Prohormones

Alpha Labs prohormones supplied for laboratory research in the UK: Epistane, Trenavar (Trendione) and M-Sten (Methylstenbolone). Each is encapsulated in the UK, batch numbered, and every batch is independently tested with its certificate of analysis published on the product page and the Lab Testing page.

What prohormones are

Prohormones are steroid precursors or structurally modified steroids that are converted by the body's own enzymes, or act directly, on the androgen receptor. They are not SARMs: SARMs are non-steroidal molecules designed to bind the androgen receptor selectively, whereas prohormones are steroidal and follow the classical steroid pathway. That distinction matters for the research questions each class is used to study, and for how the two are treated in law and in sport.

The three compounds in this range

Epistane (2a,3a-epithio-17a-methyl-5a-androstan-17b-ol) is a methylated derivative of epitiostanol, a compound that was investigated in Japan in the 1960s and 1970s as an anti-oestrogen. It is studied for its androgen receptor activity and its lack of aromatisation.

Trenavar (estra-4,9,11-triene-3,17-dione) is a 17-keto analogue that converts to trenbolone in vitro and in animal models. It is the most potent compound in the range on a per-milligram basis in receptor binding assays and is listed under WADA S1.

M-Sten (2,17a-dimethyl-5a-androsta-1-en-17b-ol-3-one) is a 17-alpha-methylated compound structurally related to methasterone. Methylation at the 17-alpha position is what allows oral bioavailability and is also the feature associated with hepatic strain in the published prohormone literature.

What the research shows

The peer-reviewed literature on prohormones is thinner than for SARMs, and most of it concerns earlier, weaker compounds such as androstenedione and DHEA. Those human studies reported measurable shifts in liver enzymes, HDL cholesterol and endogenous testosterone during the study period. Case reports on methylated prohormones describe cholestatic liver injury in some subjects. Read the compound specification and the published references linked on each product page before buying, and see SARMs 101 for how the two classes differ.

Legal status in the UK, 2026

Prohormones are not controlled under the Misuse of Drugs Act in the UK, but they are not licensed medicines and cannot be sold or marketed for human consumption. Several, including Trenavar and Epistane, are prohibited at all times in sport under WADA S1 (anabolic agents). Buyers outside the UK should check their own country's rules: our guides cover the USA, Australia and Canada.

Research guides

Each compound has its own guide covering the published literature, the case-report record and the legal position: Epistane research guide, Trenavar (Trendione) research guide and M-Sten (Methylstenbolone) research guide.

Related ranges

Support supplements for research contexts are in PCT and Cycle Support. Non-steroidal research compounds are in SARMs, and the full SARMs stacks range is listed separately.

Frequently asked questions

Are prohormones legal to buy in the UK?

Yes. They are not controlled substances in the UK. They are sold strictly for laboratory research, are not licensed medicines and are not for human consumption.

What is the difference between prohormones and SARMs?

Prohormones are steroidal and act through the classical steroid pathway; SARMs are non-steroidal and were designed to bind the androgen receptor selectively. The research literature, the legal treatment and the WADA classification differ between the two.

Is every batch tested?

Yes. Every batch is independently tested and its certificate of analysis is published on the product page and on the Lab Testing page.

Which prohormone is strongest?

In receptor binding assays Trenavar is the most potent per milligram, followed by M-Sten, then Epistane. Potency in an assay is a research characteristic, not a recommendation.

Products are supplied strictly for laboratory research and are not for human consumption. 18+ only.