PHARMACODYNAMICS OF CYTISINE
Cytisine is an agonist of the cholinoreceptors in the vegetative ganglia
and belongs to the group of the gangliostimulating drugs. It excites the
nicotine-sensitive cholinoreceptors of the postsynaptic membranes in the
vegetative ganglia, chromaffin cells in the molecular part of the
suprarenal gland and sinocarotid reflexogenic zone, which results in
excitation of the respiratory center, predominantly through the reflexes,
simulation of adrenaline release by the medullar part of the suprarenal
glands and a rise in the blood pressure. After its absorption in the
gastrointestinal tract, cytisine plays the part of a nicotine-substitute
substance which decreases the period of interaction between nicotine and
the corresponding receptors. This in turn leads to a gradual decrease and
interruption of the smokers' psychic and physical nicotine dependence.
Many researchers confirm in different pharmacological experiments the
similarity between the pharmacological properties of cytisine and
nicotine, as described by Dale & Laidlaw (1912) and confirmed also by
the conclusions of Zachowsky (1937), Anichkov (1937), Dobrev and Paskov
(1953), Daleva (1963), etc., in whose opinion cytisine is more potent as a
gangliostimulating than as a ganglioblocking agent.
Fig. 3 Mechanism of action of cytisine. Creation of the vicious cycle of tabacisme and the way to exit frmo it by means of Tabex
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This similarity between the peripheral effects of cytisine and
nicotine is more quantitative than qualitative. Comparable effects of
both drugs have been obtained in experiments on cats and rats (studies
on the blood pressure), or on guinea-pig ileum and rat diaphragm, the
doses of cytisine being 1/4 to 2/3 from the nicotine dose.
As regards the effects on the central nervous system, cytisine has a
weaker effect on the respiration of anesthetized rabbits, compared to
the effects on the peripheral nervous system.