Phenotyping Studies to Assess the Effects of Phytopharmaceuticals on In Vivo Activity of Main Human Cytochrome P450 Enzymes

Background: The objective of this study was to examine the inhibitory potential of darifenacin, fesoterodine, oxybutynin, propiverine, solifenacin, tolterodine and trospium chloride on the seven major human cytochrome P450 enzymes (CYP) by using a standardized and validated seven-in-one cytochrome P450 cocktail inhibition assay. Methods: An in vitro cocktail of seven highly selective probe substrates was incubated with human liver microsomes and varying concentrations of the seven test compounds. The major metabolites of the probe substrates were simultaneously analysed using a validated liquid chromatography tandem mass spectrometry (LC-MS/MS) method. Enzyme kinetics were estimated by determining IC50 and Ki values via nonlinear regression. Obtained Ki values were used for predictions of potential clinical impact of the inhibition using a static mechanistic prediction model. Results: In this study, 49 IC50 experiments were conducted. In six cases, IC50 values lower than the calculated threshold for drug–drug interactions (DDIs) in the gut wall were observed. In these cases, no increase in inhibition was determined after a 30 min preincubation. Considering a typical dosing regimen and applying the obtained Ki values of 0.72 µM (darifenacin, 15 mg daily) and 7.2 µM [propiverine, 30 mg daily, immediate release (IR)] for the inhibition of CYP2D6 yielded a predicted 1.9-fold and 1.4-fold increase in the area under the curve (AUC) of debrisoquine (CYP2D6 substrate), respectively. Due to the inhibition of the particular intestinal CYP3A4, the obtained Ki values of 14 µM of propiverine (30 mg daily, IR) resulted in a predicted doubling of the AUC for midazolam (CYP3A4 substrate). Conclusions: In vitro/ in vivo extrapolation based on pharmacokinetic data and the conducted screening experiments yielded similar effects of darifenacin on CYP2D6 and propiverine on CYP3A4 as obtained in separately conducted in vivo DDI studies. As a novel finding, propiverine was identified to potentially inhibit CYP2D6 at clinically occurring concentrations.

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Inhibition of human cytochrome P450 enzymes by 1,4-dihydropyridine calcium antagonists: prediction of in vivo drug-drug interactions

European Journal of Clinical Pharmacology ◽

10.1007/s002280050706 ◽

2000 ◽

Vol 55 (11-12) ◽

pp. 843-852 ◽

Cited By ~ 98

Author(s):

M. Katoh ◽

M. Nakajima ◽

N. Shimada ◽

H. Yamazaki ◽

T. Yokoi

Keyword(s):

Cytochrome P450 ◽

Drug Interactions ◽

Calcium Antagonists ◽

Cytochrome P450 Enzymes ◽

Human Cytochrome

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Carbon-Carbon Bond Cleavage Catalyzed by Human Cytochrome P450 Enzymes: a-Ketol as the Key Intermediate Metabolite in Sequential Metabolism of Olanexidine

Drug Metabolism Letters ◽

10.2174/1872312813666191125095818 ◽

2019 ◽

Vol 13 ◽

Author(s):

Yiding Hu ◽

Yi Xiao ◽

Zhesui Rao ◽

Vasant Kumar ◽

Hanlan Liu ◽

...

Keyword(s):

