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Anabolic steroid preparations: basic concepts

 
, medical expert
Last reviewed: 12.04.2020
 
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In order to understand how anabolic steroid drugs work on our body, several concepts need to be introduced. Do not be scared - no special knowledge will be required from you.

A substance is called endogenous if it is produced by the body (endogenous testosterone - testosterone produced by the body), and exogenous if ingested from the outside. All the existing ways of getting drugs into the body can be divided into two large groups of enteral (through the digestive tract) and parenteral (bypassing the digestive tract). The first include: oral administration (oral), resorption under the tongue (sublingually), introduction to the duodenum and rectum (rectally); to the second - the introduction of drugs with the help of injections, usually in the muscle, under the skin or in a vein. As for the anabolic steroid drugs that we are interested in, they are administered either orally or by intramuscular injection; it rarely makes sense to administer them sublingually. Such drugs as insulin or growth hormone are injected with subcutaneous injections.

Drugs administered through the digestive tract must cross the liver barrier before entering the general bloodstream. The liver is always on guard, protecting our body from ingesting foreign substances, many of which can be poisonous. The liver will destroy, as far as possible, any substance that it considers to be foreign. Thus, usually a smaller amount of active substance enters the total bloodstream than was injected into the body. The ratio between the first and second numbers is called the bioavailability of the drug. Simply put, bioavailability indicates what percentage of the administered amount of the drug will actually work.

Most drugs in the body undergo biotransformation, i.e. Different transformations. There are two main types of drug conversion: metabolic transformation and conjugation. The first means the transformation of substances due to oxidation, the second is a biosynthetic process, accompanied by the addition of a number of chemical groups or molecules of endogenous compounds to the drug or its metabolites. Anabolic steroids are exposed in the body to both metabolic transformation and the subsequent conjugation.

Almost all the transformations taking place in the human body need some kind of "outside" assistance. If you have not completely forgotten the school chemistry course, then it is easy to remember that substances that accelerate the course of chemical reactions are called catalysts. Catalysts of the same chemical reactions occurring in any living organism are called enzymes. But besides catalysts, there are also other substances that slow down chemical reactions. His name is inhibitors.

The effect of drugs is largely determined by their dose: the higher it is, the faster the effect of the drug develops, depending on the dose, the severity, duration, and sometimes the nature of the effect changes. The dose is called the amount of the drug at one time - this is a single dose. Doses are divided into threshold, average therapeutic, higher therapeutic, toxic and deadly.

  • Threshold is the dose in which the drug causes an initial biological effect.
  • The average therapeutic dose is the dose in which the drugs cause the necessary pharmacotherapeutic effect in most patients.
  • The higher therapeutic doses are applied when the required effect is not achieved with the help of average therapeutic doses; it is worth noting that, in the case of higher therapeutic doses, the side effects of the drug are still not expressed.
  • In toxic doses, drugs begin to cause toxic effects to the body.
  • Well, you do not need to explain what are the lethal doses to you.

The difference between the threshold and toxic doses of the drug is called the breadth of the therapeutic effect.

With the repeated use of drugs, there is often a decrease in their effectiveness. This phenomenon is called tolerance (addiction), and can be associated with a decrease in absorption of the substance, an increase in the rate of its inactivation or an increase in the intensity of excretion. Adapting to a number of substances may be due to a decrease in the sensitivity to them of receptor formations or a decrease in their density in tissues.

In order to judge the rate of excretion of substances from the body, use such a parameter as the half-life (or half-elimination to whom it is more convenient). The half-life is the time after which the concentration of the active substance in the blood plasma is reduced exactly by half. It should also be borne in mind that the half-life is determined not only by the removal of matter from the body, but also by its biotransformation and deposition. Now about the receptors, they serve as one of the "targets" for medicines. Receptors are the active groupings of the molecules of substrates with which the substance interacts. Receptors, like other molecules, have a certain half-life: reducing this period leads to a decrease in the number of corresponding receptors in the body, and lengthening, naturally, to an increase in this number. We will digress from all other receptors, we will be interested in hormonal receptors in the future, and we will pay special attention to androgen receptors. All hormonal receptors can be divided into two broad categories: receptors within cells (including steroid and thyroid hormone receptors) and receptors on the cell surface (all the rest, including growth hormone receptors, insulin-like growth factor, insulin, and adrenoreceptors). It should be said that the number of receptors on the cell surface can decrease (this phenomenon is called downregulation), and the sensitivity to the corresponding drug can thus be reduced. Receptors inside the cells of downregulation are not subject (in any case, there is no documentary evidence to that).

Androgen receptors (AP), of course, also fall under the general definition of receptors. To put it more simply, the androgen receptors are such very large protein molecules, consisting of about 1000 amino acids and located inside the cells. Different, I must say, cells, not only muscle fibers. Previously, it was believed that there are several types of androgen receptors; Now everyone knows that he is alone.

It should be noted that molecules of different substances can bind to the same receptor. The action that they cause in this case also differs significantly. Substances, molecules of which bind to receptors, are divided into two large groups - agonists and antagonists. Agonists are those substances whose molecules, binding to receptors, cause a biological effect. If we talk about hormonal receptors, then their agonists copy the action of endogenous hormones, more or less successfully. Endogenous hormones themselves, naturally, are also agonists. Antagonists also bind to receptors, but they do not do anything. Antagonists - such a "dog in the manger": unable to activate, the receptor, they at the same time do not allow to join the receptors agonists and do something "useful." The use of antagonists at first glance seems pointless, but only at first glance. To this group of substances are, for example, some antiestrogenic drugs; blocking estrogen receptors, they reduce the risk of side effects associated with the aromatization of AAS by almost sweat.

Here, perhaps, and all the basic concepts that we need to understand how the anabolic steroid drugs work.

trusted-source[1], [2], [3], [4], [5], [6], [7], [8], [9]

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