The liver continuously destroys the steroid hormones present in the blood, down to the simplest metabolites that are excreted in the urine. Therefore, if you do not introduce new portions, then their concentration will decrease. Different drugs are metabolized (destroyed) at different rates. And for its measurement using the concept of half-life.

The structure of testosterone

The half-life (or half-life) is the time during which the concentration of the drug in the blood is reduced by 2 times. That is, with the introduction of 100mg of the drug (with a half-life of 24 hours), after 24 hours only 50 mg will be in the blood. After 48-25 mg. After 3 days – 12.5 mg.

Thus, to maintain a uniform concentration, it is necessary to administer the drug 1 time for each half-life or more often.

Pure testosterone has a half-life of only about 10 minutes. This makes pure testosterone inconvenient to use. Since it would have to prick very often. And in the first minutes after administration, the concentration would be excessively high.

To change certain properties of the hormone (for example, testosterone) in its molecule make some changes: adding and / or disconnecting from it various molecules. At the same time without changing the steroid skeleton itself. The first goal of these changes is to increase the lifetime of the drug in the body or enhance the anabolic properties.

Half-life of injectable steroids

Esterification is used to solve this problem and create longer-lasting drugs. That is, the conversion of a steroid to an ester (salt) of an organic acid. The ester is soluble in oil and injected intramuscularly. When entering the blood, the ether passes through the liver, which detaches the base of the organic acid, and the drug enters the blood.

This process is rather slow, and the dose administered is distributed over a considerable period of time.

Thus, the esterification allows you to greatly increase the half-life and makes the drug more convenient to use. However, the effect of the drug itself does not change. That is, testosterone propionate and testosterone decanoate have exactly the same properties and effect. And differ only in half-life.

All products made in this way are intended for injectable use only.

Half-life of oral steroids

To create drugs suitable for use in the form of tablets, using a different method. The difficulty is that steroids in their pure form are not able to pass through the gastrointestinal tract, the enzymes destroy them instantly. In order that they do not break down there, a CH4 molecule is attached to the steroid molecule at position 17-a. This process is called alkylation, and the steroids obtained in this way are 17-a alkylated. Alkylation at 17-a enhances the anabolic properties of drugs.

All tableted preparations, except for parabolan, are 17-alkylated. Alkylated drugs are actively destroyed by the liver, and these drugs have a short half-life. 3-4 to 11-12 hours. The half-life varies greatly depending on how active your liver is. Accordingly, oral preparations require more frequent administration. This is usually 2-4 doses per day.

Despite the suitability of all 17-a alkylated preparations for oral administration, some of them are produced both in the form of tablets and in the form of suspensions (suspended crystals in water). For example, injectable methane or injectable stanozolol. Such suspensions act, as a rule, stronger than the oral form, and have a local effect. That is, they can stimulate stronger growth of muscle tissue at the site of administration. This is due to the creation there of a higher concentration of the active substance.


  1. Anabolic steroids are sex hormones modified to enhance their anabolic properties and prolong their action.
  2. Take steroids should be no less than 1 time per half-life.
  3. To extend the life of steroids, esterification or alkylation is used. Esterification – the conversion of a steroid into a salt, an ester of an organic acid. It does not change the action of the hormone on the body, but only stretches the release of the drug into the blood for a longer time. Alkylation is the addition of a CH4 molecule to a hormone molecule. It makes the drug suitable for oral administration. Alkylation at the 17th position enhances the anabolic effect of the drug.
  4. Steroid esters are a solution in oil for injections and, as a rule, last longer than the tablet form of anabolic steroids.