Gastrointestinal pH

Drug Interactions During Absorption Changes In Gastrointestinal pH... 

Dressman. Comparison of gastrointestinal pH in cystic fibrosis and healthy subjects. Dig. Dis. Sci. 1987,... 

Sasaki, Y., Hada, R., Nakajima, H., Fukuda, S., Munakata, A., Improved localizing method of radiopill in measurement of entire gastrointestinal pH profiles colonic luminal pH in normal subjects and patients with Crohn s disease, Am. J. Gastroenterol. 1997, 92, 114-118. 

Changes in gastrointestinal pH Antacids, histamine H2-receptor antagonists and proton pump inhibitors reduce the absorption of... 

Species differences in absorption may occur for any of the following reasons differences in gastrointestinal pH or anatomy, differences in rate of blood flow to the absorption site, differences in breathing rate, differences in skin type, and the presence or absence of fur. 

Russell, T.L., et al. 1993. Upper gastrointestinal pH in seventy-nine healthy, elderly, North American men and women. Pharm Res 10 187. 

Evans, D.F., et al. 1988. Measurement of gastrointestinal pH profiles in normal ambulant human subjects. Gut 29 1035. 

Mojaverian P (1996) Evaluation of gastrointestinal pH and gastric residence time via the Heidelberg Radiotelemetry Capsule Pharmacological application. Drug Development Research 38 73-85... 

Very few data are available on gastrointestinal pH in children. In 12 healthy subjects aged 8-14 years, the mean gastric pH was 1.5 and duodenal pH was 6.4, but this gradually rose in the small intestine reaching a peak value of 7.4 in the distal ileum.The pH dropped to 5.9 as the pH radiotelemetry capsule entered the caecum but increased to 6.5 in the rectum. The median gastric residence time of the telemetry capsule was 1.1 h, small intestinal transit time was 7.5 h, and colonic transit time was 17.2 h. 

Dantas, R.O. Dodds, W.J. Measurement of gastrointestinal ph and regional transit times in normal children. J. Pediatr. Gastroenterol. Nutr. 1990,11 (2), 211-214. 

Little information is available about the structure of degradation products formed in neutral or acid solution or in the solid state. The penicilloic acid and small amounts of penicillamine (VIII, R=H) and a pyrazine (assumed to be IX, R=CH3, but see below) were found [30] under gastrointestinal pH conditions, 1.5 increased stepwise to 8. A small amount of N-formylpenicillamine (VIII, R=CHO) was formed at pH 7 [51]. 

The observation that iron absorption is reduced when gastric acid secretion is compromised (14) suggests that gastrointestinal pH does influence food iron availability. The explanation for this appears to be related to the importance of acid for the release of iron from food. Bezwoda et al. (15) measured the capacity to solubilize iron in bread of gastric juice from normal and iron deficient subjects. Gastric juices with pH values above 2 had limited capacity to solubilize bread iron while below pH 2, solubilization of iron increased linearly with decreasing pH. 

Youngberg, C., Berardi, R., Howatt, W., Hyneck, M., Amidon, G Meyer, J. and Dressman, J. (1987) Comparison of gastrointestinal pH in cystic fibrosis and healthy subjects. Digestive Diseases and Sciences, 32 (5), 472-480. 

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