A comparison of the permeation enhancement potential of simple bile salt and mixed bile salt:fatty acid micellar systems using the CaCo-2 cell culture model

Abstract

The aim of this study was to compare the permeation enhancing potential and toxicity of simple bile salt and bile salt:fatty acid mixed micellar systems using the CaCo-2 cell culture model. The effects of micellar systems of sodium cholate, (NaC), and sodium taurocholate, (NaTC), on the permeability of the hydrophilic markers, mannitol (182) and polyethylene glycols (PEGS) 900 and 4000, were assessed. Simple micelle systems of the unconjugated bile salt, NaC, caused greater enhancement of the hydrophilic markers than the conjugated bile salt, NaTC. In the case of NaC systems the enhancement was coincident with excess membrane disruption and toxicity as indicated by altered TEERs, TEMs, MTT values, and, the lack of recovery following removal of the enhancer. In contrast, the NaTC systems were less toxic, and, in the simple micelle form the likely mechanism of enhancement of the hydrophilic markers is via a transient effect on the tight junctions. Formation of mixed micellar systems with linoleic acid (LA) accentuated the toxic effects of NaC. In comparison, NaTC:LA mixed micelles showed superior permeability enhancement versus simple micelles without increasing membrane toxicity. The mechanism of enhancement of NaTC:LA appears more complex and involves a possible combination effect on both the paracellular and transcellular routes.