Caco-2 Cells as an Absorption Model

Caco-2 cells, especially the human intestinal epithelial cell line, have been proposed and used for the simulation and prediction of intestinal drug absorption after oral administration. These membranes of cells have useful properties for correlation with in vivo data such as enzymatic and transporter systems [24]. 

As permeability is a function of lipophilicity, molecular size, H-bonding capacity, and charge, and as charge is included in lipophilicity (log P) when the distribution 

Antibiotic Route of administration Human oral bioavailability (%)a P app h (cm/s) x KT66 

The effect of size and charge on the passive diffusion of peptides across Caco-2 cell monolayers via paracellular pathways as well as on retention time has been studied using the IAM technique [38]. It was found that a positive net charge of the hydrophilic peptides favors permeation across the intestinal mucosa via the paracellular pathway. With an increase in size, the molecular sieving of the epithelial membrane dominates the transport of peptides and the influence of the net charge becomes less important. The permeability coefficient, Papp, of the capped amino acids and the model peptides can be calculated by  

02 M phosphate buffer, pH 7.4, and an immobilized artificial membrane of PC analogs. 

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