A fully automated assay to determine the enzymology of drug oxidation by the major human hepatic cytochrome P450s (CYPs; CYP1A2, -2C9, -2C19, -2D6, and -3A4) coexpressed functionally in Escherichia coli with human NADPH-P450 reductase has been developed and validated. Ten prototypic substrates were chosen for which clearance was primarily CYP-dependent, and the activities of these five major CY...

Because codeine (COD) is eliminated primarily via glucuronidation, factors that alter COD glucuronide formation potentially affect the proportion of the dose converted to the pharmacologically active metabolite morphine. Thus, in vitro-in vivo extrapolation approaches were used to identify potential drug-drug interactions arising from inhibition of COD glucuronidation in humans. Initial studies...

A higher throughput method of screening for the inhibition of recombinant CYP2D6 using a microtiter plate (MTP) assay was evaluated using 62 new chemical entities and compared to data from the dextromethorphan O-demethylase assay in human liver microsomes (HLM). The IC50 values for the two assays closely matched for 53 compounds (85%). Six of the variant nine compounds had higher IC50 values wi...

Cytochrome P450 (P450) enzymes are major catalysts involved in the metabolism of xenobiotics and endogenous substrates such as testosterone (TST). Major TST metabolites formed by human liver microsomes include 6beta-hydroxytestosterone (6beta-OHTST), 2beta-hydroxytestosterone (2beta-OHTST), and 15beta-hydroxytestosterone (15beta-OHTST). A screen of 16 cDNA-expressed human P450 isoforms demonstr...

Esculetin (6,7-dihydroxycoumarin, ET) and 4-methylesculetin (6,7dihydroxy-4-methylcoumarin, 4-ME) are typical coumarin derivatives that are attracting considerable attention because of their wide spectrum of biologic activities, but their metabolism remains unknown. This study aimed to elucidate the in vitro UDPglucuronosyltransferase (UGT) metabolism characteristics of ET and 4-ME. 7-O-monoglu...

Problem 1: If you forget to set the variable type for the string variables by adding a dollar sign after those variables on the INPUT statement, they don’t read in, and you get “.” for missing values. If you neglect to make the strings longer than the default 8 characters, two pairs of sessions appear the same because their first 8 letters are the same. The histogram of score shows that people ...