Pharmacodynamics is a branch of pharmacology and its teaching deals with the biological effect of a drug on the organism. This includes the analysis of mechanisms of action, side effects, the dose and its effect, and toxicology.
What is pharmacodynamics?
Pharmacodynamics is a branch of pharmacology and its teaching deals with the biological effect of a drug on the organism. The administration of a drug, pharmacon, has certain effects on the physical organism. A drug substance enters into a connection with a receptor, thus an effect is triggered and an effect is achieved. The task of pharmacodynamics is to study these mechanisms of action for their biochemical and physiological effects. Which organs are affected, which biological functions are affected? Targets of a medication are enzymes, transport proteins embedded in the cell membrane, ion channels and receptors. Preference is given to synaptic connections located between the nerve fiber end and the organ in question. There are several mechanisms of action. The three most important include interfering with biosynthesis in microorganisms, inhibiting or activating enzymes, and affecting cell membranes to control metabolic processes.
Function, action, and targets
How a drug acts is closely related to the interaction between the active ingredient and its receptor, because the action of a pharmaceutical is tied to specific functional structures, and dependent on the molecular structure. Similar compounds react with comparable effects due to their analogous structure. The spatial arrangement of atoms in the molecule can also be a decisive factor. The receptors are cell structures. These are biologically active points in the organism, such as certain molecules or molecular particles on cell membranes. The basis of almost all drug effects is based on five mechanisms of action. These include interaction with receptors that can trigger either stimulation or blockade in the organism. If the enzyme activity is influenced, this can result in both activation and inhibition. Enzymes act as regulators. For example, if the enzyme is inhibited in the production of cholesterol, the cholesterol in the blood decreases. When ion channels are opened or blocked, for example, the calcium concentration can be reduced, which lowers the heart load. And when agents influence transport systems, the proton-potassium pump can be throttled, suppressing hydrochloric acid production in the stomach. Inhibition of biosyntheses in microorganisms is used to fight infections. As a result, penicillin is able to prevent the formation of a cell wall from bacteria. Drug substances thus enter into an important fusion with a receptor in order to specifically combat disease. Through this fusion, both an effect is triggered and an effect is achieved. The dose and its effect on the target site play a significant role in the use of a pharmaceutical. When does which effect appear, how long does it last, when does it end? As soon as a certain dose of the active substance shows an effect, we speak of a so-called threshold dose, an introductory dose. In order to produce a more rapid effect and thus a stronger effect, the dose is increased. But the increase cannot be arbitrary without generating disadvantages. A double dose in no way means a double effect. And after a certain amount, the maximum achievable reaction by the active drug substance has occurred. After that, no further increase can be expected. On the contrary, negative effects may even occur. That is why it is important to check at which doses which effects occur and how strong the effects are at which dose, and when they may have a toxic effect. Most active ingredients are specific, i.e. they develop their efficacy at a specific site. Non-specific drugs, on the other hand, spread throughout the entire organism. Therefore, the weight of a patient is decisive for the effect of such a substance. A patient weighing 100 kilograms requires a higher dosage than a patient weighing 80 kilograms. With specific active ingredients, on the other hand, weight plays a subordinate role, since the substance acts directly at the target site. Most drug substances have a specific effect.This means that only low dosages are required, which act at precisely defined target sites. The few non-specific active substances require high dosages to achieve an effect. With so-called active ingredient designs, the properties of a substance can be specifically adapted. In addition, there are active ingredients that combine several effects. These can be both effects and side effects.
Special features
The goal of a drug substance is the most specific influence possible to contain a disease on the spot. This rarely succeeds, so in addition to the desired, there are also undesirable effects, the side effects that are listed in the package inserts of drugs. Both effects, the desired and the undesired, depend on many factors. These include the dosage of the active ingredient, disease, age and sex of the patient; duration of treatment, sensitivity of the patient. The side effects can be harmless, but they can also have serious consequences. They range from loss of appetite to diarrhea, kidney damage, malformations in newborns, impaired driving ability or functional disorders. Cytostatic drugs have a non-specific effect and therefore have wide-ranging side effects such as nausea, vomiting and changes in the bone marrow due to reduced blood formation. It also becomes problematic for patients who have to take several drugs. This often leads to interactions that weaken, strengthen or even cancel out the individual drugs. In addition, the mechanism of action of many drugs is not yet clear.
