7-Ethoxy (OEt) coumarin has been used as a model substrate in many cyto-chrome P450 (P450) studies, including the use of kinetic isotope effects to probe facets of P450 kinetics. P450s 1A2 and 2E1 are known to be the major catalysts of 7-OEt coumarinO-deethylation in human liver micro-somes.