Granisetron selectively blocks serotonin 5-HT 3 receptors located at the end of the vagus nerve and in the trigger zone of the bottom of the fourth ventricle of the brain (practically does not affect other serotonin receptors). Granisetron is well absorbed in the digestive tract (if there is no vomiting). Associated with plasma proteins by 65%.
In the liver, granisetron undergoes N-demethylation and oxidation of the aromatic ring, after which it conjugates. The resulting metabolites have antiserotonin activity. T 1/2 granisetron in oral and / in the introduction of 9 hours, with a wide individual variability. The main route of granisetron excretion is with the bile, about 12% (after i.v. administration) is excreted in the urine within 48 hours.
Granisetron eliminates vomiting that occurs when the parasympathetic nervous system is excited due to the release of serotonin from enterochromaffin cells.