Small intestine absorption

JN Cogburn, MG Donovan, CS Schasteen. A model of human small intestinal absorptive cells. 1. Transport barrier. Pharm Res 9 210-216, 1991. 

Yee, S., In vitro permeability across Caco-2 cells (colonic) can predict in vivo (small intestinal) absorption in man - Fact or myth Pharm. Res. 

Gramatte, T., el Desoky, E., Klotz, U., Site-dependent small intestinal absorption of ranitidine, Eur. J. Clin. Pharmacol. 1994, 46, 253-259. 

The gastrointestinal system of zebrafish presents clear differences from the human system. The zebrafish does not possess a stomach, the intestine is continuous with the pharynx through a short esophagus, and no sphincters are present [61]. However, zebrafish have most of the cell types observed in the small intestine -absorptive, endocrine, goblet, and interstitial cells of Cajal, although Paneth cells are absent. Gut contractions are under the control of the enteric nervous systems, which respond to different pharmaceuticals in similar way as the mammalian counterpart. For example, zebrafish embryos can be used as predictor of emetic response to pharmaceuticals, one of the most commonly reported clinical adverse effects to be considered in the development of new dmgs [61]. 

Toyobuku, H., Tamai, 1., Ueno, K. and Tsuji, A. (2003) Limited influence of P-glycoprotein on small-intestinal absorption of cilostazol, a high absorptive permeability drug. Journal of Pharmaceutical Sciences, 92, 2249-2259. 

Pharmacokinetics Moderately absorbed from the small intestine (absorption depends on presence of vitamin D metabolites and patient s pH). Primarily eliminated in feces. 

Yata N, Sugihara N, Yamajo R, et al. Enhanced small intestinal absorption of P-lactam antibiotics in rats in presence of monodesmosides from pericaps of Sapindus mukurossi (Ennmei-hi). J Pharmacobio-Dyn 1986 9 211-217. 

Although unformulated 5-ASA is readily absorbed from the small intestine, absorption of 5-ASA from the colon is extremely low. In contrast, approximately 20-30% of 5-ASA from current oral mesalamine formulations is systemically absorbed in the small intestine. Absorbed 5-ASA undergoes /V-acetylation in the gut epithelium and liver to a metabolite that does not possess significant anti-inflammatory activity. The acetylated metabolite is excreted by the kidneys. 

It is absorbed into the blood through the cells lining the stomach and the small intestine. Absorption requires passage through the plasma membrane, the rate of which is determined by the polarity of the molecule charged and highly polar molecules pass slowly, whereas neutral hydrophobic ones pass rapidly. The pH of the stomach contents is about 1.5, and the pH of the contents of the small intestine is about 6. Is more aspirin absorbed into the bloodstream from the stomach or from the small intestine Clearly justify your choice. 

Tokunaga, Y., S. Muranishi, and H. Sezaki. 1978. Enhanced intestinal permeability to macromolecules. I. Effect of monoolein-bile salts mixed micelles on the small intestinal absorption of heparin. J Pharmacobiodyn 1 28. 

Hence, even without the larger surface area of the small intestine, acidic substances would be absorbed much more readily from the small intestine than the large intestine, because they are less dissociated in the small intestine. The opposite is true for basic substances. While acidic substances are less dissociated in the stomach than in the small intestine, absorption is greater in the small intestine because of the much larger surface area. 

Due to its compartmental nature, the CAT model can be easily coupled with the disposition of drug in the body using classical pharmacokinetic modeling. In this respect the CAT model has been used to interpret the saturable small-intestinal absorption of cefatrizine in humans [175]. 

It has been shown that log/tiAM values showed good correlation with skin penetration, stratum corneum membrane permeability ]56], blood-brain barrier distribution ]57,58], CaCOi cell permeability, and rat small intestinal absorption ]53]. The correlations... 

Figure 48-3 The location of small intestinal absorption. (Modified from Morris JA, Se//vonozK S/ie/don GE Nutritional management of patients with malabsorption syndrome. Clin Gastroenterol l983 l2 463-74, based on Borgstrom 8, et al. Studies of intestinal digestion and absorption in the human, j Clin Invest I957 I52I 36.)...

Yee S. In Vitro Permeability Across Caco-2 cells (colonic) can Predict in vivo (small intestine) Absorption in Man - Fact or Wyth.Pharm Res 1997 14 763-766. 

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