353 In the index

Drostanolone Mast

A steroid (sold as Masteron) once approved for breast cancer treatment before newer drugs replaced it, now used off-label by bodybuilders for a leaner, more defined look. Its cancer-treatment use is backed by older clinical trials; its bodybuilding use is based on user experience rather than actual studies.

Also known as Masteron, dromostanolone, Metholone, Medrotestron, Medrosteron, Drostanolona, Drostanolonum, 2alpha-Methyldihydrotestosterone

Effects Build muscle Lose fat

Routes Injectable

Legal status Controlled substance

WADA Banned at all times

3D Molecular Structure of C₂₀H₃₂O₂

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Chemistry

Formula: C20H32O2
Molar mass: 304.5
CAS: 58-19-5
PubChem CID: 6011
IUPAC name: (2R,5S,8R,9S,10S,13S,14S,17S)-17-hydroxy-2,10,13-trimethyl-1,2,4,5,6,7,8,9,11,12,14,15,16,17-tetradecahydrocyclopenta[a]phenanthren-3-one
InChIKey: IKXILDNPCZPPRV-RFMGOVQKSA-N

Reported dosing

User-reported

What has been reported in the literature and by users. This is a record of what is done, not a recommendation.

Typical dose 300-400 mg/week

Reported range 200-600 mg/week

Route Intramuscular injection

Frequency Every other day to twice weekly

Duration 6-10 week cycles (unregulated use)

Also known as Masteron; a Schedule III controlled substance with no current approved human medical use in the US. No legitimate clinical dosing exists.

Where this comes from User-reported/bodybuilding literature; historical oncology data (discontinued)

There is no approved human dosing for this compound. The figures above are what users and vendors report, not what has been established as safe or effective. Treat them as a record of what is done, not as guidance.

Variants

Name	Abbr	Route	Notes
Drostanolone propionate	Mast P	Injectable	Short ester Masteron, most common form.
Drostanolone enanthate	Mast E	Injectable	Long ester Masteron for less frequent injections.