Effect of omeprazole on intragastric and duodenal bulb acidity in duodenal ulcer patients.

Intraluminal pH was measured simultaneously in the stomach and duodenal bulb with six small, glass electrodes tied together at 1.5-cm intervals. Ten patients with duodenal ulcer disease were studied under fasting conditions and for 3 h after a standard liquid meal on three occasions: day 1, before treatment; day 8, when the proton pump blocker omeprazole had been taken in a daily dose of 30 mg for 7 days consecutively, including the day of the pH study; day 9, 24 h after the last dose of omeprazole. Mean hydrogen ion activity and the percentage of time with pH below 3 was calculated from the digital pH data sampled at a frequency of 1 per second from each electrode. On day 8, five of the patients were permanently anacidic (pH greater than 4) in the stomach and duodenum, while the food-stimulation broke off anacidity for shorter periods in the other five patients. The pH pattern in the duodenal bulb was markedly altered in all patients with disappearance of the typical pH fluctuations, and a decrease in the time that the pH was below 3 from a median value of 30% before treatment to 0% in seven patients and close to 0% in three patients. On day 9, a large patient-to-patient variation was observed in gastric pH: three patients were still anacidic, four were markedly suppressed, but three patients reached near pre-treatment acidity. Duodenal bulb acidity was still decreased significantly on day 9 in all patients, with post-prandial pH below 3 for less than 5% of the time, compared with 30% before treatment.