Gina M. Giancarlo

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Objectives: To determine the relative contribution of cytochromes P 450 (CYP) 2C9 and 2C19 to the formation of 5-(-4-hydroxyphenyl)-5-phenylhydantion (HPPH) from phenytoin (PPH). Design: Hydroxylation of PPH to form HPPH was studied in vitro using human liver microsomes and microsomes from cDNA-transfected human lymphoblastoid cells. Results: Formation of(More)
Transformation of escitalopram (S-CT), the pharmacologically active S-enantiometer of citalopram, to S-desmethyl-CT (S-DCT), and of S-DCT to S-didesmethyl-CT (S-DDCT), was studied in human liver microsomes and in expressed cytochromes (CYPs). Biotransformation of the R-enantiomer (R-CT) was studied in parallel. S-CT was transformed to S-DCT by CYP2C19 (K(m)(More)
Zafirlukast is a cysteinyl leukotriene antagonist used to treat allergic and exercise-induced asthma. This in vitro study used human liver microsomes to evaluate the inhibitory activity of zafirlukast versus six human cytochrome P450 (CYP) isoforms. Zafirlukast (0-250 microM) was co-incubated with fixed concentrations of index substrates. Zafirlukast(More)
The capacity of three clinically available nonnucleoside reverse transcriptase inhibitors (NNRTIs) to inhibit the activity of human cytochromes P450 (CYPs) was studied in vitro using human liver microsomes. Delavirdine, nevirapine, and efavirenz produced negligible inhibition of phenacetin O-deethylation (CYP1A2) or dextromethorphan O-demethylation(More)
Biotransformation of gepirone to 1-(2-pyrimidinyl)-piperazine (1-PP) and 3'-OH-gepirone, as well as two other hydroxylated metabolites, was studied in vitro using a human liver microsomal preparation and heterologously expressed human CYP3A4 and CYP2D6. The focus was on a low range of gepirone concentrations (1000 nM and below). Liver microsomes formed 1-PP(More)
A method has been developed to quantify ritonavir concentrations in human plasma and in mouse serum, liver, and brain using high-performance liquid chromatography. Extraction recoveries for ritonavir and its internal standard averaged greater than 95%. Within-day variability, expressed as a coefficient of variation, averaged 6% over the concentration range(More)
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