Gaspari Nutrition Halodrol-50, CEL H-drol, Purus Labs Halovar, EST Hemadrol, Mr Supps Helladrol, Hard Rock Halo-Plex, Pro Cycle Labs Halostane, Primordial Performance Turinabol
This compound was originally released into the bodybuilding “supplement” market by Gaspari Nutrition as “Halodrol-50”. Their ex-product formulator Bruce Kneller tells the story:
“I spent over a year studying the original E. German docs on Oral Turinabol before I changed the ketone to a hydroxyl and launched it. The German doping machine kept amazing notes we had translated back in 2002-2004. Hundreds of pages. with dose of 5mg -500mg per day. Seeing out [sic] Halodrol was weaker than OT (and a precursor to it) I felt very comfortable in being able to predict how it would work.” 
The Halodrol-50 product listed the ingredient as “polydehydrogenated, polyhydroxylated halomethetioallocholane”, however it did not just contain the implied 4-chloro-17a methyl-androst 1,4-diene-3,17b-diol compound. As early as 2005 it was analysed by anti-doping expert Don Catlin and found to also contain the designer steroid Madol (desoxymethyltestosterone, or phera) which had then recently been detected in athletes as part of the BALCO scandal. 
While Catlin’s initial analysis revealed only the presence of madol and 4-chloro-17a methyl-androst 1,4-diene-3,17b-diol, more thorough testing of the Gaspari Nutrition product has since revealed that it also contained methyldrostanolone (superdrol) as well as oral turinabol and several similar analogues that are believed to be the result of crude synthesis techniques. 
The active compound has since appeared in numerous “dietary supplements” sold on the internet and in gyms and sports supplement shops.
Structure and Function:
Like many oral prohormones/designer steroids/anabolic steroids on the market, this compound has a 17a-methyl group. This functional group increases oral activity by preventing 17b-hydroxyl oxidation from occurring.
It has a covalent bond structure like that of Oral Turinabol. It differs from Oral Turinabol in that it has a hydroxyl function at carbon 3 instead of a ketone.
Though the nomenclature found on h-drol bottles says 4-chloro-17a methyl-androst 1,4-diene-3,17b-diol, the 3-hydroxyl is not planar; it must be either a 3b-hydroxyl or a 3a-hydroxyl. In truth commercial h-drol clones contain a mixture of 3a- and 3b-hydroxylated stereoisomers, due to the production process. Typically halodrol is made from Oral Turinabol using reducing agents such as sodium borohydride. The reaction method determines the ratio of isomers produced – which can be anywhere from 50:50 to 95:5 in favour of the 3b-ol.
This 3-hydroxyl is intended to be metabolised by the body back to a 3-ketone; h-drol is taken as a “prohormone” (precursor) to Oral Turinabol.
The 4-chloro modification also prevents Halodrol from aromatizing. The same substitution is found in the injectable steroid Clostebol and the oral steroid Turinabol: 
“After adminstration of 4-chloro-17b-hydroxyandrost-4-en-3-one-p-chlorophenoxyacetate (100 mg once intramuscularly) and of 4-chloro-17a-methyl-17b-hydroxyandrosta-1,4-dien-3-one (25mg orally daily) to endocrinologically healthy males, there was still no measurable increase in the excretion of estrogens in urine (1163).” 
Oral Turinabol and Halodrol both have a 1,4-diene unconjugated system which will make the steroids very poor substrates for the 5a-reductase enzyme, thus making 5a-reduction highly unlikely.  It should be of note however that, like other 1,4-dienes, this compound will be subject to 5b-reduction.
There is some public skepticism regarding this compound’s ability to convert into Oral Turinabol, as there has yet to be a published study which examines the pharmacokinetic profile of Halodrol in humans. However, a recent in vitro study conducted by a team of researchers reveals the metabolism of Halodrol in equine (horse) liver.  The results of this study are discussed below:
“By far the most abundant metabolite observed by both LC-HRMS and GC-MS was an oxidized metabolite (−2H) proposed to be 3-keto-Halodrol (otherwise known as Turinabol). This is significant since it is therefore likely that Halodrol is a pro-drug for Turinabol (a 3-keto analogue of Halodrol) and that its metabolism could be very similar to this steroid.” 
Other routes of metabolism, from the same study, include oxidation and hydroxylation, A-ring reduction, and combinations thereof.
 Modern Fitness Forum: Turinabol by Primordial Performance
 Washington Post: Steroids Detected In Dietary Tablets
 Gauthier J, Poirier D, Ayotte C. Characterization of desoxymethyltestosterone main urinary metabolite produced from cultures of human fresh hepatocytes. Steroids. 2012 May;77(6):635–43.
 Krüskemper, Hans Ludwig. 1968. Anabolic Steroids. Academic Press.
 Fragkaki AG, Angelis YS, Tsantili-Kakoulidou A, Koupparis M, Georgakopoulos C. Schemes of metabolic patterns of anabolic androgenic steroids for the estimation of metabolites of designer steroids in human urine. J. Steroid Biochem. Mol. Biol. 2009 May;115(1-2):44–61.
 Clarke A. The use of in vitro technologies and high-resolution/accurate-mass LC-MS to screen for metabolites of ‘designer’ steroids in the equine. Drug Test Anal 3:74 (2011)
© Total Flex Blog 2012