Abstract
Edaravone was launched in Japan in 2001 and was the first neuroprotectant developed for the treatment of acute cerebral infarction. Edaravone is mainly eliminated as glucuronide conjugate in human urine (approximately 70%), but the mechanism involved in the elimination pathway remains unidentified. We investigated the glucuronidation of edaravone in human liver microsomes (HLM) and human kidney microsomes (HKM) and identified the major hepatic and renal UDP-glucuronosyltransferases (UGTs) involved. As we observed, edaravone glucuronidation in HLM and HKM exhibited biphasic kinetics. The intrinsic clearance of glucuronidation at high-affinity phase (CLint1) and low-affinity phase (CLint2) were 8.4 ± 3.3 and 1.3 ± 0.2 μl · min−1 · mg−1, respectively, for HLM and were 45.3 ± 8.2 and 1.8 ± 0.1 μl · min−1 · mg−1, respectively, for HKM. However, in microsomal incubations contained with 2% bovine serum albumin, CLint1 and CLint2 were 16.4 ± 1.2 and 3.7 ± 0.3 μl · min−1 · mg−1, respectively, for HLM and were 78.5 ± 3.9 and 3.6 ± 0.5 μl · min−1 · mg−1, respectively, for HKM. Screening with 12 recombinant UGTs indicated that eight UGTs (UGT1A1, UGT1A6, UGT1A7, UGT1A8, UGT1A9, UGT1A10, UGT2B7, and UGT2B17) produced a significant amount of glucuronide metabolite. Thus, six UGTs (UGT1A1, UGT1A6, UGT1A7, UGT1A9, UGT2B7, and UGT2B17) expressed in human liver or kidney were selected for kinetic studies. Among them, UGT1A9 exhibited the highest activity (CLint1 = 42.4 ± 9.5 μl · min−1 · mg−1), followed by UGT2B17 (CLint = 3.3 ± 0.4 μl · min−1 · mg−1) and UGT1A7 (CLint = 1.7 ± 0.2 μl · min−1 · mg−1). Inhibition study found that inhibitor of UGT1A9 (propofol) attenuated edaravone glucuronidation in HLM and HKM. In addition, edaravone glucuronidation in a panel of seven HLM was significantly correlated (r = 0.9340, p = 0.0021) with propofol glucuronidation. Results indicated that UGT1A9 was the main UGT isoform involved in edaravone glucuronidation in HLM and HKM.
Footnotes
This work was supported by China “Creation of New Drugs ” Key Technology Projects [Grant 2009ZX09304-001]; and the Fundamental Research Funds for the Central Universities [Grant JKP2009007].
Article, publication date, and citation information can be found at http://dmd.aspetjournals.org.
ABBREVIATIONS:
- UGT
- UDP-glucuronosyltransferase
- HKM
- human kidney microsomes
- LC/MS/MS
- liquid chromatography/tandem mass spectrometry
- UDPGA
- UDP-glucuronic acid
- MS/MS
- tandem mass spectrometry
- HLM
- human liver microsomes
- IS
- internal standard
- BSA
- bovine serum albumin.
- Received October 18, 2011.
- Accepted January 11, 2012.
- Copyright © 2012 by The American Society for Pharmacology and Experimental Therapeutics
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