Pharmacokinetics and Pharmacodynamics of a drug are the essential parameters, necessary to be understood before you start taking it. Pharmacodynamics refers to ‘what a drug does to our body’. The term pharmacokinetics means ‘study of what an organism does to the drug’ i.e. the movement of the drug inside our body starting from its absorption, digestion, metabolism, and excretion, ultimately leading to the removal of a drug from the body after it has performed its function. Both of these mechanisms are important for knowing the drug dose, its effects, and side-effects.
Understanding the half-life of a drug is a major part of its pharmacokinetics. Half-life means the time taken by the body to remove half of the concentration of the drug, originally administered. It can be of minutes or can last up to hours, all depending on the processes working inside the body. Some drugs are metabolized faster than others. If one understands the half-life of a drug, he /she would be able to take more accurate doses and attain desirable and efficient results. The frequency of uptake and its detectability levels, all depends on the half-life of the drug.
The half-life of steroids may vary hugely. The half-life calculations vary at different bodybuilding websites, and most of these numbers are not verified scientifically. These may even differ between individuals depending on their practices. These values are very important for any bodybuilder or physique-yearning athlete because this shows how to manage and organize the dosage cycle aptly, the time-duration of its administration for safer effects. It is vital to know when the drug reaches its optimal blood plasma levels or one can term it as ‘Steady-state’ conditions because this is the point when the actual gains kick in with lesser side-effects. The drug’s half-life also matters because of the withdrawal symptoms it may cause. The small is the half-life, the severe would be the withdrawal symptoms and vice-e-versa.
What determines the Steroidal half-lives?
The steroidal half-life depends upon route the f administration, chemical modifications, and metabolism by the liver. There are two routes of administration i.e. Oral and Injectable administration. Other routes like Transdermal patches, creams or gels are also available. The half-life of injectable forms of the drug is more than the oral forms of the drug. The oral drug encounters first pass elimination in the liver, but it does not slow down the release of hormones in the blood. The half-life ranges from 4-48 hours. Injectable forms are of two types; oil-based drugs and water-based suspensions. Both of these forms are injected into the muscles and sits there for a longer time because of the slow rate of dispersion and entering the blood stream. Half-life can be from 24 hours to about 15 days. Chemical modifications like esterification even enhance the half-life more, making it fat-soluble and its dispersion slower. Also, if the drug shows more resistance to its metabolism by the liver, then again the half-life is increased.
Half-life values are no fixed figures. These are just approximations. Understanding the half-life will make steroid administration easy.