Modulation of the postprandial acid and bile pockets at the gastro-oesophageal junction by drugs that affect gastric motility

P>Background Previous studies have established the presence of a postprandial acid pocket at the gastro-oesophageal junction. Aims To investigate whether altering gastric motility would affect the location and the extent of postprandial acid pockets in healthy volunteers and also to study the presence of bile in this pocket. Methods A total of 16 healthy volunteers underwent pH and Bilitec probe stepwise pull-through to measure regional differences in pH and bile absorbance before and 10, 30 and 50 min after a liquid meal. At the start of the meal, saline, erythromycin or sumatriptan was administered. Results After saline, ingestion of a meal induced an acid pocket, with a mean pH drop of 2.26 (compared to 0.25 before the meal, P < 0.05) and a nadir pH of 2.71. The acid pocket persisted 30 and 50 min postprandially (pH drops 1.59 and 1.68 and nadir pH 3.17 and 2.52 respectively). Compared with saline, erythromycin significantly suppressed the pH drop and nadir pH (on average 0.66 and 3.4 at 10 min; comparable patterns at 30 and 50 min). After sumatriptan a significantly lower nadir pH was observed at 30 and 50 min (respectively 2.02 and 1.74, P < 0.05 compared with saline). A postprandial bile pocket was noted in 50% of pull-throughs after saline, compared to 78% after erythromycin and 31% after sumatriptan. Conclusions The presence of a bile pocket in a subset of the subjects confirms the heterogeneity of postprandial intragastric contents. Erythromycin disrupts the acid pocket but increases the presence of bile, while sumatriptan has opposite effects.