6-OXO (4-Androstene-3,6,17-trione) Explained

by Mike Arnold

6-OXO was the 1st effective anti-aromatase to hit the OTC market. Originally formulated and marketed by Patrick Arnold, the chemist-guru who brought pro-hormones to the marketplace, including the original 4AD and 1AD, Patrick was the man who helped launch the modern OTC prohormone movement. Patrick has also been responsible for bringing several undetectable designer steroids to elite athletes, has been featured in bodybuilding magazines as a monthly columnist, owns his own supplement company, and is still widely respected as an authority on anabolic chemistry and ergogenic aids. With that said, we will delve into 6-OXO and explain why it is still relevant today.

So, what are aromatase inhibitors? In Short, they are a category of compounds which reduce estrogen in the body, but in order to have a more thorough understanding of how aromatase inhibitors (which will be referred to as A.I’s from this point forward) work, we will need to define some of the other basic terms associated with the subject of aromatase inhibition. First of all, aromatase is an endogenously produced enzyme responsible for the conversion of testosterone into estrogen. Without aromatase, normal physiological functioning is impaired, as estrogen plays a critical role in the lives of males. However, excess aromatase can result in numerous negative side effects, some of which include increased bodyfat gain, female fat pattern distribution, increased blood pressure, water retention, gynecomastia, reduced libido and sexual functioning, as well as the suppression of both natural testosterone production and spermatogenesis.

While it is possible that elevated levels of estrogen may occur naturally, steroid users are often at a greater risk for experiencing these side effects, due to the use of aromatizable drugs, such as testosterone, Dianabol, etc. When administering a drug such as testosterone in supraphysiological quantities, the body’s natural hormonal environment is disturbed, altering the testosterone to estrogen ratio. In an attempt to correct this imbalance and restore equilibrium, the body’s natural response is too aromatize a portion of the available testosterone into estrogen…and the more testosterone that is present, the more interaction will take place between testosterone and the aromatase enzyme.

This reaction may help to correct the T: E ratio, but it will not do anything to protect the body from the effects of excess estrogen levels. If this weren’t bad enough, users of aromatizable drugs often have to contend with the effects of elevated estrogen post-cycle, resulting in a prolonged recovery of the HPTA. Therefore, management of estrogen both during and post-cycle is critical if the individual wishes to avoid estrogenic side effects and restore testosterone production as quickly as possible.

For those who choose to abide by the law when selecting which A.I. to use while on-cycle and during PCT, the task has become much less arduous, due to recent (and what I believe to be unjustified) government regulation of the supplement market. In an industry which has thrived primarily on hype and deceptive advertising over the years, it is important that the product you select is backed with scientific evidence proving its effectiveness. Otherwise, how will you know it does what is claimed? Fortunately, 6-oxo has amassed an impressive amount of scientific support, as well as demonstrated significant real-world results. In a study conducted at Baylor University, 6-oxo was shown to alter estrogen in favor of testosterone, while simultaneously increasing free testosterone and dihydrotestosterone. See below for a copy of the abstract. The text relaying the study results have been highlighted in blue:

Effects of eight weeks of an alleged aromatase inhibiting nutritional supplement 6-OXO (androst-4-ene-3,6,17-trione) on serum hormone profiles and clinical safety markers in resistance-trained, eugonadal males


The purpose of this study was to determine the effects of 6-OXO, a purported nutritional aromatase inhibitor, in a dose dependent manner on body composition, serum hormone levels, and clinical safety markers in resistance trained males. Sixteen males were supplemented with either 300 mg or 600 mg of 6-OXO in a double-blind manner for eight weeks. Blood and urine samples were obtained at weeks 0, 1, 3, 8, and 11 (after a 3-week washout period). Blood samples were analyzed for total testosterone (TT), free testosterone (FT), dihydrotestosterone (DHT), estradiol, estriol, estrone, SHBG, leutinizing hormone (LH), follicle stimulating hormone (FSH), growth hormone (GH), cortisol, FT/estradiol (T/E). Blood and urine were also analyzed for clinical chemistry markers. Data were analyzed with two-way MANOVA. For all of the serum hormones, there were no significant differences between groups (p > 0.05). Compared to baseline, free testosterone underwent overall increases of 90% for 300 mg 6-OXO and 84% for 600 mg, respectively (p < 0.05). DHT underwent significant overall increases (p < 0.05) of 192% and 265% with 300 mg and 600 mg, respectively. T/E increased 53% and 67% for 300 mg and 600 mg 6-OXO, respectively. For estrone, 300 mg produced an overall increase of 22%, whereas 600 mg caused a 52% increase (p < 0.05). Body composition did not change with supplementation (p > 0.05) and clinical safety markers were not adversely affected with ingestion of either supplement dose (p > 0.05). While neither of the 6-OXO dosages appears to have any negative effects on clinical chemistry markers, supplementation at a daily dosage of 300 mg and 600 mg for eight weeks did not completely inhibit aromatase activity, yet significantly increased FT, DHT, and T/E.

Among the various AI’s, they are divided into two different classes, known as Type 1 and Type 2 anti-aromatases. 6-OXO belongs to the Type 1 class of A.I’s, due to its ability to permanently deactivate estrogen at the aromatase enzyme. This is known as suicide inhibition and is a favorable attribute, as it prevents the possibility of experiencing estrogen rebound after cessation of 6-OXO. Other anti-aromatases, such as Exemestane and Formestane, are also suicide inhibitors, while Letrozole and Anastrozole are not.

In addition to the avoidance of estrogen-related side effects, 6-OXO may impart cosmetic benefits, such as an increase in the hardness & dryness of the musculature. This is primarily due to an overall decrease in the body’s level of estrogen–induced water retention and/or a more favorable ratio of androgens to estrogen, allowing the individual to showcase a more visually pleasing physique. 6-OXO also serves as an SHBG modulator, contributing to a further increase in free testosterone. While SHBG (sex hormone binding globulin) is a necessary hormone, it is also directly responsible for making most of the testosterone we produce/administer unavailable for use by the body. It accomplishes this by irreversibly binding to testosterone in the bloodstream, rendering it completely inactive and worthless for muscle-building…or anything else for that matter. In fact, about 98% of all circulating testosterone is bound by this seemingly adversarial protein. Needless to say, a reduction of SHBG is advantageous for those trying to add lean muscle tissue and 6-OXO helps to achieve this.

Whether you are looking to utilize 6-OXO as a part of your post-cycle therapy, to control estrogen while on-cycle, or to improve the visual appearance of your physique, 6-OXO is an effective adjunct to your program.

6-OXO is available from IronMagLabs: E-Control Rx

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