Lecture
In modern medicine, a large number of pharmaceutical preparations belonging to different classes of chemical compounds are used. In therapeutic doses, these preparations promote the restoration of body functions disturbed by disease. However, the same medicinal substances, under certain conditions
(excessive dose, changes in the reactivity of the organism, etc.), can also exert a
harmful effect on people and animals. The complex of pathological changes arising in the body under the influence of medicinal or other substances is called
poisoning, or intoxication, and the substances causing poisoning are called
poisons. Toxicology (from Greek toxikon – poison and logos – study) – the science
that studies the properties of toxic substances and the pathological changes in the body
caused by them. Toxicology also studies effective means of treating and
preventing poisonings.
Poisonings by toxic substances can be studied from the point of view of
their toxicodynamics and toxicokinetics.
The term toxicodynamics refers to the mechanism of action of toxic
substances in the body.
Toxicokinetics studies the processes occurring with toxic substances in the body (their absorption, distribution, transformation of toxic)
substances in the body, elimination from the body, etc.). Knowledge of the toxicokinetics
of poisons makes it possible to correctly choose the organs and biological fluids subject to chemico-toxicological examination, to correctly assess the results of chemico-toxicological analysis, and to resolve other important questions related to establishing the causes of poisonings.
Owing to the rapid development of chemistry and the constant improvement
of chemical technology, industry produces more and more chemical
compounds every year, which find use in various branches of the national economy.
Many of them are toxic. At present there are several classifications of poisonings,
which are based on taking into account:
- the features of the clinical course (acute and chronic);
- the causes of occurrence (accidental and intentional);
- the conditions of occurrence (domestic, occupational, etc.);
- the routes of entry into the body (oral, inhalational, etc.)
and so on. Acute poisonings occur as a result of exposure of the body to excessive
doses of poisonous substances. They are accompanied by rapidly increasing
symptoms and can end in death within several minutes
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(hydrocyanic acid and its salts), hours, or days. Intentional acute
poisonings for the purpose of murder (criminal) also occur. Toxic substances can be used for suicide (suicidal poisonings).
Also acute poisonings, the cause of which are errors of medical personnel or pharmacy workers.
Chronic poisonings are possible with repeated intake (over a
long period of time) of small doses of toxic substances, cumulated in the body,
not causing acute poisonings, but sufficient to impair one or another function of the body. Chronic poisonings are characterized by a slow
course and vaguely expressed symptoms.
Occupational poisonings are observed among workers of plants, factories, and chemical laboratories, where poisonous substances are produced or used.
substances
Domestic poisonings belong to the category of accidental poisonings. They arise as a result of careless storage and use of toxic substances
for household and domestic use (rodenticides,
insecticides, liquids for cleaning clothes, etc.).
Domestic poisonings include alcoholism and drug addiction. Alcoholism
– the systematic excessive consumption of alcoholic beverages in quantities that
cause alcohol intoxication. Drug addiction – a disease arising from the non-medical use of medicinal or other agents classified in the
established manner as narcotic.
Substance abuse – a disease caused by the abuse of certain substances or medicinal agents not included in the list of narcotics,
but the systematic use of which has a negative medical and social
significance. The cause of substance abuse may be abuse not only of
medicinal agents, but also of chemical substances that are not medicinal
preparations (technical fluids, household chemical products, plant parts,
etc.).
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