antidote(redirected from antidotal)
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a medicine used to cure poisoning. Antidotes counteract poisons and prevent or eliminate the toxic effects caused by them. Antidotes are applied before absorption of the poison (local-acting antidotes) or after its entry into the bloodstream (resorptive antidotes). The first group includes substances that counteract poisons in the stomach, on the skin, and on the mucous membranes before their absorption and entry into the organs and tissues (active charcoal and alkalines in cases of acid poisoning, and so on). The antidotal effect is achieved by means of the physical-chemical (absorption) and chemical (oxidation, neutralization, formation of insoluble salts) interaction of this group of substances with the poison. The second group of antidotes is composed of substances counteracting poisons in the blood and organs. The antidotal effect is achieved both by interaction with the poison circulating in the blood and by a direct “displacement” of the poison from the tissues of the organism in accordance with the principle of concentration gradients. Antidotes of this type include unitiol, the British Anti-Lewisite (BAL) and the similar Hungarian dikaptol, Czechoslovak dimerkaprol, and German (GDR) Dithio-glycerine, which counteract compounds of mercury, chrome, arsenic, and other metals (except lead), whose effect is due mainly to the presence in them of molecules of the sulf-hydryl (SH) groups; oximes, which reactivate the enzyme cholinesterase, which is blocked in cases of organic phosphorous poisoning; preparations of ethylenediaminetetra-acetic acid (EDTA), which forms complexes with the salts of heavy metals that are eliminated relatively quickly in the urine; and several others.
Antidotes that act in a functional manner contrary to that of a particular poison play an important role. Thus, the antidote of muscarine, physiostigmine, and other substances causing acute excitation of the cholinergic systems of the organism is atropine, which blocks these systems.
Together with antidotes, many medicines that eliminate individual symptoms of poisoning and substances that promote the expulsion of poison from the organism (emetics, laxatives, and diuretics) are used. These means are widely used in treatment of poisoning; however, in the strict sense of the word they are not antidotes.
An antidote must be applied as quickly as possible after the entry of poison into the organism. The introduction of an antidote does not exclude a whole series of general precautions, such as washing out of the stomach, blood transfusions, or artificial respiration.
REFERENCESKarasik, V. M. “Protivoiadiia.” In Rukovodstvo po farmakologii. Edited by N. V. Lazarev. Vol. 2. Moscow, 1961. Pages 436–51.
Golikov, S. N. lady i protivoiadiia. Moscow, 1968.
Ludevig, R., and K. Lohs. Akute Vergiftungen, 2nd ed. Stuttgart, 1968.
S. N. GOLIKOV