Carrier lipophilic-hydrophilic balance

The process of reabsorption depends on the lipophilic-hydrophilic balance of the molecule. Charged and ionized molecules are reabsorbed slowly or not at all. Reabsorption of acidic and basic metabolites is pH-dependent, an important property in detoxification processes in drug poisoning. Both passive and active carrier-mediated mechanisms contribute to tubular drug ieabsorplion. 

Flavourings consist of a blend of flavouring substances, which can be classified as lipophilic or hydrophilic. Fat or oil serves as carrier of lipophilic, and water as carrier of hydrophilic substances. Tab. 5.4 shows the variation in odour threshold values of selected flavouring substances when placed in water vs. oil. Due to these great variations, reduction in fat levels of foods will affect not only the intensity of the flavour but also its balance, since only little or no carrier system is available for lipophilic flavour components in water. The lipophilic part of the flavour cannot be retained in the food matrix and is released immediately. Fat-reduced or fat-free foods show high flavour impact initially which dissipates quickly, while full fat products gradually build up intensity and dissipate more slowly (schematically depicted in Fig. 5.25). 

The other components of the carrier include surfactants and disinte-grants. Surfactants with a hydrophile-lipophile balance (HLB) value between about 10 and 25 are preferred. In some cases, the carrier is completely eliminated or added in small quantities to facilitate rapid release of the drug (Table 7.3). 

Nakashio et al. reported the use of lipophilic dialkyIdimethlylammonium bromides as surfactants in the formation of emulsion liquid membrane systems (22). The two long alkyl chains provided a good hydrophilicity-lipophilicity balance (HLB) to form a stable emulsion membrane. This finding led us to attempt the use of such quaternary ammonium salts in an emulsion liquid membrane system for which the ammonium salt functions not only as the emulsifying agent but also as the carrier for heavy metal halide complexes (Figure 5). 

Previously the possibility of using Sc, Sm, and Nd mono- and diphosphorylated amines 1-3 as membrane carriers in conditions of active transport with use of 1,2-dichlorobenzene as a membrane solvent has been shown. At the same time, a high rate of transmembrane transfer of ions Sc and Nd N,N-bis(dihexyl phosphoryl methyl) octyl amine (1) was set. In this paper, the new results of research of membrane transport properties of 1-3 carriers, by symport mechanism are described, and in this case the environmentally acceptable solvent—kerosene as a membrane phase was used. Besides that the membrane-transport properties of diphosphorilamine 4, that have not been described previously containing simultaneously highly lipophilic methyl dioctyl phosphorylic and practically hydrophilic 0,0-diethyl ethyl phosphonate groups in a molecule was studied. It is well-known that creation of optimal hydrophilic-lipophilic balance is a precondition of transmembrane transport effectiveness with organophosphorous carriers. ... 

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