Comparison of gastrointestinal pH in cystic fibrosis and healthy subjects

Abstract

The primary objective of this study was to define the pH conditions under which supplemental pancreatic enzyme preparations must function in the upper gastrointestinal tract. The hypothesis was that normal or greater acid output in patients with cystic fibrosis (CF), combined with low pancreatic bicarbonate output, results in an acidic duodenal pH, compromising both dosage-form performance and enzyme activity. Gastrointestinal pH profiles were obtained in 10 CF and 10 healthy volunteers under fasting and postprandial conditions. A radiotelemetric monitoring method, the Heidelberg capsule, was used to continuously monitor pH. Postprandial duodenal pH was lower in CF than in healthy subjects, especially in the first postprandial hour (mean time greater than pH 6 was 5 min in CF, 11 min in healthy subjects, P less than 0.05). Based on the dissolution pH profiles of current enteric-coated pancreatic enzyme products, the duodenal postprandial pH in CF subjects may be too acidic to permit rapid dissolution of current enteric-coated dosage forms. However, the pH was above 4 more than 90% of the time on the average, suggesting that irreversible lipase inactivation in the duodenum is not likely to be a significant limitation to enzyme efficacy. Overall results suggest that slow dissolution of pH-sensitive coatings, rather than enzyme inactivation, may contribute to the failure of enteric-coated enzyme supplements to normalize fat absorption.

Wireless Telemetry and Cystic Fibrosis: Just the pHacts

“…Moreover, it helps confirm the findings of Youngberg et al published in the journal in 1987. At that time, Youngberg et al showed delayed attainment of pH 5.5 or pH 6.0 in CF subjects compared with healthy controls [3]. Also since this study was performed prior to the availability of proton pump inhibitors (PPIs), the qualitative similarity of the data to that of Gelfond et al supports the present studies assessment that PPI discontinuation in the CF subjects did not materially affect the data.…”

Physicochemical and Physiological Mechanisms for the Effects of Food on Drug Absorption: The Role of Lipids and pH

“…These data indicate that a brief period of elevated duodenal pH occurs upon ingestion of the meal that can be attributed to the cephalic phase of pancreatic bicarbonate secretion. 194 When considered in an overall context, the pH in the postprandial phase in the duodenum is lower than that in the fasted state.…”

Small-intestinal abnormalities in cystic fibrosis patients

“…Hoogeveen et al [51] demonstrated two CFTR-candidate proteins of 155 and 195 kDa, respectively. In the small intestinal enterocytes, the 155 kDa protein is predominantly localised in the rough endoplasmic reticulum membrane of the mucus secreting cells.…”

“…No significant differences in basal or postmilk responses of plasma gastrin could be detected [1]. Continuous radiotelemetric monitoring of duodenal pH shows that postprandial duodenal pH is lower in CF than in healthy subjects [51].…”