Vomiof

Ondansetron is a selective serotonin 5-HT3 receptor antagonist. The serotonin 5-HT3 receptors are located on the nerve terminals of the vagus in the periphery and centrally in the chemoreceptor trigger zone of the area postrema. It is thought that chemotherapeutic agents produce nausea and vomiting by releasing serotonin from the enterochromaffin cells of the small intestine, and that the released serotonin then activates 5-HT3 receptors located on vagal efferents to initiate the vomiting reflex. Therefore Ondansetron works by blocking the reception of serotonin at these 5-HT3 receptors.