RT Journal Article
SR Electronic
T1 Identification of UDP-Glucuronosyltransferases Responsible for the Glucuronidation of Darexaban, an Oral Factor Xa Inhibitor, in Human Liver and Intestine
JF Drug Metabolism and Disposition
JO Drug Metab Dispos
FD American Society for Pharmacology and Experimental Therapeutics
SP 276
OP 282
DO 10.1124/dmd.111.042614
VO 40
IS 2
A1 Toshifumi Shiraga
A1 Kanako Yajima
A1 Kenta Suzuki
A1 Katsuhiro Suzuki
A1 Tadashi Hashimoto
A1 Takafumi Iwatsubo
A1 Aiji Miyashita
A1 Takashi Usui
YR 2012
UL http://dmd.aspetjournals.org/content/40/2/276.abstract
AB Darexaban maleate is a novel oral direct factor Xa inhibitor, which is under development for the prevention of venous thromboembolism. Darexaban glucuronide was the major component in plasma after oral administration of darexaban to humans and is the pharmacologically active metabolite. In this study, we identified UDP-glucuronosyltransferases (UGTs) responsible for darexaban glucuronidation in human liver microsomes (HLM) and human intestinal microsomes (HIM). In HLM, the Km value for darexaban glucuronidation was >250 μM. In HIM, the reaction followed substrate inhibition kinetics, with a Km value of 27.3 μM. Among recombinant human UGTs, UGT1A9 showed the highest intrinsic clearance for darexaban glucuronidation, followed by UGT1A8, -1A10, and -1A7. All other UGT isoforms were inactive toward darexaban. The Km value of recombinant UGT1A10 for darexaban glucuronidation (34.2 μM) was comparable to that of HIM. Inhibition studies using typical UGT substrates suggested that darexaban glucuronidation in both HLM and HIM was mainly catalyzed by UGT1A8, -1A9, and -1A10. Fatty acid-free bovine serum albumin (2%) decreased the unbound Km for darexaban glucuronidation from 216 to 17.6 μM in HLM and from 35.5 to 18.3 μM in recombinant UGT1A9. Recent studies indicated that the mRNA expression level of UGT1A9 is extremely high among UGT1A7, -1A8, -1A9, and -1A10 in human liver, whereas that of UGT1A10 is highest in the intestine. Thus, the present results strongly suggest that darexaban glucuronidation is mainly catalyzed by UGT1A9 and UGT1A10 in human liver and intestine, respectively. In addition, UGT1A7, -1A8, and -1A9 play a minor role in human intestine.