In Vitro Enzyme Kinetics Applied to Drug-Metabolizing Enzymes

2001 ◽  
pp. 64-85 ◽  
Keyword(s):  
Enzyme Kinetics ◽  
Drug Metabolizing Enzymes ◽  
Metabolizing Enzymes

scholarly journals In Vitro Evaluation of the Drug Interaction Potential of Doravirine

2019 ◽  
Vol 63 (4) ◽  
Author(s):  
Kelly Bleasby ◽  
Kerry L. Fillgrove ◽  
Robert Houle ◽  
Bing Lu ◽  
Jairam Palamanda ◽  
...  
Keyword(s):  
Drug Interactions ◽  
Organic Anion ◽  
Organic Anion Transporter ◽  
Reversible Inhibitor ◽  
Drug Metabolizing Enzymes ◽  
Cancer Resistance ◽  
Metabolizing Enzymes ◽  
Anion Transporter ◽  
Major Drug

ABSTRACT Doravirine is a novel nonnucleoside reverse transcriptase inhibitor for the treatment of human immunodeficiency virus type 1 infection. In vitro studies were conducted to assess the potential for drug interactions with doravirine via major drug-metabolizing enzymes and transporters. Kinetic studies confirmed that cytochrome P450 3A (CYP3A) plays a major role in the metabolism of doravirine, with ∼20-fold-higher catalytic efficiency for CYP3A4 versus CYP3A5. Doravirine was not a substrate of breast cancer resistance protein (BCRP) and likely not a substrate of organic anion transporting polypeptide 1B1 (OATP1B1) or OATP1B3. Doravirine was not a reversible inhibitor of major CYP enzymes (CYP1A2, -2B6, -2C8, -2C9, -2C19, -2D6, and -3A4) or of UGT1A1, nor was it a time-dependent inhibitor of CYP3A4. No induction of CYP1A2 or -2B6 was observed in cultured human hepatocytes; small increases in CYP3A4 mRNA (≤20%) were reported at doravirine concentrations of ≥10 μM but with no corresponding increase in enzyme activity. In vitro transport studies indicated a low potential for interactions with substrates of BCRP, P-glycoprotein, OATP1B1 and OATP1B3, the bile salt extrusion pump (BSEP), organic anion transporter 1 (OAT1) and OAT3, organic cation transporter 2 (OCT2), and multidrug and toxin extrusion 1 (MATE1) and MATE2K proteins. In summary, these in vitro findings indicate that CYP3A4 and CYP3A5 mediate the metabolism of doravirine, although with different catalytic efficiencies. Clinical trials reported elsewhere confirm that doravirine is subject to drug-drug interactions (DDIs) via CYP3A inhibitors and inducers, but they support the notion that DDIs (either direction) are unlikely via other major drug-metabolizing enzymes and transporters.

Effects of chronic ethanol administration in the rat: relative dependency on dietary lipids. II. Paradoxical role of linoleate in the induction of hepatic drug-metabolizing enzymes in vitro

1977 ◽  
Vol 55 (1) ◽  
pp. 34-41 ◽  
Author(s):  
Jean-Gil Joly ◽  
Claude Hétu
Keyword(s):  
Dietary Lipid ◽  
Dietary Lipids ◽  
Chronic Ethanol ◽  
Ethanol Administration ◽  
Drug Metabolizing Enzymes ◽  
Metabolizing Enzymes ◽  
Drug Biotransformation ◽  
Chronic Ethanol Administration ◽  
Cytochrome P 450

The effect of chronic ethanol administration on the hepatic microsomal cytochrome P-450 content and activities of NADPH – cytochrome P-450 reductase (EC 1.6.2.4), benzphetamine demethylase, aniline hydroxylase (EC 1.14.14.1), and of the microsomal ethanol-oxidizing system were studied in various dietary models. When ethanol was given with linoleate as the only source of dietary lipid, the ethanol induction of these parameters was greater with diets containing 2 or 5% of total calories as linoleate than with diets containing 10% of total calories as linoleate. By contrast, when ethanol was given with high fat (35% of total calories) diets, the ethanol induction of these same parameters was slightly greater when linoleate provided 10% of total calories than when it provided 3% of calories. The apparent effect of dietary linoleate on the induction, by ethanol, of microsomal drug-metabolizing enzymes is markedly different when linoleate is given as the only source of dietary lipid as opposed to when it is given with other dietary lipids. Thus, conclusions on the effect of ethanol on hepatic microsomal drug-biotransformation enzymes, drawn from studies with dietary models in which linoleate provides the only source of dietary lipid, cannot be extended to dietary models of more complex lipid composition. When given as the only source of lipid, 2% of total calories in linoleate appears optimal for basal activity and inductibility, by ethanol, of mixed-function oxidases.

Species Differences in the Response of Liver Drug-Metabolizing Enzymes to (S)-4-O-Tolylsulfanyl-2-(4-trifluormethyl-phenoxy)-butyric Acid (EMD 392949) in Vivo and in Vitro

2008 ◽  
Vol 36 (4) ◽  
pp. 702-714 ◽  
Author(s):  
Lysiane Richert ◽  
Gregor Tuschl ◽  
Catherine Viollon-Abadie ◽  
Nadège Blanchard ◽  
Alexandre Bonet ◽  
...  
Keyword(s):  
Butyric Acid ◽  
Species Differences ◽  
Drug Metabolizing Enzymes ◽  
Metabolizing Enzymes
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