The article will consider two similar concepts - pharmacokinetics and pharmacodynamics. Maximum attention will be paid to the latter phenomenon, since it is of greater interest.
Does everyone correctly understand the role of pharmacology in the modern world? Very often it seems that this is a rather undervalued industry that is paid little attention to. But modern man can not do without it. Diseases, stresses and frequent depressive conditions greatly affect human health. That is why you have to resort to the help of drugs or doctors. In any case, it concerns pharmacology. But today we will talk about a very close, but still different concept, which is quite interesting if you consider it from different points of view.
What is it about?
Pharmacodynamics is one of the branches of pharmacology that deals with the issues of the effectiveness of a complex of drugs, the mechanism of their effect on humans, and some of the relationships that are manifested in the amount of drug use and the effect obtained.
Study methods
Pharmacodynamics is an industry that can be studied using certain methods. Specific methods are too complex and scientific, so we will not delve into complex professional terms, but only consider the key properties that each method should possess:
- increased sensitivity, which means the ability to show large deviations from the initial state in the case of directional exposure, which allows you to record the positive dynamics of changes;
- increased specificity, which means the ability of an object to very rarely give false positive results;
- reproducibility, which means the ability to regularly reflect the characteristics of patients in the same conditions and with repeated studies, even if any dynamics in the state according to clinical data is completely absent.
Pharmacodynamics of therapeutic agents
It’s worth mentioning right away that the vast majority of drugs can exert their therapeutic effect, because they can affect the physiological systems of cells. Not everyone understands the simple truth, but drugs, acting on the human body and bringing a certain result, in no way change the type of work of the cells. The change lies only in the fact that the rate of reactions is changing. The pharmacodynamics of therapeutic agents is such that, when exposed, physiological processes are inhibited or stimulated, which leads to a decrease or increase in certain conditions in humans. This is what is called the medicinal effect.
In addition, therapeutic agents can have a significant and not always positive effect on enzymes, cell substances, membranes, or receptors. Experimental pharmacodynamics is just the industry that is engaged in practical research on the effects of drugs on humans.
Specific receptors
Pharmacodynamics, the mechanism of action of which we are considering, has a wide area of influence. Now we will consider the effect on receptors, but first we need to figure out what it is. A receptor is a macromolecular structure that reacts incredibly sensitively to specific chemical compounds. Thanks to receptors, a person can receive sensations from the outside world. The clinical effect of the interaction of the receptor and the chemical compound is expressed in the fact that biochemical and physiological changes are provoked in the body.
Do you know about agonists? So called drugs that excite or greatly increase the activity of receptors. There are other substances - antagonists that block the effects of excitatory elements. It is interesting that the phenomenon of antagonism itself can be competitive and non-competitive. Once in the human body, the drug begins to "compete" with the natural regulator in the human body in order to replace its effect and get a key effect on certain receptors. It is possible to block the receptor with a competitive antagonist by increasing the dose of a drug or, for example, a natural regulator.
The mechanism of pharmacodynamics is complex and diverse, and even has not yet been fully studied. This is largely due to the fact that receptors can behave differently. By the way, they have different sensitivity. Each receptor is sensitive to a specific substance, and not to all at once. For example, let’s say that receptors that are especially sensitive to adrenaline are called adrenergic. The main difference that exists between the receptors of the whole organism is only that they are sensitive to different substances. There are different subtypes of receptors. In the case of adrenaline, these are dopamine, histamine, serototin, etc.
Enzymes
There is no definite classification of pharmacodynamics, because everything depends on the specific substance that affects the human body. The main and only classification is the type of system that a particular drug affects.
There are drugs that can increase or, conversely, reduce the activity of certain enzymes. For example, when a person has too frequent and abrupt excitement of the parasympathetic nervous system, he will be prescribed drugs that act on adrenaline and muffle the excitability of the parasympathetic nervous system, but stimulate the sympathetic.
Effects on cell membranes
The pharmacodynamics of drugs can affect muscle cells, cells of the nervous system, etc. The flow of ions, which determine the electrical potential, has the greatest influence on cell membranes. Special medicines are sometimes used that can alter the transport of ions. Based on this effect on the human body, general anesthesia drugs, anticonvulsants and antiarrhythmic drugs were developed.
Chemical exposure
Medicines can not only affect certain systems in the body, showing an increase or decrease in their activity, but also directly interact with some elements. These elements include a small part of ions and molecules. For example, we can take the process of neutralization with antacid hydrochloric acid preparations.
Dose and effect
The most important feature of pharmacodynamics is that there is a fundamental indicator, which is called the "dose-effect". In mathematical terms, it is a complex calculation. It can be graphically depicted in different ways: a curved curve, linearly, sigmoidally. Such a graphic image is due to the fact that each medicine in any case will have positive and negative moments of influence on the human body.
Most often, the effect goes up with increasing dose. But at the same time, side effects can very often occur. In the study of the drug, experts determine the therapeutic index of the drug, which sets the exact dose of the drug that is needed to produce the most beneficial effect.
Pharmacokinetics and pharmacodynamics are two important elements without which medicine medicines simply would not exist. You can invent a medicine, but how to determine the limits of its effectiveness? It is to these questions that pharmacodynamics answers, which allows us to draw a line beyond which undesirable side effects may occur.