Effect of the non-ionic surfactant Poloxamer 188 on passive permeability of poorly soluble drugs across Caco-2 cell monolayers

Drug permeability of the model drugs ketoprofen and nadolol across Caco-2 cell monolayers was determined in the absence and presence of the non-ionic surfactant Poloxamer 188 (Pluronic® F68, P-188). Stringent controls confirmed that P-188 in concentrations up to 50 mg/ml did not adversely affect cell viability or monolayer integrity. Equilibrium experiments confirmed that the drugs were merely passively transported. Caco-2 permeability of both drugs was found to be decreased by the surfactant in a concentration-dependent manner. Ultrafiltration revealed that both drugs were associated with surfactant micelles. The systematic investigation of micellization on passive absorption showed that association of drugs with P-188 micelles appears to depress their passive permeability under conditions where other transport mechanisms can be neglected.

We found that the permeability in Caco-2 monolayers was depressed in the presence of Poloxamer 188 micelles in a concentration-dependent way, when other than the passive pathway could be excluded. These findings corrobate the theory that the micelle associated drug is not readily absorbed, but that only the free drug is.Figure optionsDownload as PowerPoint slide