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What is 11-oxo?

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Target hormone:  17-Hydroxyandrost-4-ene-3,11-dione

Known as:  11-oxo, 11-keto, 11-Keto, Adrenosterone

Half life: 5 hours

Molar Mass: 302.

adrenosterone chemical structure

Fig 1. Adrenosterone (11-Oxo) chemical structure

What is 11-oxo?

11-OXO known as adrenosterone,  is a prohormone produced in the adrenal glands.

11-OXO is a prohormone and it's conversion hormone is known as 11-ketotestosterone   , which is quite an interesting hormone, being a mild androgen in humans and a sex steroid in fish. 11-oxo is a non-aromatizing analogue of Testosterone, which causes dry lean gains and fat loss, along with an increased sexual desire.

11-oxo's conversion to 11-ketotestosterone in humans is much of what contributes to it's noticeable androgenic effect in the user.

11-Keto-androstenedione or 11-keto-androstenetrione are trademark names for this hormone, while the correct name would be androst-4-ene-3,11,17-trione., however this article we will mostly refer to it as 11-oxo.

Why is 11-oxo used in a Cycle Stack?

Although a mild muscle builder itself, 11-oxo also has an aspect welcomed by Bodybuilders looking to retain muscle mass and rid themselves of fat.  This prohormone is capable of   inhibiting the function of the enzyme called: 11beta-hydroxysteroid dehydrogenase type1 reductase (11HSD1R)... This enzyme is   responsible for converting the harmless cortisone to the actively catabolic (muscle wasting) cortisol.  Not only does Cortisol waste muscle mass but it is a key component in promoting fat deposit in men around the oblique and chest area.  11-oxo inhibits this enzymatic activity that creates Cortisol in fat and muscle tissue,  by occupying the enzyme and not allowing it to do it's job.  Simply put, cortisone  cannot be converted into Cortisol, thus causing tissue  cortisol levels to plummet.

The Bodybuilding implications of lowered Cortisol by the competitive ezymatic inhibition that 11-oxo offers, is that even though cortisol is lowered in the tissues, meaning less fat storage, it still allows for cortisol to be present and carry out its important actions in the body.

Any Bodybuilder running a serious cycle would welcome the addition of a compound that has the capability to selectively target the actions of Cortisol that make us fat, while allowing it to do it's other jobs in the body.  This causes minimal side effects from too low levels of cortisol.

How do I use 11-oxo in a Cycle?

11-OXO will provide benefits of increased fat loss and muscle hardening ran on its own in doses ranging from 300mg to 500 mg orally and 180 mg applied topically everyday.   11-oxo can pass through the skin with the right carrier, thus is can be applied right on the mid section and chest.  This results in a much lower dosage being needed since more of the hormone gets into the system when applied on the skin, as opposed to ingesting this non-methylated hormone and making it suffer the chemical inferno of gastric digestion.  Since it does not have a Methyl group to protect it during digestion, Bodybuilders have found that much less Androst-4-ene-3,11,17trione(11-oxo) is lost in delivery when applied topically on the skin.  This results in even less being needed (less than 180mg per day) when transdermal delivery is used, as opposed to the 300mg to 500mg needed to see noticeable effects when used oral.

Although quite mild on it's own and better utilized in a stack with other compounds, the Androst-4-ene-3,11,17trione prohormone known as 11-oxo, does have quite powerful anabolic properties that are noticeable to the user.  Since this prohormone has a conversion to a steroid with a stronger action when it goes from Androst-4-ene-3,11,17trione to it's stronger target conversion steroid known as: 7-Hydroxyandrost-4-ene-3,11-dione –  steroid conversion of this non-methylated prohormone really help 11-oxo's known effects of increasing protein synthesis and noticeable recovery improvement.  It also has shown to have measurable increases in strength.  Most Athletes are reporting seeing the very best results over a 5 to 6 week cycle period using a strong anabolic dosages of 500mg oral, and some are dosing even more.   Gains of a few appreciable pounds of lean body mass can be expected, and at the same time a noticeable amount of fat loss, mostly from it's inhibition of Cortisol.

