[Use of antihistamines in a physician's clinical practice].

Histamine that belongs to one of the most important mediators involved in the regulation of the body's vital functions plays a great role in the pathogenesis of different diseases. Histamine is released during inflammatory and allergic reactions, anaphylactic and anaphylactoid shock, pseudoallergic reactions, and others. Acting through histamine receptors, it leads to increased intracellular concentration of cyclic guanosine monophosphate, enhanced chemotaxis of eosinophils and neutrophils, production of prostaglandins and thromboxane B, suppressed synthesis of lymphokines, etc. and causes contraction of smooth muscles of particularly the bronchi and intestine, dilation of vessels and their increased permeability, mucus hypersecretion in the upper airways, lower blood pressure, angioedema and itch, etc. In this connection, antihistamines that block histamine-induced reactions in various ways: by inhibiting its biosynthesis, enhancing its neutralization, blocking the access to receptors, and suppressing the release from mast cells, occupy a prominent place in clinical practice. The review covers the classification, main mechanisms of pharmacological action, and indications for the use of antihistamines that not only have the well-known antihistamine properties, but have also a broad spectrum of anti-inflammatory activity. There are data on the benefits of a group of antihistamines, the quinuclidine derivatives (quifenadine, sequifenadine) that were designed by Academician M.D. Mashkovsky and are one of the first examples of designing new classes of multifunctional non-sedating antihistamines, which combines a high selective activity to block histamine type 1 receptors and an ability to block serotonin and to break down histamine directly in tissues.