Written by justis berg
26 March 2010


Anabolic Pharmacology

By Seth Roberts



Pharmacology is the study of drugs and their effects. Anabolic pharmacology is the study of drugs that have a growth-promoting effect in muscle. This column will explore anabolic pharmacology by profiling a different anabolic drug and its effects each month. The focus of discussion this month will be the anabolic androgenic steroid, Equipoise. 

Boldenone is a 1-dehydro derivative of testosterone that has been sold as a veterinary preparation under the name Equipoise, and is largely known by this name. The formation of a double-bond in the 1,2 position changes the shape of the molecule slightly. This also changes the potency and characteristics of the molecule. Boldenone has a lower affinity than testosterone for the androgen receptor, making it less potent on a milligram-for-milligram basis.1 This steroid can be converted to estrogen, but less so than testosterone. In addition, boldenone is metabolized to 1,4 dienedione, which is a potent aromatase inhibitor.

Boldenone is converted by 5-alpha reductase to 1-testosterone, a more potent steroid, as well as to the 5-beta isomer— which is thought to be an inactive metabolite.2,3 Binding to sex hormone-binding globulin (SHBG) is much lower with boldenone than with testosterone, meaning a larger free plasma concentration but a shorter half-life in plasma.4 There is little-to-no binding to progesterone or glucocorticoid receptors, and no real data on the interaction of boldenone with the different enzyme systems.1

The undecyclenate ester of boldenone was the ester marketed under the original trade name. In recent years, the free base and other esters have become available as underground preparations. On the street, Equipoise is erroneously considered to have the same activity as Deca and is often substituted for Deca in a stack. Dan Duchaine, if not the originator of this myth, at the very least propagated it in his book Underground Steroid Handbook II. If you look at the structure, you can see that boldenone is structurally identical to dianabol without the C-17 alkylation.

Most people experience much less side effects with boldenone, compared to methandrostenolone. This is because boldenone converts to estradiol, while methandrostenolone converts to methylestradiol. Methylestradiol is a much more potent and long-lasting estrogen than plain estradiol. Since there is no C-17 alkylation, there is no liver toxicity associated with boldenone. Boldenone is rumored to be very good at increasing red blood cell production. While all androgens stimulate erythropoiesis, there is no evidence in the scientific literature that boldenone is superior in producing this effect.5,6,7,8

Boldenone undecyclenate is generally injected every four or five days, but some people will inject every day while others will inject once per week. The longer half-life of the undecyclenate ester would dictate an injection frequency of every 10-14 days, but there has been a trend toward more frequent dosing by anabolic-androgenic steroid (AAS) users, even with drugs known to have long half-lives. Dosing is generally kept pretty low (300-500 milligrams per week), but the low binding affinity would argue for twice that dosage, taken with testosterone.

The anabolic-to-androgenic ratios are favorable for boldenone, but people do not consider boldenone a particularly potent steroid— possibly due to the low doses that are utilized. Also, boldenone does not cause much water retention— so many people assume it is not working if they do not put on 10 pounds in one week. Boldenone is said to cause an increase in vascularity, although there is no mechanism to explain why boldenone would do this more than any other AAS.

Seth Roberts is a former pharmaceutical research scientist with over 10 years of pharmacological research in the discovery and development of novel therapeutics. If you want to learn more about Anabolic Steroids, pick up Seth’s new book Anabolic Pharmacology at www.Ergogens.com. [© Seth Roberts, 2009. All rights reserved. For informational purposes only, not to be considered as medical advice or an endorsement of the use of illegal substances.]



1. Ojasoo T, Delettre J, Mornon JP, Turpin-VanDycke C, Raynaud JP: Towards the mapping of the progesterone and androgen receptors. J Steroid Biochem, 27(1-3):255-69, 1987.

2. Schanzer W, Donike M: Metabolism of boldenone in man: gas chromatographic/mass spectrometric identification of urinary excreted metabolites and determination of excretion rates. Biol Mass Spectrom, Jan;21(1):3-16, 1992.

3. Schanzer W: Metabolism of anabolic androgenic steroids. Clin Chem, Jul;42(7):1001-20, 1996.

4. Saartok T, Dahlberg E, Gustafsson JA: Relative binding affinity of anabolic-androgenic steroids: comparison of the binding to the androgen receptors in skeletal muscle and in prostate, as well as to sex hormone-binding globulin. Endocrinology, Jun;114(6):2100-6, 1984.

5. Gorshein D, Murphy S, Gardner FH. Comparative study on the erythropoietic effects of androgens and their mode of action. J Appl Physiol, 35(3):276-8, 1973.

6. Paulo LG, Fink GD, Roh BL, Fisher JW. Effects of several androgens and steroid metabolites on erythropoietin production in the isolated perfused dog kidney. Blood, 43(1):39-47, 1974.

7. Sanchez-Medal L, Gomez-Leal A, Duarte L, Guadalupe Rico M. Anabolic androgenic steroids in the treatment of acquired aplastic anemia. Blood, 34(3):283-300, 1969.

8. Alexanian R. Erythropoietin and erythropoiesis in anemic man following androgens. Blood, 33(4):564-72, 1969.