Mixed normal micelle

Mixed Normal Micelles Effects on Reaction Rates... 

The absorption of vitamin E is relatively poor - only some 20% to 40% of a test dose is normally absorbed from the small intestine, in mixed lipid micelles with other dietary lipids. This absorption is enhanced by medium-chain triglycerides and inhibited by polyunsaturated fatty acids, possibly because of chemical interactions between tocopherols and polyunsaturated fatty acids or their peroxidation products in the intestinal lumen. Esters are hydrolyzed in the intestinal lumen hy pancreatic esterase and also by intracellular esterases in the mucosal cells. 

The book first discusses the structural and chemical properties of micelles and the role of thennodynamics, concentration, and additives in fonning micelles. Demonstrating how intcrmolecular forces influence the reaction mechanisms, the author presents kinetic models for reactions catalyzed by normal micelles, as well as mixed micelles and metallomicelles. The book also compares various types of catalytic reactions with and without micelles to quantify their effect on reaction rates and rate constants. Using this information, it illustrates how micelles can modify reaction rates and improve catalytic efficiency, particularly for industrial processes. The final chapter explains the principles of kinetics used for data analysis. 

To this point, only models based on the pseudo—phase separation model have been discussed. Mixed micelle models utilizing the mass action model may be necessary for micelles with small aggregation numbers, as demonstrated by Kamrath and Franses ( ). However, even for large micelles, the fundamental basis for the pseudophase separation model needs to be examined. In micelles, how much solvent or how many counterions (bound or in the electrical double layer) should be included in the micellar pseudo-phase is unclear. The difficulty is normally surmounted by assuming that the pseudo—phase consists of only the surfactant components i.e., solvent or counterions are ignored. The validity of treating the micelle on a surfactant—oniy basis has not been verified. Funasaki and Hada (22) have questioned the thermodynamic consistency of such an approach. 

Muranishi, S., N. Muranishi, and H. Sezaki. 1979. Improvement of absolute bioavailability of normally poorly absorbed drugs Inducement of the intestinal absorption of streptomycin and gentamicin by lipid-bile salt mixed micelles in rat and rabbit. Int J Pharm 2 101. 

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