Assessment of multiple cytochrome P450 activities in metabolically inactivated human liver microsomes and roles of P450 2C isoforms in reaction phenotyping studies.

The fraction of substrate metabolized (f ) can be used to estimate drug interactions and can be determined by comparison of the intrinsic clearances (CL ) of victim drugs obtained from inhibited and uninhibited hepatic enzymes Commercially available human liver microsomes were recently developed in which one cytochrome P450 (P450) isoform is selectively inactivated. These inactivated liver microsomes were used to evaluate the roles of P450 2C isoforms in the depletion and oxidation of probe substrates. Determination of CL with sets of control and P450 2C9-inactivated liver microsomes yielded f values of 0.

Evaluation of 23 lots of commercially available cryopreserved hepatocytes for induction assays of human cytochromes P450.

Due to the importance of in vitro cytochrome P450 (P450) induction assay to assess the possible drug-drug interaction events, the recent US Food and Drug Administration draft guidance and European Medicines Agency guideline recommend to assess P450 induction using fresh or cryopreserved hepatocytes at mRNA level and/or enzyme activity level. Although cryopreserved hepatocytes are commercially available for P450 induction assays, feasibility and practicability of these hepatocytes have not been fully investigated. In this study, a total of 23 lots of human cryopreserved hepatocytes were treated with three typical inducers (omeprazole, phenobarbital, and rifampicin), and induction of CYP1A2, CYP2B6, and CYP3A4 enzyme activity was measured.

Thalidomide increases human hepatic cytochrome P450 3A enzymes by direct activation of the pregnane X receptor.

Heterotropic cooperativity of human cytochrome P450 (P450) 3A4/3A5 by the teratogen thalidomide was recently demonstrated by H. Yamazaki et al. ( ( 2013 ) Chem.

Data on Wistar Hannover rats from a general toxicity study.

The aim of this study was to collect data on chronological changes in clinical laboratory tests, pathological examinations, and hepatic drug-metabolizing enzymes from Wistar Hannover rats at 8, 10, 19, and 32 weeks of age. The serum triglyceride concentration and the serum LDL cholesterol level were higher in males than in females at all ages. In contrast, serum total protein and creatinine concentrations and cholinesterase activity were lower in males than in females.

Identification of human cytochrome P450 isoforms and esterases involved in the metabolism of mirabegron, a potent and selective β3-adrenoceptor agonist.

1. Human cytochrome P450 (CYP) enzymes and esterases involved in the metabolism of mirabegron, a potent and selective human β(3)-adrenoceptor agonist intended for the treatment of overactive bladder, were identified in in vitro studies. 2.

Identification of enzymes responsible for the N-oxidation of darexaban glucuronide, the pharmacologically active metabolite of darexaban, and the glucuronidation of darexaban N-oxides in human liver microsomes.

Darexaban maleate is a novel oral direct factor Xa inhibitor. Darexaban glucuronide (YM-222714) was the major component in plasma after oral administration of darexaban to humans and is the pharmacologically active metabolite. Additionally, YM-222714 N-oxides were detected as minor metabolites in human plasma and urine.

Identification of UDP-glucuronosyltransferases responsible for the glucuronidation of darexaban, an oral factor Xa inhibitor, in human liver and intestine.

Darexaban maleate is a novel oral direct factor Xa inhibitor, which is under development for the prevention of venous thromboembolism. Darexaban glucuronide was the major component in plasma after oral administration of darexaban to humans and is the pharmacologically active metabolite. In this study, we identified UDP-glucuronosyltransferases (UGTs) responsible for darexaban glucuronidation in human liver microsomes (HLM) and human intestinal microsomes (HIM).

Gender-related difference in the toxicity of 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole in rats: relationship to the plasma concentration, in vitro hepatic metabolism, and effects on hepatic metabolizing enzyme activity.

Previously, we showed that the toxic susceptibility of male rats to an ultraviolet absorber, 2-(2'-hydroxy- 3',5'-di-tert-butylphenyl)benzotriazole (HDBB), was nearly 25 times higher than that of females. The present study aimed to clarify the mechanism of gender-related differences in HDBB toxicity. Male and female rats were given HDBB by gavage at 0.

Evaluation of drug-drug interaction potential of beraprost sodium mediated by P450 in vitro.

Beraprost sodium (BPS), a chemically stable and orally active prostacyclin analogue used for the treatment of chronic occlusive disease and primary pulmonary hypertension, was investigated in terms of its drug-drug interaction mediated by cytochrome P450. In a metabolic enzyme characterization study using P450-expressing insect cell microsomes, beraprost (BP) was slightly metabolized in the presence of CYP2C8, but not metabolized by the other P450 isoforms (CYP1A2, [corrected] CYP2A6, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4, and CYP4A11) at a concentration of 20 microM. These results suggest that none of the P450 isoforms is a major metabolic enzyme of BP.