Transport and absorption

M Asgharnejad. Investigation into intestinal transport and absorption of an amino acid, amino acid analougue and its peptideomimetic prodrug. PhD dissertation, Chapter IV. pp 109-127, The University of Michigan, 1992. 

PXR CAR FXR LXR AhR 3A4 and others 2B, 2C, 3A4 7A 7A 1A1, 1A2, 1A6, 1B1, 2S1 Xenobiotic metabolism regulation, antioxidant Xenobiotic metabolism regulation Bile add metabolism and transport Reverse cholesterol transport and absorption Reproduction and development regulation... 

Models for Nasal Drug Transport and Absorption Studies... 

This chapter discusses the transport and absorption of ozone and other photochemical oxidants within the respiratory tract. It includes lung morphology and flow aspects of respiratory physiology and emphasizes methodologic approaches to modeling. 

In this section, sites of action in the respiratory tract are discussed, along with experimental studies of gas uptake in animals. Cumulative dose and dosage at critical sites of action are defined, as well as the general characteristics required for modeling the transport and absorption in the respiratory tract. 

The high water solubility of arbutln provides efficient leach-ablllty of the compound from plant tissues and subsequent transport and absorption by other plants. The ultimate chemical form (hydroqulnone vs. arbutln) available for absorption would be dependent upon the extent of decomposition (le. hydrolysis) affecting arbutln transport. 

Similarly, in RA, reactions occur simultaneously with the component transport and absorptive separation, in the same column zone. These processes are used predominantly for the production of basic chemicals, e.g., sulphuric or nitric acids, and for the removal of components from gas and liquid streams. This can be either the cleanup of process gas streams or the removal of toxic or harmful substances in flue gases. Absorbers or scrubbers where RA is performed are often considered gas-liquid reactors (10). If more attention is paid to the mass transport, these apparatuses are instead treated as absorption units. 

In vitro models have provided invaluable information about properties of compounds that affect their in vivo transport and absorption. Regardless of how closely in vitro systems model in vivo conditions, they cannot completely represent what may be seen in vivo by virtue of their reduced nature. For that reason, it is important to consider that a focused endpoint generated using an in vitro model will only correlate to a much more complex parameter like absorption when that endpoint is a major determinant of the complex parameter. The lack of in vitro/in vivo correlation does not necessarily implicate a failure of the model, but rather that the endpoint may not be sufficient to describe the in vivo process. Furthermore, the in vivo data used for these correlations are rarely... 

Compounds that show low but intrinsic absorption can be optimized by various galenic techniques and procedures. However, those which possess no absorption ability at all cannot be optimized by such procedures. New strategies have been developed for novel drag delivery systems to control drag release, transport, and absorption across mucosal membranes. A special class of modifiers are amphiphilic... 

Lin Y., Shen Q., Katsumi H., Okada N., Fujita T., Jiang X., Yamamoto A. (2007) Effects of Labrasol and Other Pharmaceutical Excipients on the Intestinal Transport and Absorption of Rhodaminel23, a P-Glycoprotein Substrate, in Rats. Biol Pharm Bull, 30(7) 1301-1307. 

The experimental animals were female albino rats, mostly five weeks old. Iron-manganese interaction was studied on the everted duodenal segment (77) where the transport and absorption of the two metals per unit of time are higher than in the more distal parts of the intestine (78-82). Manganese-54 and iron-59 were used as markers for their stable isotopes. 

Taurine is a rather specialized topic in the nutritional biochemistry of digestion. Taurine, 2 aminoethane sulfonic acid, is synthesized from cysteine, as shown in Figure 2AI). I hc taurine molecule contains an amino group as well as an acidic group. Taurine has not been found in proteins, although some evidence suggests that it occurs in certain polypeptides. Taurine t ccurs as a component of bile salts and plays an important role in the transport and absorption of lipids. 

An Overview ofCaco-2 and Alternatives for Prediction of Intestinal Drug Transport and Absorption... 

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