Passive Membrane Permeability and the Polar Surface Area

Let us conclude this section by proposing that provided that the drug is sufficiently soluble in the gastrointestinal fluids, the complex process of intestinal drug absorption can often be satisfactorily described by focusing on passive transport across the cell membrane, and that the development of models that predict passive transcellular permeability is particularly important. Such models are the focus of the remaining part of this chapter. 

Passive Membrane Permeability and the Polar Surface Area 

The application of a two-step partitioning process can be motivated if we consider the insertion of a polar, but lipophilic, molecule into a phospholipid membrane. In the first step, lipophilicity is the major driving force for drug incorpora- 

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Passive Membrane Permeability and the Polar Surface Area I 345... 

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