Effects of ondansetron on symptoms during a gastric emptying study and enteral lipid challenge and on daily symptoms in diabetic gastroenteropathy

Background: This study compared the effects of ondansetron and placebo in patients with diabetes mellitus and symptoms of dyspepsia (diabetic gastroenteropathy [DGE]). Methods: We performed a randomized, double-blinded, placebo-controlled study of ondansetron tablets (8 mg) three times daily for 4 weeks in DGE patients. Symptoms were assessed with the Gastroparesis Cardinal Symptom Index daily diaries. Gastric emptying (GE) of solids (scintigraphy) and duodenal lipid infusions (300 kcal over 2 h) were each assessed twice, with placebo and ondansetron. Drug effects on GE, symptoms during the GE study and during lipid infusion, and daily symptoms were analyzed. Key Results: Of 41 patients, 37 completed both GE studies and one completed 1; 31 completed both lipid infusions and four only placebo; and all 35 randomized patients completed 4 weeks of treatment. Compared to placebo, ondansetron reduced the severity of fullness (p = 0.02) and belching (p = 0.049) during lipid infusion but did not affect GE T_1/2. Both ondansetron and placebo improved daily symptoms versus the baseline period (p < 0.05), but the differences were not significant. In the analysis of covariance of daily symptoms during the treatment period, the interaction term between treatment and the acute effect of ondansetron on symptoms during lipid challenge was significant (p =.024). Conclusions & Inferences: Ondansetron significantly reduced fullness during enteral lipid infusion in patients with DGE. Overall, ondansetron did not improve daily symptoms versus placebo. But patients in whom ondansetron improved symptoms during enteral lipid challenge were perhaps more likely to experience symptom relief during daily treatment.