Identification of the human cytochrome P450s responsible for the<b><i>in vitro</i></b>metabolism of a leukotriene B4 receptor antagonist, CP-195,543

Khojasteh-Bakht, Siamak C.; Rossulek, Michelle; Fouda, Hassan G.; Prakash, Chandra

doi:10.1080/00498250310001646362

Cited by 3 publications

(3 citation statements)

References 14 publications

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“…As observed by the relative growth of the peaks at m / z = 472 versus 488, the first oxidation event appears to be more rapid than the second. We hypothesize that 1 undergoes rapid hydroxylation at either the benzylic or thiophene-2-methylamine linking carbons, positions that are thought to stabilize radical intermediates (Figure D). As reported in Table S1, analogues with R 1 substituted with p -chlorophenyl showed greater in vitro metabolic stability ( 2bf – 2bj ), likely because of absence of the benzylic hydroxylation site and also because of occupation of the para-position, which is a known site of P450 metabolism .…”

Section: Resultsmentioning

confidence: 99%

Nanomolar Potency and Metabolically Stable Inhibitors of Kidney Urea Transporter UT-B

et al. 2012

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Urea transporters, which include UT-B in kidney microvessels, are potential targets for development of drugs with a novel diuretic (‘urearetic’) mechanism. We recently identified, by high-throughput screening, a triazolothienopyrimidine UT-B inhibitor, 1, that selectively and reversibly inhibited urea transport with IC50 = 25.1 nM and reduced urinary concentration in mice (Yao et al. J. Am. Soc. Nephrol., in press). Here, we analyzed 273 commercially available analogues of 1 to establish a structure–activity series and synthesized a targeted library of 11 analogues to identify potent, metabolically stable UT-B inhibitors. The best compound, {3-[4-(1,1-difluoroethyl)benzenesulfonyl]thieno[2,3-e][1,2,3]triazolo[1,5-a]pyrimidin-5-yl}thiophen-2-ylmethylamine, 3k, had IC50 of 23 and 15 nM for inhibition of urea transport by mouse and human UT-B, respectively, and ~40-fold improved in vitro metabolic stability compared to 1. In mice, 3k accumulated in kidney and urine and reduced maximum urinary concentration. Triazolothienopyrimidines may be useful for therapy of diuretic-refractory edema in heart and liver failure.

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Section: Resultsmentioning

confidence: 99%

Nanomolar Potency and Metabolically Stable Inhibitors of Kidney Urea Transporter UT-B

et al. 2012

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“…Most of the CYP3A4 substrates are also metabolized by CYP3A5 (Williams et al, 2002). However, some differences have been reported in enzymatic properties of CYP3A4 and CYP3A5, including substrate specificity and inhibition (Khojasteh-Bakht et al, 2003;Emoto and Iwasaki, 2006). In the current study, it was found that N-oxide (M5) and its N-dealkylated metabolite (M19) were formed only by CYP3A4 but not CYP3A5.…”

Section: In Vitro Metabolism Of a Pyridinyl Sulfonamide Analogmentioning

confidence: 99%

CYP2C8- and CYP3A-MediatedC-Demethylation of (3-{[(4-tert-Butylbenzyl)-(pyridine-3-sulfonyl)-amino]-methyl}-phenoxy)-acetic Acid (CP-533,536), an EP2 Receptor-Selective Prostaglandin E2 Agonist: Characterization of Metabolites by High-Resolution Liquid Chromatography-Tandem Mass Spectrometry and Liquid Chromatography/Mass Spectrometry-Nuclear Magnetic Resonance

