Determination of in vitro permeability of drug candidates through a Caco-2cell monolayer by liquid chromatography/tandem mass spectrometry

Studying the permeability of compounds across a Caco-2 cell monolayer is an established in vitro model to screen for oral absorption and to evaluate t he mechanism of transport. This assay can also be used to evaluate compound s as potential P-glycoprotein substrates and/or inhibitors. The traditional methods of sample analysis (high-performance liquid chromatography (HPLC) with a UV or fluorescence detector) limit the throughput and sensitivity of this assay. Data are presented here describing the use of liquid chromatog raphy/tandem mass spectrometry (LC/MS/MS) for the analysis of samples deriv ed from the Caco-2 cell studies. During the analysis an automatic switching valve was used to divert the flow from the HPLC column to waste for the fi rst minute, preventing the early eluting salts from entering and contaminat ing the LC/MS interface. This approach allows the rapid and accurate determ ination of drug transport across the Caco-2 cell monolayer, The high sensit ivity and specificity of LC/MS/MS make this technique an ideal candidate fo r the low concentration and high throughput routine analysis of Caco-2 cell solutions, especially if multiple compounds are administered and analyzed simultaneously. Thus, the use of LC/MS/MS will increase the value of the Ca co-2 cell assay as an ill vitro screening tool. Copyright (C) 2000 John Wil ey & Sons, Ltd.