Dual Effects of Ketoconazole cis-Enantiomers on CYP3A4 in Human Hepatocytes and HepG2 Cells

Abstract

Antifungal drug ketoconazole causes severe drug-drug interactions by influencing gene expression and catalytic activity of major drug-metabolizing enzyme cytochrome P450 CYP3A4. Ketoconazole is administered in the form of racemic mixture of two cis-enantiomers, i.e. (+)-ketoconazole and (−)-ketoconazole. Many enantiopure drugs were introduced to human pharmacotherapy in last two decades. In the current paper, we have examined the effects of ketoconazole cis-enantiomers on the expression of CYP3A4 in human hepatocytes and HepG2 cells and on catalytic activity of CYP3A4 in human liver microsomes. We show that both ketoconazole enantiomers induce CYP3A4 mRNA and protein in human hepatocytes and HepG2 cells. Gene reporter assays revealed partial agonist activity of ketoconazole enantiomers towards pregnane X receptor PXR. Catalytic activity of CYP3A4/5 towards two prototypic substrates of CYP3A enzymes, testosterone and midazolam, was determined in presence of both (+)-ketoconazole and (−)-ketoconazole in human liver microsomes. Overall, both ketoconazole cis-enantiomers induced CYP3A4 in human cells and inhibited CYP3A4 in human liver microsomes. While interaction of ketoconazole with PXR and induction of CYP3A4 did not display enantiospecific pattern, inhibition of CYP3A4 catalytic activity by ketoconazole differed for ketoconazole cis-enantiomers ((+)-ketoconazole IC50 1.69 µM, Ki 0.92 µM for testosterone, IC50 1.46 µM, Ki 2.52 µM for midazolam; (−)-ketoconazole IC50 0.90 µM, Ki 0.17 µM for testosterone, IC50 1.04 µM, Ki 1.51 µM for midazolam).

Exploring the Carbamazepine Interaction with Human Pregnane X Receptor and Effect on ABCC2 Using in Vitro and in Silico Approach

“…The effect of ketoconazole observed in our study is in line with other studies where they have used other agonists (26,66). For instance, Novotna et al reported when ketoconazole was given alone it activated PXR, whereas when given in combination with rifampicin, it dose dependently inhibited PXR (68).…”

Changes in cytochrome P450 gene expression and enzyme activity induced by xenobiotics in rabbits in vivo and in vitro

“…According to the qRT-PCR results, ketoconazole treatment increased rabbit hepatocyte CYP1A1 and CYP3A6 gene expression of hepatocytes in vitro, but the gene expression level of CYP1A1 remained unchanged in vivo after 3 d of ketoconazole treatment. Ketoconazole upregulated the gene expression of CYP3A6 both in vitro and in vivo, in line with previous findings that ketoconazole increased the gene expression of CYP3A4 in human cell lines and human primary hepatocytes (Novotna et al, 2014). This is the first proof of the inducer effect of ketoconazole on CYP1A1 enzyme activity in vivo in rabbits.…”

Drug interaction at hERG channel: In vitro assessment of the electrophysiological consequences of drug combinations and comparison against theoretical models

“…Its role in the drug-triggered arrhythmia occurrence is more likely an effect of the CYP3A4/5 inhibition, and increase of the victim exposure (e.g., terfenadine case). Considering only the standard probe used as the victim compound (midazolam) the values range from 0.0052 up to 2.28 μM, which is hundreds of folds lower as compared against the IC 50 value for the hERG inhibition (value reported in the current study is 0.74 μM) (Li, Andersson, Ahlström, & Weidolf, 2004;Novotná et al, 2014). LOR and DES are not listed in the CredibleMeds classifications.…”