This Article Full Text (PDF) All Versions of this Article: 1087057105285612v1 11/3/303    most recent References Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Hummel, M. A. Articles by Rock, D. A. Search for Related Content PubMed PubMed Citation Articles by Hummel, M. A. Articles by Rock, D. A. Social Bookmarking                   What's this?

Influence of Fluorescent Probe Size and Cytochrome b5 on Drug-Drug Interactions in CYP2C9

Timothy S. Tracy

Department of Experimental and Clinical Pharmacology, University of Minnesota, Minneapolis

J. Matthew Hutzler

Jan L. Wahlstrom

Yihong Zhou

Dan A. Rock

Pharmacokinetics, Dynamics and Metabolism, Pfizer Global Research & Development, St. Louis Laboratories, Pfizer Inc., St. Louis, Missouri

7-Methoxy-4-trifluoromethylcoumarin (MFC) has been used extensively in high-throughput screens for the identification of potential CYP2C9 interactions. More recently, additional probes from Invitrogen have been used. Vivid 2C9Green is the largest of the probes and has had limited prior characterization. The newseries of probes differ significantly from MFC andwere examined for their ability to identify interactions with 19 CYP2C9 substrates/inhibitors. The inhibition profiles depend largely on the physical differences between the fluorescent probe substrates. Cytochrome b5 (cyt b5) was also investigated for the ability to alter the inhibition profile of a given compound. The stoichiometric addition of cyt b5 caused an increase in Vmaxof MFC and Vivid 2C9 Green 4.4 and 1.7 times, respectively. Furthermore, cyt b5 imposes a steric component to the active site as the inhibition profiles were significantly affected in incubations with MFC. The addition of cyt b5 had limited impact on the inhibition profiles generated with Vivid 2C9Green. The K_m of Vivid 2C9 Green increased from 1.2 ± 0.2 µ Mto4.8 ± 0.3 µ Mas a result of cyt b5 addition. These results illustrate that multiple substrate probes may be necessary for screening drug-drug interaction in CYP2C9 and that cyt b5 effects can impart steric restraints on the CYP2C9 active site.

Key Words: CYP2C9 • drug interactions • fluorescent • inhibition • cytochrome b5

CiteULike    Connotea    Del.icio.us    Digg    Reddit    Technorati    What's this?