RT Journal Article SR Electronic T1 Effect of Common Organic Solvents on in VitroCytochrome P450-Mediated Metabolic Activities in Human Liver Microsomes JF Drug Metabolism and Disposition JO Drug Metab Dispos FD American Society for Pharmacology and Experimental Therapeutics SP 1 OP 4 VO 26 IS 1 A1 Chauret, Nathalie A1 Gauthier, Annick A1 Nicoll-Griffith, Deborah A. YR 1998 UL http://dmd.aspetjournals.org/content/26/1/1.abstract AB In this study, we report the effect of methanol, dimethyl sulfoxide (DMSO), and acetonitrile on the cytochrome P450 (P450)-mediated metabolism of several substrates in human liver microsomes: phenacetinO-deethylation for P4501A2, coumarin 7-hydroxylation for P4502A6, tolbutamide hydroxylation for P4502C8/2C9,S-mephenytoin 4′-hydroxylation for P4502C19, dextromethorphan O-demethylation for P4502D6, chlorzoxazone 6-hydroxylation for P4502E1, and testosterone 6β-hydroxylation for P4503A4. DMSO was found to inhibit several P450-mediated reactions (2C8/2C9, 2C19, 2E1, and 3A4) even at low concentrations (0.2%). There was no measurable effect on the catalytic activity of the various P450s when methanol was present at levels ≤1%, except for P4502C8/9 and 2E1. Acetonitrile did not noticeably change the catalytic activity of the P4502C8/2C9, 2C19, 2D6, and 2E1 enzymes at concentrations ≤1%. It was found that the content level of the organic solvents should be kept lower than 1% because, for all three solvents, a concentration of 5% strongly affected the metabolism of the various probes. These findings should be taken into consideration when designing in vitrometabolism studies of new chemical entities. The American Society for Pharmacology and Experimental Therapeutics