Pharmacology

In this paper, the topics of general pharmacology, special pharmacology and toxicology will be explored. To understand pharmacology sufficiently, however, one must possess basic notions of physiology, biochemistry, human anatomy and pathology.

Pharmacology is a branch of biological disciplines that has as its study target the effects produced by various substances introduced into the human organism, but also into the animal one. The substances examined, including drugs, can induce both beneficial and harmful effects The beneficial effects are achieved with the administration of these substances within certain therapeutic doses, but if these dosages are exceeded, the effect received can be harmful to our system. A separate discussion is made for poisons, because they are substances that always cause, and at any dose, a harmful / toxic effect.

The drug

Previously we mentioned and did not explain what a drug is. There are two definitions that describe the drug substance. The first definition given by the WHO (World Health Organization) says that a drug is any substance or product used to explore or modify physiological or pathological systems, therefore for therapeutic or diagnostic purposes, to the benefit of the recipient. The drug must be introduced into the organism and modify one or more functions; if this does not happen, the therapeutic effect received from this substance cannot be exploited.

In the second definition given by the EEC (European Economic Community), in addition to the definition of drug seen above, the concept of prophylaxis is also introduced. So we mention not only the substance for curative-therapeutic-diagnostic purposes, but also the product that is administered to prevent the onset of certain pathologies (for example, before a surgery an antibiotic prophylaxis is implemented to protect our body from any bacterial contamination).

Classification of drugs

Based on the type of induced pharmacological action, drugs are classified into:

Symptomatic: act on the symptoms of the disease (flu).
Causal or etiological: they act on the cause of the disease (antibiotics).
Pathogenetic: they act on the mechanisms of the disease (antihypertensive, antiarrhythmic).
Substitutes: they restore functions of the organism altered by the disease (insulin).

General pharmacology and special pharmacology

Pharmacology can be divided into general and special pharmacology.

The general pharmacology includes PHARMACOKINETICS and PHARMACODYNAMICS. The first studies the events to which a drug is subjected when it comes into contact with our body (absorption, distribution, metabolism and excretion) and thanks to this knowledge it is able to determine the dosage of the drug. The second studies the mechanisms of action of the drug itself (drug-receptor interaction or other mechanisms).

Special pharmacology studies the various classes of drugs.

Stages of the action of a drug

Pharmaceutical phase: characterized by pharmaceutical availability, i.e. the ability of the pharmaceutical form (capsules, tablets, suppositories, solutions, aerosols ...) to release the active ingredient so that it is absorbed and subjected to pharmacokinetic processes.

Pharmacokinetic phase: it depends on the chemical and physico-chemical characteristics of the drug and includes a series of processes that determine the amount of drug available at the site of action.

Pharmacodynamic phase: it consists of the interaction of the drug or one of its active metabolites with the site of action (receptor macromolecule), which in turn activates the biological response.

General Pharmacology

Let's start now with the first part of general pharmacology, in particular with pharmacokinetics:

science that studies the movement of a drug within the body.

Before reaching all the actions that are part of pharmacokinetics, the active principle must be introduced into our body through the main routes of administration. The active principle cannot be taken as such but must be combined with excipients, thus forming a pharmaceutical form.

The pharmaceutical form can be of different types such as a syrup, a capsule, a tablet, a suspension, a patch, etc. At this point, once introduced or applied in the case of the patches, the pharmaceutical form undergoes modifications that allow the release of the active ingredient (pharmaceutical phase). The active principle, made available, can therefore undergo all the pharmacokinetic processes, such as absorption, distribution, metabolism and elimination. In addition to the latter, the drug also undergoes pharmacodynamic processes with possible interactions with receptors or with certain mechanisms, thus producing the much desired pharmacological effect.