Effect of Omeprazole on Regional and Temporal Variations in Intragastric Acidity

Abstract

Background: Conventional techniques for measuring gastric acidity have demonstrated the decrease in gastric acidity produced by proton pump inhibitors (PPI); however, such techniques do not detect transient or localized pH changes which may modify the intragastric environment without affecting the therapeutic efficacy of PPIs. Aim: To investigate local and temporal variations in intragastric pH and to test the hypothesis that omeprazole produces prolonged, generalized gastric anacidity (pH >6). Methods: A single-blind study was conducted with triple-point 24-hour gastric pH-metry on days 7, 14 and 21 in 14 healthy, Helicobacter pylori-negative volunteers (7 M; 20–46 years) who received placebo for 7 days, followed by omeprazole 20 mg daily for 14 days. Results: Omeprazole increased the median 24-hour pH significantly in the distal corpus (placebo: 1.3 (95% CI 1.1 to 1.6); omeprazole week 1: 4.0 (2.6–5.0); omeprazole week 2: 4.0 (2.8–4.6)) and at all other gastric recording sites (p < 0.01). At both corpus sites, nocturnal pH was lower and mealtime pH was higher than the non-meal daytime pH during placebo and both omeprazole administration periods; in the antrum, however, the major difference noted was that meal-time pH was higher than non-meal daytime pH. Antral pH was lower during meals and higher at night than proximal corpus pH. During placebo, gastric pH >6.0 was observed at 1 site only for 1.7% (median; 95% CI 0.4–3.3%), at 2 sites simultaneously for 0.24% (0.0–1.0%) and at 3 sites for 0.0% (0.0–0.28%), respectively, of the recording periods; during the second week of omeprazole, the equivalent results were 7.7% (1.4–14.0%), 4.9% (0.21–15.7%) and 4.7% (0.0–9.9%), respectively. Conclusions: Omeprazole, 20 mg daily, does not produce gastric anacidity despite significant increases in median 24-hour pH values. The time-, meal- and site-related variations in gastric pH observed under normal physiological conditions are seen to persist, with prolonged periods of low pH throughout the stomach and preservation of the normal, meal-related rise and nocturnal fall in gastric pH during omeprazole administration.

The binding selectivity of vonoprazan (TAK‐438) to the gastric H+,K+‐ATPase

“…Hence, about one‐third of the pumps are synthesised in 24 h, so that even with twice a day treatment, newly synthesised pumps will be secreting acid before the next administration of a PPI. This makes control of night‐time acid secretion difficult …”

Foraging mode, relative prey size and diet breadth: A phylogenetically explicit analysis of snake feeding ecology

“…Rather this seems to be a trait common to a diversity of reptiles (Coulson, Hernandez, & Dessauer, ; Fox & Musacchia, ; Skoczylas, ; Wright, Florey, & Sanders, ) and so would also be expected in actively foraging snakes. The contrasting condition in mammals, which maintain their pH levels in the stomach between meals (Viani et al., ), appears to be evolutionary conserved rather than a response to foraging mode.…”

Gastric function and its contribution to the postprandial metabolic response of the Burmese pythonPython molurus

“…In contrast to the slight alkalinity of the fasting python's stomach, mammals maintain a highly acidic environment (pH 1.1-3) within their stomachs between bouts of digestion (Youngberg et al, 1985;Evans et al, 1988;Cilluffo et al, 1990;Viani et al, 2002). Whereas pythons experience a dramatic postprandial decrease in gastric pH, the luminal pH of mammal stomachs increases rapidly after feeding to range between 3 and 6, presumably as the ingested meal buffers the gastric acid (Savarino et al, 1988;McLauchlan et al, 1989;Cilluffo et al, 1990).…”