N-in-one permeability studies of heterogeneous sets of compounds across Caco-2 cell monolayers.

PURPOSE: The purpose of the study was to evaluate several n-in-one cocktails of heterogeneous compounds to increase the throughput of permeability studies across Caco-2 monolayers, to investigate the reliability and applicability of the method, and to develop fast and sensitive analysis for the compounds. Compounds with potential interactions in efflux and/or active transport were chosen.
METHODS: Permeability experiments with verapamil, propranolol, midazolam, hydroxyzine, timolol, buspirone, procaine, naproxen, ketoprofen, and antipyrine as single compounds and in cocktails of 5-10 compounds were performed at 50 microM concentration both in the apical-to-basolateral and basolateral-to-apical direction. The compounds were quantified by liquid chromatography-electrospray tandem mass spectrometry (LC-ESI/MS/MS). Toxicity tests were performed to determine cellular damage.
RESULTS: The analytical method was sensitive, accurate, and rapid. The individual permeabilities of compounds in cocktails correlated well with permeabilities as single compounds. No significant interactions between the compounds within the mixtures were observed, except for acidic compounds. The studied mixtures did not show any toxicity.
CONCLUSIONS: The use of n-in-one cocktails is a suitable method to improve the capacity in routine permeability experiments and higher throughput screening of drug candidates, although potential interactions should always be borne in mind. The use of LC-ESI/MS/MS technology provides an excellent tool in fast and accurate analysis of small amounts of heterogeneous compounds.