The control inhibitor (quinidine) and marker substrate (dextromethorphan or bufuralol) were transferred to the incubation vessels (60 μL aliquots each). After a pre-incubation period at 37° C., the reactions were initiated by the addition of a 40 μL aliquot of NADPH regenerating system (BD Gentest). A 40 μL aliquot (diluted 6:19 with incubation buffer) provided final concentrations of 1.3 mM NADP+, 3.3 mM glucose-6-phosphate and 0.4 U/mL glucose-6-phosphate dehydrogenase. Incubation times were 12 minutes for both dextromethorphan and bufuralol. Reactions were terminated by the direct addition of acetonitrile (160 μL) to the incubation mix followed by transfer to a pooling plate containing additional acetonitrile (400 μL).
