Decreased susceptibility of the cytochrome P450 2B6 variant K262R to inhibition by several clinically important drugs

Jyothi C. Talakad, Santosh Kumar, James R. Halpert

Research output: Contribution to journalArticle

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Abstract

Cytochrome P450 (P450) 2B6 metabolizes a number of clinically relevant drugs and is one of the most highly polymorphic human P450 enzymes, with the Lys 262→Arg substitution being especially common in several genetic variants. Therefore, K262R (2B6*4) was created in the CYP2B6dH background (N-terminal-modified and C-terminal His-tagged) and expressed in Escherichia coli. The recombinant CYP2B6dH and K262R were purified and studied to investigate the effect of the Lys 262→Arg substitution with six of the most potent drug inhibitors of CYP2B6, namely, Clopidogrel, clotrimazole, itraconazole, raloxifene, sertraline, and ticlopidine. K262R showed a >3-fold increase in the K i values with Clopidogrel, itraconazole, and raloxifene and 6-fold increase in K i with sertraline compared with CYP2B6dH. Likewise, K262R showed 2-, 4-, and > 20-fold higher K s values than CYP2B6dH with Clopidogrel, sertraline, and itraconazole, respectively. In contrast, when tested with several known type II inhibitors of CYP2B enzymes, K262R showed a 10-fold lower IC 50 with 4-(phenyl)pyridine and 2-fold lower IC 50 with 4-(4-nitrobenzyl)pyridine or 1 -(4-phenyl)benzylimidazole than CYP2B6dH. Subsequent analysis predicted possible in vivo drug-drug interactions between the CYP2B6 substrate efavirenz and drug inhibitors Clopidogrel, clotrimazole, itraconazole, sertraline, and ticlopidine. Furthermore, Q172H/K262R (2B6*6), which is the most common genetic variant of CYP2B6 harboring K262R, was created in CYP2B6dH, expressed, purified, and characterized for inhibition. Q172H/K262R showed a > 6-fold increase in K i with sertraline and Clopidogrel compared with CYP2B6dH. The results suggest that individuals, especially homozygotes, with the 2B6*4 or 2B6*6 allele might be less susceptible to drug interactions resulting from P450 inhibition.

Original languageEnglish (US)
Pages (from-to)644-650
Number of pages7
JournalDrug Metabolism and Disposition
Volume37
Issue number3
DOIs
StatePublished - Mar 1 2009
Externally publishedYes

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clopidogrel
Sertraline
Itraconazole
Clotrimazole
Ticlopidine
Pharmaceutical Preparations
efavirenz
Drug Interactions
Cytochrome P-450 Enzyme System
Homozygote
Enzyme Inhibitors
Alleles
Cytochrome P-450 CYP2B6
Escherichia coli

All Science Journal Classification (ASJC) codes

  • Pharmacology
  • Pharmaceutical Science

Cite this

Decreased susceptibility of the cytochrome P450 2B6 variant K262R to inhibition by several clinically important drugs. / Talakad, Jyothi C.; Kumar, Santosh; Halpert, James R.

In: Drug Metabolism and Disposition, Vol. 37, No. 3, 01.03.2009, p. 644-650.

Research output: Contribution to journalArticle

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abstract = "Cytochrome P450 (P450) 2B6 metabolizes a number of clinically relevant drugs and is one of the most highly polymorphic human P450 enzymes, with the Lys 262→Arg substitution being especially common in several genetic variants. Therefore, K262R (2B6*4) was created in the CYP2B6dH background (N-terminal-modified and C-terminal His-tagged) and expressed in Escherichia coli. The recombinant CYP2B6dH and K262R were purified and studied to investigate the effect of the Lys 262→Arg substitution with six of the most potent drug inhibitors of CYP2B6, namely, Clopidogrel, clotrimazole, itraconazole, raloxifene, sertraline, and ticlopidine. K262R showed a >3-fold increase in the K i values with Clopidogrel, itraconazole, and raloxifene and 6-fold increase in K i with sertraline compared with CYP2B6dH. Likewise, K262R showed 2-, 4-, and > 20-fold higher K s values than CYP2B6dH with Clopidogrel, sertraline, and itraconazole, respectively. In contrast, when tested with several known type II inhibitors of CYP2B enzymes, K262R showed a 10-fold lower IC 50 with 4-(phenyl)pyridine and 2-fold lower IC 50 with 4-(4-nitrobenzyl)pyridine or 1 -(4-phenyl)benzylimidazole than CYP2B6dH. Subsequent analysis predicted possible in vivo drug-drug interactions between the CYP2B6 substrate efavirenz and drug inhibitors Clopidogrel, clotrimazole, itraconazole, sertraline, and ticlopidine. Furthermore, Q172H/K262R (2B6*6), which is the most common genetic variant of CYP2B6 harboring K262R, was created in CYP2B6dH, expressed, purified, and characterized for inhibition. Q172H/K262R showed a > 6-fold increase in K i with sertraline and Clopidogrel compared with CYP2B6dH. The results suggest that individuals, especially homozygotes, with the 2B6*4 or 2B6*6 allele might be less susceptible to drug interactions resulting from P450 inhibition.",
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