Stereoselective Metabolism of Bupropion by Cytochrome P4502B6 (CYP2B6) and Human Liver Microsomes

Coles, Rebecka; Kharasch, Evan D.

doi:10.1007/s11095-008-9535-1

Cited by 50 publications

(57 citation statements)

References 33 publications

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“…Previous studies have shown that CYP2B6 metabolism of bupropion forms hydroxybupropion (Kirchheiner et al, 2003;Coles and Kharasch, 2008;Kharasch et al, 2008;Benowitz et al, 2013;Ilic et al, 2013). In addition, studies have also suggested that other P450s, such as dmd.aspetjournals.org CYP2C19, CYP2E1, and CYP3A4, might have minor roles in the hydroxybupropion formation, but this still needs to be confirmed (Chen et al, 2010).…”

Section: Discussionmentioning

confidence: 98%

Metabolism of Bupropion by Carbonyl Reductases in Liver and Intestine

et al. 2015

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Bupropion's metabolism and the formation of hydroxybupropion in the liver by cytochrome P450 2B6 (CYP2B6) has been extensively studied; however, the metabolism and formation of erythro/threohydrobupropion in the liver and intestine by carbonyl reductases (CR) has not been well characterized. The purpose of this investigation was to compare the relative contribution of the two metabolism pathways of bupropion (by CYP2B6 and CR) in the subcellular fractions of liver and intestine and to identify the CRs responsible for erythro/threohydrobupropion formation in the liver and the intestine. The results showed that the liver microsome generated the highest amount of hydroxybupropion (Vmax = 131 pmol/min per milligram, Km = 87 μM). In addition, liver microsome and S9 fractions formed similar levels of threohydrobupropion by CR (Vmax = 98-99 pmol/min per milligram and Km = 186-265 μM). Interestingly, the liver has similar capability to form hydroxybupropion (by CYP2B6) and threohydrobupropion (by CR). In contrast, none of the intestinal fractions generate hydroxybupropion, suggesting that the intestine does not have CYP2B6 available for metabolism of bupropion. However, intestinal S9 fraction formed threohydrobupropion to the extent of 25% of the amount of threohydrobupropion formed by liver S9 fraction. Enzyme inhibition and Western blots identified that 11β-dehydrogenase isozyme 1 in the liver microsome fraction is mainly responsible for the formation of threohydrobupropion, and in the intestine AKR7 may be responsible for the same metabolite formation. These quantitative comparisons of bupropion metabolism by CR in the liver and intestine may provide new insight into its efficacy and side effects with respect to these metabolites.

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Section: Discussionmentioning

confidence: 98%

Metabolism of Bupropion by Carbonyl Reductases in Liver and Intestine

et al. 2015

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“…This would suggest perhaps the further investigation of the stereoisomers of other racemic CYP2B6 substrates as stereoselectivity could be an important component of this enzyme. A recent study with individual isomers of bupropion [42], (previously identified as a CYP2B6 substrate and now a widely used probe reaction [5,43,44]) indicated stereoselectivity [K m (R) vs (S), 46µM and 34 µM respectively]. When compared to the racemate with a K m of 107.5µM [45].…”

Section: Discussionmentioning

confidence: 99%

Molecular Characterization of CYP2B6 Substrates

Ekins

Iyer²,

Krasowski³

et al. 2008

CDM

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CYP2B6 has not been as fully characterized at the molecular level as other members of the human cytochrome P450 family. As more widely used in vitro probes for characterizing the involvement of this enzyme in the metabolism of xenobiotics have become available, the number of molecules identified as CYP2B6 substrates has increased. In this study we have analyzed the available kinetic data generated by multiple laboratories with human recombinant expressed CYP2B6 and along with calculated molecular properties derived from the ChemSpider database, we have determined the molecular features that appear to be important for CYP2B6 substrates. In addition we have applied 2D and 3D QSAR methods to generate predictive pharmacophore and 2D models. For 28 molecules with K m data, the molecular weight (mean ± SD) is 253.78±74.03, ACD/logP is 2.68±1.51, LogD pH 5.5 is 1.51±1.43, LogD pH 7.4 is 2.02±1.25, hydrogen bond donor (HBD) count is 0.57 ±0.57, hydrogen bond acceptor (HBA) count is 2.57±1.37, rotatable bonds is 3.50±2.71 and total polar surface area (TPSA) is 27.63±19.42. A second set of 15 molecules without K m data possessed similar mean molecular property values. These properties are comparable to those of a set of 21 molecules used in a previous pharmacophore modeling study (Ekins et al., J Pharmacol Exp Ther 288 (1), 21-29, 1999). Only the LogD and HBD values were statistically significantly different between these different datasets. We have shown that CYP2B6 substrates are generally small hydrophobic molecules that are frequently central nervous system active, which may be important for drug discovery research.

