title: In vitro inhibition of cytochrome P450-mediated reactions by gemfibrozil, erythromycin, ciprofloxacin and fluoxetine in fish liver microsomes.
abstract: Inhibition of mammalian cytochrome P450 enzymes (CYPs) is well characterized; major hepatic CYPs can be inhibited by drugs and other environmental contaminants. CYP function and inhibition has not yet been well established in fish yet these studies are important for several reasons. First, such studies will provide functional information for non-mammalian CYPs. Second, specific inhibitors can be used as a diagnostic tool for studying CYP-mediated reactions. Lastly, pharmaceutical mixtures are found in the aquatic environment and adverse effects associated with drug-drug interactions, including CYP inhibition by pharmaceuticals may be of concern. Using liver microsomes from untreated and β-naphthoflavone (BNF)-treated rainbow trout, eight fluorescent CYP-mediated catalytic assays were used to assess in vitro CYP inhibition by four pharmaceuticals: fluoxetine, ciprofloxacin, gemfibrozil and erythromycin. Expressed zebrafish CYP1 proteins (CYP1A, CYP1B1, CYP1C1 and CYP1C2) were assessed for inhibition with selected substrates. All pharmaceuticals decreased the metabolism of a number of substrates. Fluoxetine was the strongest and most broad inhibitor of CYP-mediated reactions in liver microsomes. Zebrafish CYP1s were strongly inhibited by erythromycin and fluoxetine. Although the pharmaceuticals are selective CYP inhibitors in mammals, inhibition across a number of substrates suggests they are broad inhibitors in fish. These data demonstrate that in vitro hepatic CYP inhibition by pharmaceuticals is possible in fish and the patterns seen here are different than what would be expected based on CYP inhibition in mammals.
authors: Department of Biology, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4K1.
authors: Emily M
authors: EM
authors: Smith
authors: Fathima I
authors: FI
authors: Iftikar
authors: Sarah
authors: S
authors: Higgins
authors: Anam
authors: A
authors: Irshad
authors: Racquel
authors: R
authors: Jandoc
authors: Matthew
authors: M
authors: Lee
authors: Joanna Y
authors: JY
authors: Wilson
mesh_terms: D000818:Animals; D002939:Ciprofloxacin / Q000633:toxicity; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D004917:Erythromycin / Q000633:toxicity; D029941:Fish Proteins / Q000378:metabolism; D005473:Fluoxetine / Q000633:toxicity; D015248:Gemfibrozil / Q000633:toxicity; D008862:Microsomes, Liver / Q000187:drug effects* / Q000201:enzymology; D017686:Oncorhynchus mykiss / Q000502:physiology*; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015027:Zebrafish
chemical_list: D029941:Fish Proteins; D014874:Water Pollutants, Chemical; D005473:Fluoxetine; D002939:Ciprofloxacin; D004917:Erythromycin; D003577:Cytochrome P-450 Enzyme System; D015248:Gemfibrozil