Cytochrome P450 ◽

Bond Cleavage ◽

Liver Microsomes ◽

Side Chain ◽

Cytochrome P450 Enzymes ◽

Acid Metabolite ◽

Carbon Bond ◽

Carbon Carbon Bond ◽

Human Cytochrome

Background: Carbon-carbon bond cleavage of a saturated aliphatic moiety is rarely seen in xenobiotic metabolism. Olanexidine (Olanedine®), containing an n-octyl (C8) side chain, was mainly metabolized to various shortened side chain (C4 to C6) acid-containing metabolites in vivo in preclinical species. In liver microsomes and S9, the major metabolites of olanexidine were from multi-oxidation on its n-octyl (C8) side chain. However, the carbon-carbon bond cleavage mechanism of n-octyl (C8) side chain, and enzyme(s) responsible for its metabolism in human remained unknown. Methods: A pair of regioisomers of -ketol-containing C8 side chain olanexidine analogs (3,2-ketol olanexidine and 2,3-ketol olanexidine) were synthesized, followed by incubation in human liver microsomes, recombinant human cytochrome P450 enzymes or human hepatocytes, and subsequent metabolite identification using LC/UV/MS. Results: Multiple shortened side chain (C4 to C6) metabolites were identified, including C4, C5 and C6-acid and C6-hydroxyl metabolites. Among 19 cytochrome P450 enzymes tested, CYP2D6, CYP3A4 and CYP3A5 were identified to catalyze carbon-carbon bond cleavage. Conclusions: 3,2-ketol olanexidine and 2,3-ketol olanexidine were confirmed as the key intermediates in carbon-carbon bond cleavage. Its mechanism is proposed that a nucleophilic addition of iron-peroxo species, generated by CYP2D6 and CYP3A4/5, to the carbonyl group caused the carbon-carbon bond cleavage between the adjacent hydroxyl and ketone groups. As results, 2,3-ketol olanexidine formed a C6 side chain acid metabolite. While, 3,2-ketol olanexidine formed a C6 side chain aldehyde intermediate, which was either oxidized to a C6 side chain acid metabolite or reduced to a C6 side chain hydroxyl metabolite.

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IN VIVO INDUCTION OF HUMAN CYTOCHROME P450 ENZYMES EXPRESSED IN CHIMERIC MICE WITH HUMANIZED LIVER

Drug Metabolism and Disposition ◽

10.1124/dmd.104.002600 ◽

2005 ◽

Vol 33 (6) ◽

pp. 754-763 ◽

Cited By ~ 44

Author(s):

Miki Katoh ◽

Tomohito Matsui ◽

Miki Nakajima ◽

Chise Tateno ◽

Yoshinori Soeno ◽

...

Keyword(s):

Cytochrome P450 ◽

Chimeric Mice ◽

Cytochrome P450 Enzymes ◽

Human Cytochrome ◽

In Vivo Induction

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Metabolism and Interactions of Chloroquine and Hydroxychloroquine with Human Cytochrome P450 Enzymes and Drug Transporters

Current Drug Metabolism ◽

10.2174/1389200221999201208211537 ◽

2020 ◽

Vol 21 (14) ◽

pp. 1127-1135

Author(s):

Slobodan Rendic ◽

Frederick Peter Guengerich

Keyword(s):

Cytochrome P450 ◽

Inflammatory Diseases ◽

Drug Transporters ◽

Transport Systems ◽

Cytochrome P450 Enzymes ◽

Human Cytochrome ◽

Metabolic Properties ◽

P450 2D6

Background:: In clinical practice, chloroquine and hydroxychloroquine are often co-administered with other drugs in the treatment of malaria, chronic inflammatory diseases, and COVID-19. Therefore, their metabolic properties and the effects on the activity of cytochrome P450 (P450, CYP) enzymes and drug transporters should be considered when developing the most efficient treatments for patients. Methods:: Scientific literature on the interactions of chloroquine and hydroxychloroquine with human P450 enzymes and drug transporters, was searched using PUBMED.Gov (https://pubmed.ncbi.nlm.nih.gov/) and the ADME database (https://life-science.kyushu.fujitsu.com/admedb/). Results:: Chloroquine and hydroxychloroquine are metabolized by P450 1A2, 2C8, 2C19, 2D6, and 3A4/5 in vitro and by P450s 2C8 and 3A4/5 in vivo by N-deethylation. Chloroquine effectively inhibited P450 2D6 in vitro; however, in vivo inhibition was not apparent except in individuals with limited P450 2D6 activity. Chloroquine is both an inhibitor and inducer of the transporter MRP1 and is also a substrate of the Mate and MRP1 transport systems. Hydroxychloroquine also inhibited P450 2D6 and the transporter OATP1A2. Conclusions:: Chloroquine caused a statistically significant decrease in P450 2D6 activity in vitro and in vivo, also inhibiting its own metabolism by the enzyme. The inhibition indicates a potential for clinical drug-drug interactions when taken with other drugs that are predominant substrates of the P450 2D6. When chloroquine and hydroxychloroquine are used clinically with other drugs, substrates of P450 2D6 enzyme, attention should be given to substrate-specific metabolism by P450 2D6 alleles present in individuals taking the drugs.

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