Rapid determination of tacrine and other drug metabolites in microsomal incubate by newly developed targeting algorithm on UHPLC/TOFMS

A rapid simultaneous determination method for in vitro Cytochrome P450 (CYP) activity assay of 1,2,3,4-tetrahydroacridin-9-amine (tacrine) metabolites using ultra high performance liquid chromatography (UHPLC) coupled with computer-assisted in-source collision induced dissociation (CID) monitoring was investigated. In general, enzyme inhibition assays require quantitative analysis of incubates with drugs using various concentrations of substrates/inhibitors. The assay of CYP isozyme inhibition is an important informational step in the drug discovery process and, with the many substrates listed by the FDA, high-throughput qualitative and quantitative analyses are desired. Based on sub-2-micron packing material with reversed phase chromatography combined with a single liquid chromatography/time-of-flight mass spectrometry (LC/TOFMS), a less than 1 min analysis time is presented for two additional drugs. We successfully determined seven of the eight potential isomer metabolites for the drug tacrine in 2.5 min using a 2 mm internal diameter × 100 mm length column and applying in-source CID with our newly developed chromatographic peak deconvolution technique. Although two of the peaks were heavily fused at a peak width of less than 300 ms, we could clearly identify these peaks by monitoring the chromatographic intensity difference of their fragment peaks on the mass spectrum.