Pharmacology of ondansetron.
Ondansetron is a highly potent and selective antagonist at 5-HT3 receptors. Its anti-emetic actions were first revealed by its ability to antagonize retching and vomiting induced by chemotherapy and radiotherapy in animals and man. Subsequently, the availability of labelled 5-HT3 receptor ligands allowed identification of 5-HT3 receptors, located at highest densities in the area postrema, nucleus tractus solitarius (NTS), in other areas of the brain, and on afferent terminals of the vagus nerve. Postoperative nausea and vomiting may be caused by various factors: the anaesthetic, associated drugs, the surgical procedure, movement of the patient, sex, weight and pain. These factors mediate their effects via the higher brain circuits, the vestibular nuclei, the chemoreceptor trigger zone in the area postrema, or the upper gastrointestinal tract via the vagus nerve, influencing motor and visceral emetic outputs in the hind-brain. It is hypothesized that ondansetron blocks nausea and vomiting by 5-HT3 receptor antagonism at two specific sites: (i) centrally, in the area postrema/NTS; and (ii) peripherally on vagus nerve terminals. The absence of other pharmacological effects of ondansetron ensures an absence of side-effects.
Naylor
R J
RJ
School of Pharmacy, University of Bradford, West Yorkshire, UK.
Rudd
J A
JA
D000818:Animals; D006801:Humans; D009325:Nausea / Q000517:prevention & control; D017294:Ondansetron / Q000494:pharmacology*; D011183:Postoperative Complications / Q000517:prevention & control; D014839:Vomiting / Q000517:prevention & control
D017294:Ondansetron