Steroids - What do you know?

Anabolic/Androgenic Steroids can be roughly classified into two types, oral and injectable. When you eat food or consume anything orally, the great majority of the ingested substances pass through the liver prior to entering the bloodstream. For this reason, "injectable" AAS cannot be taken orally because the liver will deactivate the steroids in this "first pass". Deactivation in the liver usually involves the addition of one or more hydroxyl (OH) groups to increase the solubility of the molecule in water, making excretion in the urine more easily accomplished.

Oral Steroids
Oral steroids involve modification of the parent steroid to make it harder for the liver to degrade the steroid molecules. This modification is almost always the addition of an alkyl (methyl) group at the 17 position of the steroid ring. The liver can still degrade the steroid, but not as effectively as the un-modified steroid. Therefore, oral steroids make several cycles through the bloodstream before being excreted. Most oral steroids are, to various degrees, excreted from the body unchanged
Injectable Steroids
The injectable Steroids are very effectively degraded in just a single pass through the liver. If this is so, then how can the injectables be effective? The answer is called a "depot" (or reservoir), which allows a regular release of steroid into the bloodstream. As steroid is removed from the bloodstream by the liver, more steroid is being released into the bloodstream from the depot. There are several ways to provide such a reservoir of the steroid.

Suspension
The first way is to use pure testosterone (a crystalline solid) suspended in water. Testosterone has a low solubility in water, and the crystals slowly dissolve in the watery environment of the tissue in which it is injected. The dissolved testosterone is carried throughout the body by the bloodstream. For Testosterone suspension, the "depot" is the actual physical site where the injection is made. The crystals do not migrate to other parts of the body, and the presence of the crystalline testosterone can cause some pain at the injection site. The testosterone dissolves at a (relatively) constant rate, and lasts for a few days in the body. Winstrol suspension is similar.

Esters
The other way to provide a depot of steroid is to use a water-insoluble form of the steroid that can be converted in the body to the parent steroid, which has some solubility in water (bloodstream). Most commonly, the parent molecule is esterified with an organic acid, and the resulting ester is soluble in oil, but only very slightly soluble in water. Commonly used organic acid groups are acetate (C2), propionate (C3), enanthate (C7), decanoate (C10), and undecylenate (C11). The longer the carbon chain of the acid, the more oil-soluble the ester, and the longer it takes for the ester to turn into the parent steroid (de-esterification). A type of enzyme that is found throughout the body facilitates the de-esterification reaction to form the parent steroid from the ester. The enzyme actually catalyzes the reaction in both directions, so it can also attach an organic acid back onto the parent steroid. So, for example, testosterone enanthate can actually be turned into testosterone palmitate. There is some good evidence that steroid esters are, to some extent, stored in fat cells.

It is commonly believed that esters form a depot of oil/ester that stays at the injection site. This is not true. While the depot concept holds true for esters (because they slowly release the parent steroid over time), the esters actually disperse throughout the body after injection, prior to (and during) the de-esterification reaction to form the parent steroid. They do not stay at the injection site. For example, the ester testosterone enanthate has been found in tissues throughout the body, including hair samples of subjects who have injected T200. If a bio-contaminant is introduced at the time of injection (non-sterile conditions), the body will attempt to encapsulate the contaminated material, and an abscess will form. In this case it appears as if the ester has remained at the injection site. But under normal sterile conditions, the oily solution will disperse. Injecting too much at one site or injecting too frequently at one site will not cause an abscess.

Transport of Steroids in the Bloodstream
Once the steroid has been released from the depot (or the oral steroid has been absorbed from the intestine), it is transported throughout the body in the bloodstream. Carrier proteins (Albumin and Sex Hormone binding Globulin) bind about 98% of testosterone under natural conditions. Thus, only 2% of the hormone is free to carry out its actions. When exogenous steroid is present, the level of free steroid is much higher than 2%. Bear in mind that the hormone is not permanently bound to the some of the proteins, but is constantly binding and un-binding from the protein. At any given time, about 2% of the hormone is un-bound in the natural state. So, if the 2% unbound hormone were to magically disappear, then the proteins would release more hormone such that 2% (of the remaining total) would come unbound. The bloodstream is the mechanism by which the hormones reach their target tissues (muscle).