Marked strain differences in the pharmacokinetics of an α4β1 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 rats are associated with albumin genetic polymorphism

Strain differences in pharmacokinetics of an alpha(4)beta(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.