A Glass of Water Immediately Increases Gastric pH in Healthy Subjects

Onset of action of antisecretory agents is of pivotal importance for patients with gastroesophageal reflux disease (GERD) treated "on-demand." Aim To study the acute effect of acid-inhibiting drugs and water administration on gastric pH. Method A cross-over study was performed in 12 H. pylori (-), healthy subjects (6 men; mean age: 26 years). A single oral dose of the following agents was received with a wash-out period between each study: a glass of water (200 ml), antacid, ranitidine, omeprazole, esomeprazole, and rabeprazole. Gastric pH was recorded for 6 h after drug intake. Results Water increased gastric pH > 4 in 10/12 subjects after 1 min. The time (median) needed to pH > 4 was for: antacid 2 min, ranitidine 50 min, omeprazole 171 min, esomeprazole 151 min, and rabeprazole 175 min. Gastric pH > 4 lasted for 3 min after water and for 12 min after antacids; it remained > 4 until the end of recording in: 4/12 subjects with ranitidine, 11/12 with rabeprazole, and all with omeprazole and esomeprazole. Conclusion Water and antacid immediately increased gastric pH, while PPIs showed a delayed but prolonged effect compared to ranitidine.