Ethylestrenol is an unusual derivative of nortestosterone that is commonly known by one of its trade names, Orabolin. It lacks the double bonded oxygen at position 3 and is 17-alpha ethylated as opposed to methylated (or alkylated). All classic steroid hormones have some kind of functional group at the 3-position, in most cases a double bonded oxygen (known as a ketone) or a single bonded oxygen bound to hydrogen (known as an alcohol). While several researchers have shown a 3-functional group to be dispensable for androgen receptor binding, the lack of such a group does decrease binding significantly.
Ethylestrenol has very poor binding affinity for the androgen receptor. In fact, it is virtually inactive at all receptors. There is some evidence that this steroid acts as an aromatase inhibitor, which may increase natural testosterone levels. It has been shown that ethylestrenol undergoes conversion to norethandrolone as well as 3-hydroxy metabolites1.
There is little to no conversion to estrogenic metabolites and while ethylestrenol is subject to 5-alpha reduction, like nandrolone, less potent metabolites are formed. This results in a high anabolic to androgenic ratio2. Ethylestrenol has no binding to SHBG3. Unlike norethandrolone, ethylestrenol has been shown to decrease total and free cortisol levels without effecting CBG levels4. When this steroid was originally marketed, it was used primarily by women because it was considered to be weak and didn’t seem to produce androgenic side effects
Ethylestrenol is manufactured by some legitimate pharmaceutical manufacturers around the world but it is not often found on the black market. Most consider it to be too weak. However, at higher doses (100-150 mg per day), this steroid provides for a fairly potent anabolic effect with very little androgenic or estrogenic side effects. The only real concern at this dose would be liver toxicity but the 17-ethyl group seems to be less toxic than the traditional 17-methyl.
1. Schanzer W: Metabolism of anabolic androgenic steroids. Clin Chem. Jul;42(7):1001-20, 1996
2. Pavlatos AM, Fultz O, Monberg MJ, Vootkur A, Pharmd: Review of oxymetholone: a 17alpha-alkylated anabolic-androgenic steroid. Clin Ther. Jun;23(6):789-801; discussion 771, 2001
3. 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
4. Barbosa J, Seal US, Doe RP: Effects of anabolic steroids on hormone-binding proteins, serum cortisol and serum nonprotein-bound cortisol. J Clin Endocrinol Metab. Feb;32(2):232-40, 1971
Adapted with permission from Seth Robert’s Anabolic Pharmacology, all rights reserved.