Obviously Androst-4-ene-3,11,17trione does not contain a Mehtyl group anywhere in it's nomeclature, so it should not impact the liver much even at dosages of  500mg per day oral, for 6 weeks.  This hormone can be used with Formestane and Hexadrone in a great beginner’s cycle to test the anabolic waters.  Although great for a new user, even on it's own, to the experienced Bodybuilder with more than 2 cycles completed, the use of  11-oxo is going to seem mild on it's own.  To the experienced Athlete who is no stranger to chemicals and steroids, the biggest benefits from the anabolic potential of 11-oxo (Androst-4-ene-3,11,17trione) and it's conversion to the much stronger 17-Hydroxyandrost-4-ene-3,11-dione, is best harnessed when it is used in a stack in synergy with other Methylated orals. Being that it is a non-methylated prohormone,  it can be stacked in the same cycle with other compounds. The main role adding 11-oxo would play in a cycle will be in the are of helping minimize fat gain during a bulking cycle, by blocking the enzyme that creates the stress hormone Cortisol, a major culprit in the fat men carry around their mid-section and chest.  Not only the near-targeted fat loss but it can help speed up the rate of strength increases, which in turn will crank up the intensity of the workout's helping the overall synergy of a cycle.

In the cycle formulation LetroZone by GK ProHormones, this very powerful prohomone is used in a topically applied stack, alongside Formestane and other ingredients to lower both Estrogen and Cortisol levels when applied on the skin right over your obliques and chest.  It is a very powerful formulation that takes advantage of 11-oxo's synergistic effects when applied with Formestane.

Does it require a PCT?

Androst-4-ene-3,11,17trione (11-oxo) is a very mild anabolic itself, but it will could still cause suppression at doses over 300mg orally and 120mg topically, but under those ranges it doesn't seem to show any negative impact in the recovery of HTPA, even when used during PCT to a Bridge.  11-oxo creates more possibilities for running “Bridge Cycle” that are non-suppressive nor liver toxic by stacking this prohormone in the same “Bridge Cycle” with another anabolic agent like SARMS or Peptides, both of which are also known to only be mildly suppressive.   Even on the mildest of Bridge cycles, a full and proper PCT should always be used to ensure proper recovery.  Many guys are using HCGenerate and N2Guard during PCT as staples for recovery.

For how long can I use 11-oxo?

When it comes to the prohormone Androst-4-ene-3,11,17trione with it's non-methylated structure, most Bodybuilders are doing 6 -12 weeks, which seems to be the sweet spot.  Any longer than that is not recommended as 11-oxo will increase blood pressure, and the potential for cortisol rebound once the cycle ends drastically increases the longer you use this prohormone.

As with anything, your body will eventually stop responding to anything you take too long, so anything longer than 12 weeks start to become counter productive.  Taking a break, as long as the cycle itself should be plenty to clear out the body and make it  fully responsive to the compound again.

Just because something is non-methylated does not make it safe.  Full PCT and liver support should be used along with every cycle where you use any  steroid, prohormone, prosteroid, SARM, Peptide and/or analogue.    If you are already deciding to risk experimenting with powerful compounds to build muscle, you may as well also used the most powerful compound we know to keep your liver safe during cycle and your libido and fertility strong and healthy.

What are the known side-effects?

Mostly joint dryness and more propensity to injury.  It does NOT convert to Estrogen so that is never a concern with 11-oxo.  It can also cause loss of libido, especially in those prone to erectile dysfunction.  Many users are taking HCGenerate during cycle to keep Libido going strong even while using these powerful prohormones and even steroids.


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Russian Star is an industry leader in peptide design and development. He is a fitness mentor with a Masters degree in molecular chemistry, he's working on his PhD in biochemistry.

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