Understanding Anabolic:Androgenic Ratios

Anabolic and Androgenic

The anabolic:androgenic ratios for steroids and prohormones are often quoted, but what do they mean?

In the 1960s when the majority of steroid research was undertaken, before steroids became a dirty word, the goal of the researchers was to develop steroids that could increase muscle mass (in cancer patients, burn victims, those with wasting diseases etc.) without also causing the secondary male sex characteristics that natural steroids like testosterone can cause (like increased facial hair, deeper voice, enlarged clitoris in females). They were trying to develop steroids that were anabolic without being androgenic.

Of course medical science has pesky moral objections to testing unknown substances on human test subjects (even though these days gymrats are willing to queue round the block to take the latest untested designer steroid compounds), so a system of testing was developed on rats.

The Hershberger Assay

The steroids were administered to rats either orally (through a gavage tube) or by injection. The rats were sacrificed after the experiment (which is known as the Hershberger Assay), and the increase in the weights of the levator ani, seminal vesicles, and ventral prostate, were recorded and compared to a standard such as testosterone (if by injection) or methyl testosterone (if administered orally).
The levator ani is the “tail-wagging” muscle in animals, and as such any increase in weight provides a reasonable estimate of the anabolic nature of the compound.
The seminal vesicles and the ventral prostate are both involved in the production of semen, and are androgen-sensitive tissues, that is they grow when androgenic compounds are administered.

By using these markers, the scientists tried to make compounds that had a high anabolic value (as measured by the levator ani, or L.A) and low androgenic value (as measured by seminal vesicles, S.V., and ventral prostate, V.P.).

Viva la Vida

In the late 1960s a young scientist called Julius Vida spent a long time collecting and reviewing all the available data on steroids that had been published so far. In 1969 he published a book called “Androgens and Anabolic Agents – Chemistry and Pharmacology”. The first part of this book was a discussion on the metabolism, and structure and activity relationships of these compounds, while the second part listed 666 steroids, organised by structure, and for each he listed the steroidal nomenclature (the chemical name for the drug), a structural diagram of the compound, and the anabolic and androgenic values compared to a standard along with the method of administration used to determine them (i.e. oral or subcutaneous injection). He also provides a reference number that refers to a bibliography to show which study the figures were originally published in.
These figures form the basis of the anabolic:androgenic ratios we see quoted today.

In Detail

Here’s an example of one of the compounds listed in Vida’s book.
We aren’t concerned about the number, nomenclature, or chemical structure at the present time. Looking at the method of administration, for the top row it is empty (meaning that the figures on that row were the result of subcutaneous injection) and on the second row it says oral, meaning that the steroid was orally administered to arrive at the figures on that row.

Since this compound is methylepithiostanol, more commonly known as the prohormone/designer steroid “epi” (or by the trade names epistane and havoc), and is currently only available in caps for oral administration, we should only concern ourselves with the figures on the second row – those arrived at by oral admin.

Those figures are given as ventral prostate/seminal vesicles: 91, levator ani: 1100, and the basis of comparison is given as 17a-MT (methyltestosterone).
This gives it an anabolic:androgenic ratio of 1100:91 (compared to methyl test). Methyl test is assumed to be 100:100 for the purposes of this comparison. What this means is that epi is 11 times more anabolic (1100%) and roughly as androgenic (91% as androgenic) as methyl test (by oral administration to rats).

In Conclusion

While these figures do not translate literally to their effects on humans, they tend to give a reasonable impression of the nature of a given steroid. In medical science, these would be the first tests they would do on a newly synthesized compound to determine it’s initial viability. If it proved effective, and had a strong dissociation of anabolic and androgenic effects, it may have progressed to further testing and eventually human trials.

Many prohormones and designer steroids available on the “dietary supplement” market today never progressed beyond this initial animal testing stage, and some of them are entirely novel compounds with no scientific testing undertaken at all.