1 December 2023

We may know little about the scientific discipline that investigates the different processes that occur in a body. This is known as physiology, an essential branch of medicine. Some of these processes can be triggered by the drugs we consume on a daily basis, as well as by harmful substances that should not enter our body. Therefore, I invite you to continue reading to delve into this matter.

Meaning of toxicokinetics

Toxicokinetics focuses on the study of how toxic substances enter the body, are distributed, metabolized, and eliminated. This process can be complex and requires analysis detailed to determine the stay of the substance in the body. The study of toxicokinetics involves various phases, including the absorption, distribution, metabolism, and elimination of the toxic substance. The metabolic reaction of the organism can be affected by the presence of the substance.

When a toxic substance enters the body, can trigger a series of phenomena that affect the body. To assess in detail the effects of toxic substances on the body, toxicokinetics uses a series of assessments. Previously, the study of the movement of chemists was limited to pharmaceuticals, but over time it expanded to include all related branches. Thus arose toxicokinetics and toxicodynamics.

Initially, early toxicology studies they focused on drugs, since it was essential to know how the body would react to their intake and the possible adverse reactions in case of high doses. As toxicology has evolved, it has included the investigation of environmental and occupational chemicals, such as drugs. Its scope covers all studies related to substances, including exposure levels and whether or not they are toxic.

What are the stages or phases of toxicokinetics?

Within this topic you can identify four fundamental processes to understand its operation. These processes are:

  • Absorption: It refers to the moment in which a substance enters the body. The speed of absorption can vary and depends on the type of absorption. There are two types of absorption kinetics: that of zero order, where the amount of substance absorbed is constant, and that of first order or exponential, where there is still substance to be absorbed.
  • Dispersion: in this case we refer to the process by which the substance is distributed from the point of entry to other parts of the body. Once in the bloodstream, it is transported through the tissues, and its distribution depends on factors such as irrigation and the partition coefficient. In some models, the dispersion of the substance occurs immediately through the body’s fluids and tissues, and changes in the concentration of the substance can be quantified. When dispersion processes are reversible and first order, drug diffusion follows Fick’s first law, which states that the flux is proportional to the concentration gradient.
  • Transformation: Once the substance enters the body, a biotransformation process occurs that converts to a water soluble compound which can be easily removed. During this process, new compounds called metabolites are formed.
  • Excretion: This is the final phase of the process, in which the components are removed from the body. The bodily secretions have the ability to excrete all chemicals. Studies have shown that toxic elements have also been found in sweat, tears, and saliva.

There are three main elimination pathways that occur by removing these compounds through digestion: urine, exhaled breath, and feces. In addition, they can also be eliminated through bile and breast milk.

What is the importance of toxicokinetics?

Toxicology provides us with a detailed understanding of the various stages involved in poisoning caused by toxic agents. Any substance, no matter how small, It is considered a poison but what makes the difference is the dose that is administered so that it becomes a remedy.

Thanks to the rigorous tests carried out in toxicology, a reliable evaluation of the chemical substances to be administered can be carried out, which facilitates selection of appropriate therapeutic interventions. The results obtained allow us to know both the active principle and the duration of the effects that a toxic agent can have.

The extension of toxicology allows a comprehensive evaluation of the substance before, during and after its passage through the body, as well as the effects it can cause in living organisms. Therefore, its inherent ability with respect to the chemical agent is of great importance.

What factors affect toxicokinetics?

There are several factors that can affect the phases of the poisoning process. For example, when a drug needs to be metabolized by the body to become active, blood esterase activity is a critical factor. In newborns and premature children, these enzymes may be reduced by 50-64% compared to adults.

During pregnancy, drug distribution may also be affected due to changes in extracellular water volume. Also to hormonal fluctuations that are produced, which can alter the clearance processes.

During fetal development, the maternal volume of distribution increases, as does the metabolic capacity of the mother and the placenta. Other factors, such as the menstrual cycle, the use of hormonal contraceptives, menopause and andropause can also alter the density of substances and affect the intoxication process.

Examples of the use of toxicokinetics

Toxicokinetics is a discipline that studies the different phases that lead to the intoxication of chemical agents in the human body. It is essential to estimate the rate of absorption, metabolism and elimination of these substances, as well as the degree of binding of transporter proteins.

This discipline It is commonly applied therapeutically. where body samples are taken to obtain sufficient scientific bases. One of the prominent examples is the interaction of xenobiotics with each other and with food.

Toxicokinetics is crucial in the administration of medicines, since it allows to control the corresponding doses and to anticipate possible side effects that may occur in the patient. Therefore, the study of it is of great importance for public health and safety in the use of chemical substances.

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