Determination of in vitro permeability of drug candidates through a caco-2 cell 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 the mechanism of transport. This assay can also be used to evaluate compounds 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 chromatography/tandem mass spectrometry (LC/MS/MS) for the analysis of samples derived 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 first minute, preventing the early eluting salts from entering and contaminating the LC/MS interface. This approach allows the rapid and accurate determination of drug transport across the Caco-2 cell monolayer. The high sensitivity and specificity of LC/MS/MS make this technique an ideal candidate for 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 Caco-2 cell assay as an in vitro screening tool. Copyright 2000 John Wiley & Sons, Ltd.