FIRST DAY EFFECTS OF RABEPRAZOLE ON NOCTURNAL ESOPHAGEAL AND REGIONAL INTRAGASTRIC PH

Abstract

Purpose: Proton pump inhibitors decrease gastric acid secretion, increase intragastric pH and relieve symptoms of gastroesophageal reflux disease (GERD). Many patients with acid/peptic disorders, such as GERD, are symptomatic at night. AIM: 1) Determine the effects of rabeprazole on nocturnal esophageal and intragastric pH profiles on the first and eighth day of treatment. 2) Correlate the effects on intragastric pH with serum gastrin concentration. Methods: Ten normal subjects underwent two eight-day treatment sessions with morning placebo or rabeprazole 20 mg qd, in a randomized double-blind cross-over study design separated by 2 week washout period. Esophagogas-tric pH monitoring studies were performed on days 1 and 8 of each treatment. Esophageal pH was measured 2 cm above the LES and gastric pH at 7, 12, and 17 cm distal to the esophageal pH probe. Fasting blood sample was obtained for serum gastrin measurement on the morning after each 24 hour recording. Results: During the first night (midnight to 8 am) after placebo administration, the median gastric pH was 1.3 ± 0.2, without significant regional differences. Rabeprazole significantly increased the gastric pH on the first night of administration to 3.5 ± 0.6; p <0.01). On the eighth night of administration, rabeprazole continued to increase gastric pH to 3.9 ± 0.6 (p <0.01) compared to placebo. There was a slight, but significant, increase in serum gastrin from 42 ± 6 with placebo to 85 ± 28 pg/ml on day 1 and 62 ± 8 pg/ml on day 8 of rabeprazole administration. The distal gastric pH correlated with the serum gastrin level (r = 0.423; p = 0.009). Conclusions: Rabeprazole, at 20 mg po qd, significantly elevated nocturnal gastric pH on the first day of treatment to levels that are sustained for the first week. There were no regional intragastric differences in rabeprazole's action in increasing nocturnal intragastric pH. The increase in gastric pH with rabeprazole is associated with an acute doubling (day 1) and a small rise in serum gastrin at day 8.