TABLE 1

Inhibition of dextromethorphan O-demethylation by cimetidine and quinidine Pooled human liver microsomes (HLM; 0.5 mg of protein/ml) or recombinant CYP2D6 (rCYP2D6; 2.5 pmol/ml) were incubated with NADPH (1 mM) and various concentrations of DEX and cimetidine or quinidine, and K_i values were determined as described under Materials and Methods. Data are expressed as the mean ± S.D. of three independent determinations.