Acute Effects of the 5-Hydroxytryptamine Type 4 Receptor Agonist Mosapride on Pharyngeal Swallowing Physiology in Adults.

The 5-hydroxytryptamine type 4 receptor agonist mosapride is known to modulate esophageal peristalsis and enhance lower esophageal sphincter compliance. However, its impact on oropharyngeal swallowing physiology remains insufficiently characterized. This study aimed to investigate the acute effects of mosapride on oropharyngeal swallowing dynamics in adults. Participants received either oral mosapride (40 mg) or placebo 1 h prior to testing in a randomized, crossover design. High-resolution impedance manometry was performed using a solid-state catheter to measure pressure and impedance within the oropharyngeal segment. Each participant underwent at least three swallows of 5, 10, and 20 mL thin and thick liquids administered by syringe. Manometric data were analyzed using the Swallow Gateway web-based platform. Twenty-four volunteers (13 male, mean age, 33 years; range, 24-56 years) completed the study. During thick swallows, mosapride significantly increased upper esophageal sphincter (UES) maximal opening admittance compared to placebo (5 mL: p = 0.017; 10 mL: p = 0.008) and reduced UES integrated relaxation pressure (10 mL: p = 0.018; 20 mL: p = 0.017). No significant effects were observed during thin liquid swallows. A marginal reduction in pre-deglutitive UES basal pressure was noted during 5 mL thick swallows (p = 0.050). Following adjustment using repeated measures ANOVA, only the reduction in UES basal pressure remained statistically significant (p = 0.040). Acute administration of oral mosapride results in reduced UES basal tone in adults. These findings provide novel physiological evidence suggesting that mosapride may modulate neuroregulatory mechanisms controlling UES contractility.