Characterization of cytochrome P450 (CYP) 2D6 drugs as substrates of human organic cation transporters and multidrug and toxin extrusion proteins.

Some drugs that are substrates of CYP2D6 are also substrates of OCTs and MATE1, suggesting overlapping specificities. Variability in sparteine hydroxylation in extensive and intermediate metabolizers cannot be explained by OCT1 genetic variants indicating presence of other factors. Dose-dependent toxicities of dextromethorphan, diphenhydramine and perhexiline appear to be independent from OCTs and MATEs.