Effects of Ondansetron on Gastric Tone and Motility Changes Induced by a Prolonged Intraduodenal Infusion of Nutrients. Results of a Placebo-Controlled Study

Our aim was to study the 5-HT3 antagonist, ondansetron, on gastric motility changes induced by duodenal infusion of nutrients. First, the effects of a 2-hr intraduodenal infusion (IDI) of a caloric diet on antral motility were assessed. Second, a crossed-over placebo-controlled study assessed 3-day oral intake of ondansetron (8 mg bid) on gastric motility changes induced by the IDI. During the IDI, antral numbers of waves (NW) as area under curve (AUC) were lower than fasting values. After infusion, antral NW and AUC increased to return to basal values. The antral area increased slightly shortly after the start of the IDI, then remained stable. When subjects received ondansetron, the only significant motor effect was a higher antral NW and AUC during the first 30 min of the IDI (P < 0.05). After the end of the IDI, the AUC and NW increased in both the distal and the proximal antrum. The increase was lower by ondansetron in the proximal antrum. Proximal stomach relaxation induced was not influenced by ondansetron. In conclusion, an IDI of nutrients decreased antral motility, increased the antral area, and promoted fundic relaxation. This inhibitory effect was rapidly reversible. Ondansetron induced only minor motility changes in the antrum and had no effect on fundic relaxation promoted by IDI.