Prakash¹,

Wang²,

O’Connell³

et al. 2008

Drug Metab Dispos

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CP-533,536, (3-{[(4-tert-butyl-benzyl)-(pyridine-3-sulfonyl)-amino]-methyl}-phenoxy)-acetic acid (1), an EP2 receptor-selective prostaglandin E2 agonist, is being developed to aid in the healing of bone fractures. To support the development of this program, in vitro metabolism of 1 was investigated in human liver microsomes and major recombinant human cytochrome P450 (P450) isoforms. 1 was metabolized in vitro by at least three recombinant human P450s: CYP3A4, CYP3A5, and CYP2C8. The turnover of 1 was NADPH-dependent and was completely inhibited by ketoconazole and quercetin in the CYP3A4/5 and CYP2C8 incubations, respectively. The major metabolic pathways were caused by oxidation of the tert-butyl moiety to form the -hydroxy metabolite (M4), oxidation of the pyridine moiety, and/or N-dealkylation of the methylphenoxy acetic acid moiety. The alcohol metabolite M4 was further oxidized to the corresponding carboxylic acid M3. In addition to these pathways, three unusual metabolites (M22, M23, and M26) resulting from C-demethylation of the tert-butyl group were identified using high-resolution liquid chromatography/tandem mass spectrometry and liquid chromatography/mass spectrometry/ NMR. The C-demethylated metabolites were not detected on incubation of carboxylic acid metabolite M3 with either human liver microsomes or CYP3A/2C8 isoforms, suggesting that these metabolites were not derived from decarboxylation of M3. A possible mechanism for C-demethylation may involve the oxidation of M4 to form an aldehyde metabolite (M24), followed by P450-mediated deformylation, to give an unstable carbon-centered radical and formic acid. The carbon-centered radical intermediate then undergoes either oxygen rebound to form an alcohol metabolite M23 or hydrogen abstraction leading to an olefin metabolite M26.It has been well documented that EP2-selective prostaglandin E2 (PGE2) agonists, when delivered locally to the periosteal surface or the marrow cavity of bones, increase cortical and cancellous bone formation without the systemic side effects observed with PGE2 (Breyer et al., 2001). Compound 1 (Fig. 1) is a nonprostanoid agonist of the prostaglandin EP2 receptor subtype of PGE2 with significant local bone anabolic activity. It binds to the EP2 receptor with high affinity and selectivity and initiates cAMP signaling via an EP2 receptor-mediated signaling pathway. In in vivo studies, 1 enhanced bone fracture healing in rat and dog fracture models. Furthermore, 1 induced new bone formation and healed critical-sized segmental defects of long bones in the dog (Paralkar et al., 2003). Therefore, it offers a promising therapeutic alternative for the enhancement of bone healing and treatment of bone defects and fractures in humans.Elucidation of biotransformation pathways of a drug candidate in animals and humans, and evaluation of pharmacological and toxicological consequences of its metabolites are very critical to pharmaceutical development and compound progression (Kostiainen et al.,

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“…[8][9][10][11][12] However, in these reactions, a minor contribution of CYP3A5 may be demonstrated in the future when detection methods for the metabolite have been improved. In contrast, reactions which are predominantly catalyzed by CYP3A5 have not been reported.…”

Section: Metabolic Activity Of Cyp3a4 and Cyp3a5mentioning

confidence: 99%

Comparison of the Contributions of Cytochromes P450 3A4 and 3A5 in Drug Oxidation Rates and Substrate Inhibition

Niwa

Murayama

Yamazaki

2010

JOURNAL OF HEALTH SCIENCE

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A meta-analysis was performed on the reported literature regarding followings. First, values of the MichaelisMenten constants (K m ), maximal velocities (V max ), and intrinsic clearance (V max /K m ) and the metabolic activities mediated by human cytochrome P450 3A4 and/or 3A5; second, inhibition constants (K i ); and third, maximum inactivation rate constants (k inact ) to establish the contribution of P450 3A5 to drug metabolism. At least 120 of the 127 metabolic reactions investigated (> 94%) were catalyzed by P450 3A4 and by P450 3A5. In the 73 metabolic reactions for which data were available, the mean P450 3A5/P450 3A4 ratios of K m , V max , and V max /K m values were 1.93, 1.25, and 1.20, respectively, but the median ratios were 1.17, 0.64, and 0.56, respectively. In 14-18% of the metabolic reactions, the V max and V max /K m values for P450 3A5 were more than twice those for P450 3A4. The K i values for P450 3A5 were on average approximately 5 times those for P450 3A4. Five of 13 mechanism-based inhibitors of P450 3A4 (38%) did not exhibit similar mechanism-based inhibition of P450 3A5. These collective findings give insight into the contribution of polymorphic P450 3A5 to drug metabolism and adverse drug interactions.

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Identification of the human cytochrome P450s responsible for thein vitrometabolism of a leukotriene B4 receptor antagonist, CP-195,543

Cited by 3 publications

References 14 publications

Nanomolar Potency and Metabolically Stable Inhibitors of Kidney Urea Transporter UT-B

Nanomolar Potency and Metabolically Stable Inhibitors of Kidney Urea Transporter UT-B

Comparison of the Contributions of Cytochromes P450 3A4 and 3A5 in Drug Oxidation Rates and Substrate Inhibition

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