromatisation and 5-alpha reduction, giving a mild, non-oestrogenic profile. It is best known in anti-doping circles for causing positive tests via contaminated topical products.
01 Overview
Clostebol is 4-chlorotestosterone; the acetate ester extends its action for injectable use. The 4-chloro group prevents aromatisation to oestrogen and blocks 5-alpha reduction, so clostebol produces neither oestrogenic nor amplified-androgenic effects, making it a comparatively mild steroid. It has a real if limited medical footprint, appearing in some European and South American products, notably topical antibacterial/healing creams (e.g. Trofodermin).
It is frequently discussed in sport because trace exposure from topical clostebol products has produced anti-doping positives at very low levels. As a performance agent it is mild, and its evidence base is a mix of older clinical use and forensic detection studies rather than modern efficacy trials.
02 Mechanism
Androgen-receptor agonist; the 4-chloro group prevents aromatisation and 5-alpha reduction, giving mild, non-oestrogenic androgenic activity.
03 Dosing
| Tier | Dose | Route | Notes |
|---|---|---|---|
| Common | 100–200 mg/wk | IM | Mild anabolic; short-to-medium ester. |
| Heavy | 300–400 mg/wk | IM | Still relatively mild at higher doses. |
Ester comparison
| Ester | Half-life | Injection freq. | Testosterone by mass |
|---|
04 Effects
| Effect | Magnitude | Evidence | |
|---|---|---|---|
| Mild lean muscle gainModest anabolic effect consistent with its mild profile; limited controlled data. | Observational | ||
| No oestrogenic activityThe 4-chloro group prevents aromatisation, avoiding oestrogenic side effects. | Preclinical | ||
| Tissue-healing (topical)Used topically for wound healing in some markets, reflecting mild anabolic action on skin. | Observational |
05 Side effects
| Effect | Severity | Frequency | Evidence | Countermeasures |
|---|---|---|---|---|
| Androgenic effectsMild acne or oily skin; androgenicity is not amplified by 5-alpha reduction. | Mild | Uncommon | Anecdotal | |
| HPTA suppressionSuppresses endogenous testosterone, though more mildly than potent steroids. | Moderate | Common | Observational | |
| Inadvertent anti-doping positiveTrace exposure from topical clostebol products has caused positive doping tests at very low concentrations. | Moderate | Uncommon | Observational |