[An outline of 5-HT3 receptor antagonists (1)--In pharmacological actions].

This paper described an outline of pharmacological studies of 5-HT3 receptor antagonists, mainly on ondansetron, which control nausea and vomiting associated with cancer chemotherapy. Administration of cytotoxic drugs is known to increase serotonin (5-HT) concentrations, and when released, 5-HT provokes the emetic responses via two routes; 1) 5-HT acts as an intrinsic transmitter substance and stimulates the emetic response via 5-HT3 receptors on vagal afferent terminals; 2) 5-HT transmits impulses to the vomiting center via 5-HT3 receptors on the chemoreceptor trigger zone in the area postrema of the central nervous system. 5-HT3 receptor antagonists are thought to exert an antiemetic action by specifically and competitively blocking 5-HT3 receptors.