The effects of omeprazole on intragastric pH, intestinal motility, and gastric emptying rate

Background: The present study was designed to investigate whether omeprazol e changes the characteristics and thereby the functions ascribed to fasting intestinal motility, postprandial motility, postprandial pH, and gastric e mptying. Methods: Ten healthy subjects were investigated. The studies were performed after 10 days of treatment with 40 mg omeprazole daily/placebo. D uodenal pressures and intragastric pH were detected by strain-gauge transdu cers and a pH electrode attached to a miniature computer. The meal consiste d of an omelette labelled with Tc-99m-sulphur colloids followed by 150 ml w ater labelled with In-111-diethylenetriamine pentaacetic acid. Results: The difference in fasting intragastric pH between the two series was highly si gnificant. The profile from the placebo series showed a relationship betwee n phase activity and pH. The pH increased from phase I (median, 1.3; 95% co nfidence interval (Cn, 0.9-1.6) to a maximum at 25% (1.8 (0.9-2.1)) and 50% (1.6 (1.1-3.8)) of cycle duration and decreased thereafter until the end o f the cycle. The profile from the omeprazole series showed significantly hi gher values during the entire cycle but no relationship between phase activ ity and pH. Pretreatment with omeprazole was followed by a delay in gastric emptying of liquid at 30 min (64% (49%-66%) (omeprazole series) versus 78% (67%-83%); P < 0.01) and solid at 180 min (71% (48%-86% (omeprazole series ) versus 96% (87%-100%); P < 0.01). There was no significant difference in duration of postprandial motility (305 min (157-350 min) (omeprazole) versu s 259 min (129-403 min)). Conclusions: Omeprazole eliminates the temporal r elationship between intragastric pH and characteristics of the migrating mo tor complex and induces a delay in gastric emptying of both liquid and soli d. A non-significant increase in duration of postprandial motility may repr esent a type-II error.