A comparative study of the CYP450 inhibition potential of marketed drugs using two fluorescence based assay platforms routinely used in the pharmaceutical industry.

Semi-automated high throughput screening for the inhibition of major human cytochrome P450 enzymes (1A2, 2C9, 2C19, 2D6 and 3A4) expressed in Escherichia Coli (Cypex bactosomes) or human lymphoblastoid cells (Gentest cDNA microsomes) using fluorescent probes has been evaluated using 68 marketed drugs. In general lower IC50 values were obtained with Cypex bactosomes compared with Gentest cDNA microsomes. This could be due to use of higherconcentration of protein and also the lower activity of Gentest cDNA microsomes.