Analysis of native heme. CYP2D6 was treated with SCH 66712 (16 μM) in the presence or absence of NADPH for 0, 2, 5, 10, 15, and 40 min (only data for the 40-min incubation are shown). Heme content was analyzed by HPLC using absorbance at 405 nm. Native heme eluted at 22.5 min. After a 40-min incubation with SCH 66712 and NADPH (right panel), there was a 25% decrease in native heme compared with time 0 (left panel).