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“…( R,S )-bupropion undergoes stereoselective oxidative metabolism by cytochrome P450 2B6 (CYP2B6) to form (R,R) - and ( S,S )-hydroxybupropion [2]. Additionally, bupropion is stereoselectively reduced by carbonyl reductase(s) to form erythrohydrobupropion and threohydrobupropion [3].…”

Section: Introductionmentioning

confidence: 99%

Development and validation of a high-throughput stereoselective LC–MS/MS assay for bupropion, hydroxybupropion, erythrohydrobupropion, and threohydrobupropion in human plasma

Teitelbaum

Flaker

Kharasch

2016

Journal of Chromatography B

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A stereoselective analytical method was developed and validated for the quantification of bupropion, and principle metabolites hydroxybupropion, erythrohydrobupropion and threohydrobupropion in human plasma. Separation of individual enantiomers (R)-bupropion, (S)-bupropion, (R,R)-hydroxybupropion, (S,S-hydroxybupropion), (1S,2S)-threohydrobupropion, (1R,2R)-threohydrobupropion, (1R,2S)-erythrohydrobupropion, and (1S,2R)-erythrohydrobupropion was achieved utilizing an α1-acid glycoprotein column within a 12-minute run time. Chromatograph separation was significantly influenced by mobile phase pH and variability between columns. Analytes were quantified by positive ion electrospray tandem mass spectrometry following plasma protein precipitation with 20% trichloroacetic acid. Identification of erythrohydrobupropion enantiomer peaks and threohydrobupropion enantiomer peaks was achieved by sodium borohydride reduction of enantiopure (R)- and (S)-bupropion. Initial assay validation and sensitivity determination was on AB Sciex 3200, 4000 QTRAP, and 6500 mass spectrometers. Accuracy and precision were within 15% for each analyte. The assay was fully validated over analyte-specific concentrations using an AB Sciex 3200 mass spectrometer. Intra- and inter-assay precision and accuracy were within 12% for each analyte. The limits of quantification for bupropion (R and S), hydroxybupropion (R,R and S,S), threohydrobupropion (1S,2S and 1R,2R), and erythrohydrobupropion (1R,2S and 1S,2R) were 0.5, 2, 1, and 1 ng/mL, respectively. All analytes were stable following freeze thaw cycles at −80°C and while stored at 4°C in the instrument autosampler. This method was applicable to clinical pharmacokinetic investigations of bupropion in patients. This is the first chromatographic method to resolve erythrohydrobupropion and threohydrobupropion enantiomers, and the first stereoselective LC-MS/MS assay to quantify bupropion, and principle metabolites hydroxybupropion, erythrohydrobupropion, and threohydrobupropion in human plasma.

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Stereoselective Metabolism of Bupropion by Cytochrome P4502B6 (CYP2B6) and Human Liver Microsomes

Abstract: Stereoselective bupropion hydroxylation may have implications for the therapeutic efficacy of bupropion as an antidepressant or smoking cessation therapy, and for the use of bupropion as an in vivo phenotypic probe for CYP2B6 activity.

Cited by 50 publications

References 33 publications

Metabolism of Bupropion by Carbonyl Reductases in Liver and Intestine

Metabolism of Bupropion by Carbonyl Reductases in Liver and Intestine

Molecular Characterization of CYP2B6 Substrates

Development and validation of a high-throughput stereoselective LC–MS/MS assay for bupropion, hydroxybupropion, erythrohydrobupropion, and threohydrobupropion in human plasma

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