In Vitro Assessment Of CYP Inhibition, Time-dependent Inhibition In Human Liver Mcrosomes And CYP Induction In Human Hepatocyte

As a significant role in endo-and exo-genous compound metabolism, the Cytochrome P450takes part in metabolic activation of variant drugs, precarcinogens, prepoisons and deletion of variant drugs.CYP450inhibition was evaluated in vitro through five major cytochrome P450(CYP) enzymes fora-Naphthoflavon, Sulfaphenazole, Omeperazole, Quinidine, and Ketoconazole in screen modes. The assays were conducted in pooled human liver microsomes (HLM) after incubation of the test compounds in the CYP enzymes added into the another incubation systems containing known substrates and the cofactor. CYP enzyme activities were determined based on metabolite production quantified by LC/MS/MS. The IC50ofa-Naphthoflavon, Sulfaphenazole, Omeperazole, Quinidine, and Ketoconazole in HLM was0.0061μM on CYP1A2,0.4025μM on CYP2C9,0.0363μM on CYP2D6,0.0122μM on CYP3A4and4.7350μM on CYP2C19, respectively. The results generated were comparable with those reported in the literature.Time-dependent inhibition (TDI) was evaluated in vitro through five major cytochrome P450(CYP) enzymes for furafylline, tienilic acid, paroxetine, mifepristone, and ticlopidine in both screen and kinetic characterization modes. The assays were conducted either in pooled hμMan liver microsomes (HLM) or in recombinant hμMan CYPs (rhCYP) after pre-incubation of the test compounds in the CYP enzymes in the presence or absence of NADPH (cofactor) followed by10×dilution into the secondary incubation systems containing known substrates and the cofactor. CYP enzyme activities were determined based on metabolite production quantified by LC/MS/MS. A single time point (30-min) pre-incubation of furafylline, tienilic acid, paroxetine, mifepristone, and ticlopidine in HLM or rhCYP resulted in inhibition on CYP enzymes by90%on CYP1A2,80%on CYP2C9,60%on CYP2D6,54%on CYP3A4and54%on CYP2C19, respectively. The KI and kinact values were also determined for the test compounds in HLM or rhCYP after multiple pre-incubation time points at multiple concentrations under the current assay conditions. The results generated were comparable with those reported in the literature.CYP450induction was evaluated in vitro through two major cytochrome P450(CYP) enzymes for3-MC and dexamethasone in screen modes. The assays were conducted in rat hepatocyte after incubation of the test compounds in the rat hepatocyte. CYP enzyme activities was determined based on metabolite production quantified by LC/MS/MS. Incubation of3-MC and dexamethasone in rat hepatocyte resulted in induction on CYP enzymes by more than200%on CYP1A2and CYP3A4respective.