Description of the medicine: Histamine (Histaminum)

HISTAMINE (Histaminum). 4- (2-Aminoethyl) -imidazole, or b-imidazolyl-ethylamine.

Histamine is a biogenic compound formed in the body by decarboxylation of the amino acid histidine.

Histamine is one of the endogenous factors (mediators) involved in the regulation of vital body functions and plays an important role in the pathogenesis of a number of disease states.

Under normal conditions, histamine is in the body mainly in a bound, inactive state. With various pathological processes (anaphylactic shock, burns, frostbites, hay fever, hives and other allergic diseases), and also when certain chemicals enter the body, the amount of free histamine increases. "Liberators" ("liberators") of histamine are d-tubocurarine, morphine, iodine-containing radiopaque preparations, high-molecular compounds (polyglucin, etc.) and other drugs.

Free histamine has a high activity: it causes spasm of smooth muscles (including the muscles of the bronchi), dilated capillaries and lowering blood pressure; Stagnation of blood in the capillaries and an increase in the permeability of their walls causes swelling of the surrounding tissues and thickening of the blood. In connection with the reflex excitation of the adrenal medulla, adrenaline is released, arterioles narrow and cardiac contractions increase. Histamine causes increased secretion of gastric juice.

Some amounts of histamine are contained in the central nervous system, where it is supposed to play the role of a neurotransmitter (or neuromodulator). It is possible that the sedative effect of some lipophilic histamine antagonists (antihistamines penetrating the blood-brain barrier, for example, dimedrol) is associated with their blocking effect on central histamine receptors.

In the body, there are specific receptors for which histamine is a natural ligand. At present, three subgroups of histamine (H) receptors are distinguished: H 1 -, H 2 - and H 3 -receptors.

Excitation of peripheral H, -receptors is accompanied by spastic reduction of bronchi, intestinal muscles and other phenomena.

The most characteristic for the excitation of H 2 -receptors is increased secretion of the gastric glands. They are also involved in the regulation of the tone of the smooth muscles of the uterus, intestines, vessels. Together with H 1 -receptors, H 2 -receptors play a role in the development of allergic and immune reactions.

H 2 -receptors are also involved in excitation mediation in the CNS. Recently, the importance of stimulating H3 receptors in the mechanism of the central action of histamine began to attach great importance.

As a medicine, histamine is of limited use.

For medical use, the preparation is prepared by bacterial cleavage of histidine or synthetically.

It is available as a dihydrochloride (Histamini dihydrochloridum).