Importance of Cyp2d3 in Polymorphism of Diazepam P-Hydroxylation in Rats

Sakai, Noriaki; Saito, Katsuharu; Kim, Hyungsub; Kazusaka, Akio; Ishizuka, Mayumi; Funae, Yoshihiko; Fujita, Shoichi

doi:10.1124/dmd.105.004242

Cited by 10 publications

(10 citation statements)

References 17 publications

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“…WistarImamichi rats have higher concentrations of acetohexamide than Sprague-Dawley rats owing to the reduced activity of carbonyl reductase in liver microsomes (Imamura and Shimada, 2005). Metabolic clearances of diazepam differ among Sprague-Dawley rats, Brown Norway rats, and Wistar rats, in which differences in both the rate of elimination and the metabolic pathways of diazepam are due to polymorphic expression of the enzymes involved in diazepam metabolism (Saito et al, 2004;Sakai et al, 2005). These results are useful for predicting the variability in human pharmacokinetics if the mechanisms of such differences are completely understood.…”

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confidence: 99%

Marked Strain Differences in the Pharmacokinetics of an α4β1 Integrin Antagonist, 4-[1-[3-Chloro-4-[N-(2-methylphenyl)-ureido]phenylacetyl]-(4 S)-fluoro-(2 S)-pyrrolidine-2-yl]-methoxybenzoic Acid (D01-4582), in Sprague-Dawley Rats Are Associated with Albumin Genetic Polymorphism

Ito¹,

Takahashi²,

Sudo³

et al. 2007

The Journal of Pharmacology and Experimental Therapeutics

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Strain differences in pharmacokinetics of an ␣ 4 ␤ 1 integrin antagonist, 4-[1-[3-chloro-4-[N-(2-methylphenyl)-ureido]phenylacetyl]-(4S)-fluoro-(2S)-pyrrolidine-2-yl]methoxybenzoic acid (D01-4582), in Sprague-Dawley rat strains (SD rat and CD rat) and their mechanism were investigated. Total plasma clearances of D01-4582 were 31.5 and 5.23 ml/min/kg in SD and CD rats, respectively. From in vivo studies, hepatic uptake process was thought to be involved in the strain differences. Differences in the uptake of D01-4582 by isolated hepatocytes prepared from the both strains were not observed when hepatocytes were incubated with simple buffer, but marked differences were observed when hepatocytes were incubated with plasma. When the dissociation constants (K d ) for the plasma protein binding of D01-4582 were examined in six rat strains, each strain was classified into two groups: a high-K d group, which included SD rats, Brown Norway rats, and Wistar rats; and a low-K d group, which included CD rats, Lewis rats, and Eisai hyperbilirubinemic rats. Since all rat strains in the low-K d group showed higher area under the concentration-time curve for D01-4582 than rats in the high-K d group, it was considered that the strain differences in the pharmacokinetics of D01-4582 were due to differences in the binding affinity. Purified albumin also showed strain differences in K d . The cDNA sequence of the albumin was analyzed, and 11 substitutions were observed. V238L and T293I were found only in the high-K d group, suggesting that these amino acid changes reduced the binding affinity of albumin for D01-4582. In conclusion, the strain differences in D01-4582 pharmacokinetics were suggested to be caused by an alteration in K d , associated with albumin genetic polymorphism.In the process of drug discovery and development, the properties of drug candidates are assessed and screened for their pharmacological, toxicological, and pharmacokinetic aspects. One important issue in the pharmacokinetic evaluation is the prediction of interindividual variabilities in plasma concentrations in humans. For this purpose, the metabolic pathway, elimination route, and their relevant proteins are characterized, because metabolism and membrane transport, in most cases, govern the plasma concentration profiles of a drug. Once the relevant protein, e.g., CYP3A4 or OATP1B1, has been identified, information on the frequency of the variants with reduced activity helps us to estimate the risk of the occurrence of interindividual variabilities (Sadee, 1998;Pirmohamed and Park, 2001;Tribut et al., 2002;Evans and McLeod, 2003). Animal models, such as knockout mice and naturally occurring deficient animals, are useful for demonstrating the importance of the protein in vivo. If pharmacokinetics differ in model animals compared with that in normal animals, the protein of interest would play an important role in vivo. In other words, pharmacokinetic differences in model animals would imply the possibility that interindiArticle, publication date, and...

