Pharmacological study of prokinetic property of ondansetron, a novel 5HT3 receptor antagonist

ABSTRACT

This study was carried out to investigate the prokinetic property to ondansetron, a 5HT3 receptor antagontis, in vitro. The results showed that, ondansetron is potent 5HT3-receptor antagonist as it blocked 5HT induced chronotropic and inotropic effect in isolated rabbit heart whereas, methysergide didn't. Also, it produced a significant rightward shift of 5HT cumulative concentration curve in isolated guinea pig ileum. Prokinetic activity of the studied drug was demonstrated and assessed on the basis of its ability to enhance intestinal contractions which were blocked after atropine in isolated rabbit jejunum. In addition, it produced a significant leftward shift of Ach. concentration response curve in isolated guinea pig ileum. Moreover, it significantly potentiated the contractions evoked by high concentrations of 5HT in isolated guinea pig ileum. A clearcut evidence for the prokinetic property of ondansetron was observed as it stimulated rat fundal strip contractions which were completely abolished by atropine. Furthermore, it produced a significant leftward shift of cumulative 5HT concentration response curve in isolated rat fundus