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  • 1
    Publication Date: 2013-04-16
    Description: Olmesartan medoxomil (OM) is a prodrug-type angiotensin II type 1 receptor antagonist. OM is rapidly converted into its active metabolite olmesartan by multiple hydrolases in humans, and we recently identified carboxymethylenebutenolidase homolog (CMBL) as one of the OM bioactivating hydrolases. In the present study, we further investigated the interindividual variability of mRNA and protein expression of CMBL and OM-hydrolase activity using 40 individual human liver and 30 intestinal specimens. In the intestinal samples, OM-hydrolase activity strongly correlated with the CMBL protein expression, clearly indicating that CMBL is a major contributor to the prodrug bioactivation in human intestine. The protein and activity were highly distributed in the proximal region (duodenum and jejunum) and decreased to the distal region of the intestine. Although there was high interindividual variability (16-fold) in both the protein and activity in the intestinal segments from the duodenum to colon, the interindividual variability in the duodenum and jejunum was relatively small (3.0- and 2.4-fold, respectively). In the liver samples, the interindividual variability in the protein and activity was 4.1- and 6.8-fold, respectively. No sex differences in the protein and activity were shown in the human liver or intestine. A genetically engineered Y155C mutant of CMBL, which was caused by a single nucleotide polymorphism rs35489000, showed significantly lower OM-hydrolase activity than the wild-type protein although no minor allele was genotyped in the 40 individual liver specimens.
    Print ISSN: 0090-9556
    Electronic ISSN: 1521-009X
    Topics: Chemistry and Pharmacology , Medicine
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  • 2
    Publication Date: 2014-03-02
    Description: Edoxaban (the free base of DU-176b), an oral direct factor Xa inhibitor, is mainly excreted unchanged into urine and feces. Because active membrane transport processes such as active renal secretion, biliary excretion, and/or intestinal secretion, and the incomplete absorption of edoxaban after oral administration have been observed, the involvement of drug transporters in the disposition of edoxaban was investigated. Using a bidirectional transport assay in human colon adenocarcinoma Caco-2 cell monolayers, we observed the vectorial transport of [ 14 C]edoxaban, which was completely inhibited by verapamil, a strong P-glycoprotein (P-gp) inhibitor. In an in vivo study, an increased distribution of edoxaban to the brain was observed in Mdr1a/1b knockout mice when compared with wild-type mice, indicating that edoxaban is a substrate for P-gp. However, there have been no observations of significant transport of edoxaban by renal or hepatic uptake transporters, organic anion transporter (OAT)1, OAT3, organic cation transporter (OCT)2, or organic anion transporting polypeptide (OATP)1B1. Edoxaban exhibited no remarkable inhibition of OAT1, OAT3, OCT1, OCT2, OATP1B1, OATP1B3, or P-gp up to 30 μ M; therefore, the risk of clinical drug–drug interactions due to any edoxaban-related transporter inhibition seems to be negligible. Our results demonstrate that edoxaban is a substrate of P-gp but not of other major uptake transporters tested. Because metabolism is a minor contributor to the total clearance of edoxaban and strong P-gp inhibitors clearly impact edoxaban transport, the P-gp transport system is a key factor for edoxaban’s disposition.
    Print ISSN: 0090-9556
    Electronic ISSN: 1521-009X
    Topics: Chemistry and Pharmacology , Medicine
    Location Call Number Limitation Availability
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