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confidence: 99%

Marked Strain Differences in the Pharmacokinetics of an α4β1 Integrin Antagonist, 4-[1-[3-Chloro-4-[N-(2-methylphenyl)-ureido]phenylacetyl]-(4 S)-fluoro-(2 S)-pyrrolidine-2-yl]-methoxybenzoic Acid (D01-4582), in Sprague-Dawley Rats Are Associated with Albumin Genetic Polymorphism

Ito¹,

Takahashi²,

Sudo³

et al. 2007

The Journal of Pharmacology and Experimental Therapeutics

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“…CYP2D4 protein in liver microsomes (Sakai et al, 2005). These data suggest that DA rats have a unique expression pattern in the CYP2D subfamily.…”

Section: Tablementioning

confidence: 62%

“…The considerable differences in the plasma levels of diazepam and its metabolites indicated inter-and intrastrain variations in diazepam metabolism. We previously reported that the polymorphic expression of CYP2D3 in the liver caused the inter-and intrastrain differences in diazepam p-hydroxylation (Sakai et al, 2005). However, the mechanism underlying the polymorphic expression of CYP2D3 among the four rat strains remained to be described.…”

Section: Genetic Polymorphism Of Cyp2d3 In Ratsmentioning

confidence: 99%

“…The data of the metabolic activity were cited from Sakai et al (2005). CYP2D4 protein in liver microsomes (Sakai et al, 2005).…”

Section: Tablementioning

confidence: 99%

“…Moreover, using rat CYP2D isoforms expressed in yeast, the observation that diazepam p-hydroxylation is catalyzed by CYP2D3 was confirmed. Therefore, the polymorphic expression of CYP2D3 caused the inter-and intrastrain differences in diazepam p-hydroxylation among the four rat strains (Sakai et al, 2005). However, the question of what causes the polymorphic expression of CYP2D3 among the four rat strains remained to be solved.…”

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confidence: 99%

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Genetic Basis of Inter- and Intrastrain Differences in Diazepam p-Hydroxylation in Rats

Sakai

Saito²,

Sakamoto³

et al. 2009

Drug Metabolism and Disposition

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ABSTRACT:Diazepam (7-chloro-1,3-dihydro-1-methyl-5-phenyl-2H-1,4-benzodiazepin-2-one) is widely used as a sedative, hypnotic, and antianxiety drug. At low diazepam concentrations, p-hydroxylation is the major metabolic pathway in rat liver microsomes. However, there are marked (ϳ300-fold) inter-and intrastrain differences in the activity among Sprague-Dawley, Brown Norway, Dark Agouti, and Wistar rats. In our previous study, we determined that a deficiency of CYP2D3 protein, not CYP2D2, was responsible for the inter-and intrastrain differences in diazepam p-hydroxylation (Drug Metab Dispos 33:1657-1660, 2005). Quantitative real-time polymerase chain reaction (PCR) did not provide enough evidence to explain the inter-and intrastrain differences in the expression of CYP2D3 protein. Nucleotide sequence analysis revealed the insertion of a thymine in exon 8 of the CYP2D3 gene in the poor diazepam metabolizers. This single nucleotide mutation caused a shift in the reading frame and introduced a premature termination signal. It is noteworthy that the heme binding region, which is essential to maintain proper heme binding and active cytochrome P450 enzymes, was consequently deleted by the premature termination signal. In contrast, no mutation was detected in the CYP2D3 gene of extensive metabolizers. Thus, the truncated CYP2D3 must be a nonfunctional enzyme in poor metabolizers. In addition, we developed a convenient and specific genotyping assay using PCRrestriction, fragment-length polymorphism to distinguish homozygotes from heterozygotes. The genotyping gave results fully consistent with those of the inter-and intrastrain differences in diazepam p-hydroxylation.

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Human and environmental risk assessment of pharmaceuticals: differences, similarities, lessons from toxicology

et al. 2006

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The presence of human and veterinary pharmaceuticals in the environment has caused increasing concern due their effects on ecological receptors. Improving the risk assessment of these compounds necessitates a quantitative understanding of their metabolism and elimination in the target organism (toxicokinetics), particularly via the ubiquitous cytochrome P-450 (CYP) system and their mechanisms of toxicity (toxicodynamics). This review focuses on a number of pharmaceuticals and veterinary medicines of environmental concern, and the differences and similarities between ecological and human risk assessment. CYP metabolism is discussed with particular reference to its ubiquity in species of ecological relevance. The important issue of pharmaceutical mixtures is discussed to assess how emerging technologies such as ecotoxicogenomics may assist in moving towards a more mechanism-based environmental risk assessment of pharmaceuticals.

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Importance of Cyp2d3 in Polymorphism of Diazepam P-Hydroxylation in Rats

Cited by 10 publications

References 17 publications

Marked Strain Differences in the Pharmacokinetics of an α4β1 Integrin Antagonist, 4-[1-[3-Chloro-4-[N-(2-methylphenyl)-ureido]phenylacetyl]-(4 S)-fluoro-(2 S)-pyrrolidine-2-yl]-methoxybenzoic Acid (D01-4582), in Sprague-Dawley Rats Are Associated with Albumin Genetic Polymorphism

Marked Strain Differences in the Pharmacokinetics of an α4β1 Integrin Antagonist, 4-[1-[3-Chloro-4-[N-(2-methylphenyl)-ureido]phenylacetyl]-(4 S)-fluoro-(2 S)-pyrrolidine-2-yl]-methoxybenzoic Acid (D01-4582), in Sprague-Dawley Rats Are Associated with Albumin Genetic Polymorphism

Genetic Basis of Inter- and Intrastrain Differences in Diazepam p-Hydroxylation in Rats

Human and environmental risk assessment of pharmaceuticals: differences, similarities, lessons from toxicology

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