title: Influence of albumin on enantioselective local disposition of BOF-4272, a xanthine oxidase inhibitor with chiral sulfoxide, in rat liver.
abstract: 8-(3-Methoxy-4-phenylsulfinylphenyl) pyrazolo[1,5-a]-1,3,5-triazine-4(1H)-one (BOF-4272) blocks xanthine oxidase/xanthine dehydrogenase in the liver. BOF-4272 with a sulfoxide chiral center includes R(+)- and S(-)-enantiomers. The enantioselectivity in the global disposition of BOF-4272 can be attributed to that in the local disposition of organs, especially the liver. Thus, the enantioselectivity in the hepatic local disposition of BOF-4272 was compared between R- and S-enantiomers by a hepatic perfusion experiment with a pulse input into the portal vein. The influence of perfusate albumin on the enantioselective local disposition was also investigated. The elution time profile of each BOF-4272 enantiomer from the liver into the hepatic vein was measured at four different bovine serum albumin (BSA) concentrations (0, 0.25, 1.0 and 4.0%) in the perfusate at 37 and 4 degrees C. A crossover test was carried out for R- and S-enantiomers using one rat liver. In the absence of perfusate BSA at 37 degrees C, hepatic extraction ratios (E[H]) of R- and S-enantiomers of BOF-4272 were 75.6 +/- 4.3% and 71.7 +/- 3.3%, respectively, which were statistically the same. In the presence of 4.0% BSA at 37 degrees C, E(H) values of R- and S-enantiomers were 31.7 +/- 4.6% and 19.6 +/- 3.8%, respectively, which demonstrated that E(H) of R-enantiomer was significantly greater than that of S-enantiomer (p < 0.001). In the absence and presence of perfusate BSA at 4 degrees C, there was no significant difference in E(H) between S- and R-enantiomers. An amplification of stereoselectivity with albumin was observed by the perfusion experiment using BOF-4272 enantiomers.
authors.affiliation: Laboratory of Drug Metabolism Research, Naruto Research Institute, Otsuka Pharmaceutical Factory, Inc., Tokushima, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Nishimura
authors.forename: K
authors.initials: K
authors.lastname: Yamaoka
authors.forename: S
authors.initials: S
authors.lastname: Naito
authors.forename: T
authors.initials: T
authors.lastname: Nakagawa
mesh_terms: D000418:Albumins / Q000378:metabolism*; D000818:Animals; D004791:Enzyme Inhibitors / Q000493:pharmacokinetics*; D066298:In Vitro Techniques; D008099:Liver / Q000378:metabolism*; D008297:Male; D011485:Protein Binding; D051381:Rats; D017208:Rats, Wistar; D012710:Serum Albumin, Bovine / Q000378:metabolism; D013056:Spectrophotometry, Ultraviolet; D013237:Stereoisomerism; D013454:Sulfoxides / Q000378:metabolism; D014227:Triazines / Q000493:pharmacokinetics*; D014969:Xanthine Oxidase / Q000037:antagonists & inhibitors*
chemical_list: D000418:Albumins; D004791:Enzyme Inhibitors; D013454:Sulfoxides; D014227:Triazines; D012710:Serum Albumin, Bovine; C072977:BOF 4272; D014969:Xanthine Oxidase