No abstract

AZD0837 single oral doses (15 - 750 mg) are well tolerated in healthy male subjects and exhibit favorable PK properties and reproducible effects on ex vivo coagulation time variables that support further clinical development.

Two clinical trials and a large set of in vitro transporter experiments were performed to investigate if the hepatobiliary disposition of the direct thrombin inhibitor prodrug AZD0837 is the mechanism for the drug-drug interaction with ketoconazole observed in a previous clinical study. In Study 1, [(3)H]AZD0837 was administered to healthy male volunteers (n = 8) to quantify and identify the metabolites excreted in bile. Bile was sampled directly from the jejunum by duodenal aspiration via an oro-enteric tube. In Study 2, the effect of ketoconazole on the plasma and bile pharmacokinetics of AZD0837, the intermediate metabolite (AR-H069927), and the active form (AR-H067637) was investigated (n = 17). Co-administration with ketoconazole elevated the plasma exposure to AZD0837 and the active form approximately 2-fold compared to placebo, which may be explained by inhibited CYP3A4 metabolism and reduced biliary clearance, respectively. High concentrations of the active form was measured in bile with a bile-to-plasma AUC ratio of approximately 75, indicating involvement of transporter-mediated excretion of the compound. AZD0837 and its metabolites were further investigated as substrates of hepatic uptake and efflux transporters in vitro. Studies in MDCK-MDR1 cell monolayers and P-glycoprotein (P-gp) expressing membrane vesicles identified AZD0837, the intermediate, and the active form as substrates of P-gp. The active form was also identified as a substrate of the multidrug and toxin extrusion 1 (MATE1) transporter and the organic cation transporter 1 (OCT1), in HEK cells transfected with the respective transporter. Ketoconazole was shown to inhibit all of these three transporters; in particular, inhibition of P-gp and MATE1 occurred in a clinically relevant concentration range. In conclusion, the hepatobiliary transport pathways of AZD0837 and its metabolites were identified in vitro and in vivo. Inhibition of the canalicular transporters P-gp and MATE1 may lead to enhanced plasma exposure to the active form, which could, at least in part, explain the clinical interaction with ketoconazole.

No abstract

Analytical methods were developed for the determination of six metabolites of lesogaberan to be used in quantitative determinations of metabolites according to the guidelines of Metabolites in Safety Testing. The γ-amino butyric acid type B receptor agonist lesogaberan and its metabolites are small polar molecules and hydrophilic interaction liquid chromatography was found to be a suitable separation mode. The samples were prepared using protein precipitation and negative electrospray ionization tandem mass spectrometry was used for detection. Initially, exploratory methods for six metabolites were set up for analysis of human plasma samples taken after repeated administration of a high oral dose of lesogaberan. The purpose was to establish which metabolites were present at concentrations significant for further investigation. Four of the six metabolites were then found at clearly detectable concentrations. The analytical methods for these four metabolites were further elaborated and then taken through a qualification procedure, which showed acceptable accuracy (86-114%), precision (<9%) and good linearity in the range 0.03-5 µmol/L. No interferences were seen from endogenous plasma components.