Determination of 2-(3-benzoyl)-4-hydroxy-1,1-dioxo-2H-1,2-benzothiazine-2-yl-1-phenylethanone by liquid chromatography-tandem mass spectrometry.

2-(3-Benzoyl)-4-hydroxy-1,1-dioxo-2H-1,2-benzothiazine-2-yl-1-phenylethanone (KR-66344), a 11ß-hydroxysteroid dehydrogenase type 1 (11ß-HSD1) inhibitor, is newly developed for the control of type 2 diabetes mellitus (T2DM) and metabolic syndrome. A method for the determination of KR-66344 in rat plasma was developed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS-MS) to evaluate the pharmacokinetics of KR-66344. Plasma samples were processed by a liquid-liquid extraction method with ethyl acetate and introduced onto the LC-MS-MS system. The analyte and imipramine (internal standard) were analyzed by multiple reaction monitoring based on transitions at m/z 420.1 → 105.0 and 282.2 → 86.0, respectively. The calibration curve was linear (r = 0.9993) over the concentration range of 1.0-1,000 ng/mL. The mean recovery values for KR-66344 and imipramine were 83.8 and 86.2%, respectively. The mean inter-day and intra-day assay precision values were 3.9 and 2.4%, respectively. KR-66344 was stable under various handling and storage conditions. This developed method was applied to a pharmacokinetic study after the oral administration of KR-66344 in rats. The concentration of KR-66344 was readily measurable in rat plasma up to 24 h post-dose after an oral administration, suggesting that current assay is applicable to pharmacokinetic studies for KR-66344.

Preclinical pharmacokinetic characterization of 2-(4-(4-(5-(2-phenyl-5-(trifluoromethyl)oxazole-4-carboxamido)-1H-benzo[d]imidazol-2-yl)phenyl)cyclohexyl) acetic acid, a novel DGAT-1 inhibitor.

1. A novel diacylglyceride acyltransferase-1 (DGAT-1) inhibitor, 2-(4-(4-(5-(2-phenyl-5-(trifluoromethyl) oxazole-4-carboxamido)-1H-benzo[d]imidazol-2-yl)phenyl)cyclohexyl) acetic acid (KR-69232), was synthesized for a potential therapeutic use against several metabolic disorders, such as obesity, insulin resistance, and type II diabetes, characterized by excessive triglycerides (TGs) in the blood. 2. The half-lives against phase I metabolism were measured as 75.3 ± 20.9 min and over 120 min in rat and human liver microsomes, respectively. In Caco-2 cell monolayers, extremely low permeability (<0.13 × 10⁻6cm/s) was seen in the absorptive direction, predicting limited intestinal absorption of KR-69232. This compound was highly bound to rat and human plasma proteins (>99.8%). 3. With the intravenous administration of KR-69232 in rats (1, 2, and 5 mg/kg), non-linear kinetics were observed at the highest dose, with significantly higher systemic clearance, higher volume of distribution, and lower dose-normalized AUC. Following oral administration, it exhibited low bioavailability (<10%) and was absorbed slowly (T(max), 3.8-5.2 h) over the dose range. We also confirmed that considerable KR-69232 remained in the intestine at T(max), demonstrating its limited absorption into the systemic circulation.

Determination of a novel TAZ modulator, 2-butyl-5-methyl-6-(pyridine-3-yl)-3-[2'-(1H-tetrazole-5-yl)-biphenyl-4-ylmethyl]-3H imidazo[4,5-b]pyridine] (TM-25659) in rat plasma by liquid chromatography-tandem mass spectrometry.

TM-25659 compound, a novel TAZ modulator, is developed for the control of bone loss and obesity. TAZ is known to bind to a variety of transcription factors to control cell differentiation and organ development. A selective and sensitive method was developed for the determination of TM-25659 concentrations in rat plasma. The drug was measured by liquid chromatography-tandem mass spectrometry after liquid-liquid extraction with ethyl acetate. TM-25659 and the internal standard imipramine were separated on a Hypersil GOLD C18 column with a mixture of acetonitrile-ammonium formate (10 mM) (90:10, v/v) as the mobile phase. The ions m/z 501.2→207.2 for TM-25659 and m/z 281.0→86.0 for imipramine in multiple reaction monitoring mode were used for the quantitation. The calibration range was 0.1-100 µg/ml with a correlation coefficient greater than 0.99. The lower limit of quantitation of TM-25659 in rat plasma was 0.1 µg/ml. The percent recoveries of TM-25659 and imipramine were 98.6% and 95.7% from rat plasma, respectively. The intra- and inter-batch precisions were 3.17-15.95% and the relative error was 0.38-10.82%. The developed assay was successfully applied to a pharmacokinetic study of TM-25659 administered intravenously (10 mg/kg) to rats.

Dose-independent pharmacokinetics of a new peroxisome proliferator-activated receptor-γ agonist, KR-62980, in Sprague-Dawley rats and ICR mice.

The pharmacokinetics of a novel peroxisome proliferator-activated receptor-γ agonist, KR-62980, were characterized in vitro with respect to liver metabolic stability, cell permeability, and plasma protein binding and in vivo using Sprague-Dawley rats and ICR mice. The metabolic half-life of 0.1-10 µM KR-62980 was 11.5-15.2 min in rat liver microsomes and 25.8-28.8 min in human liver microsomes. KR-62980 showed high permeability across MDCK cell monolayers, with apparent permeability coefficients of 20.4 × 10(-6) to 30.8 × 10(-6) cm/sec. The plasma protein binding rate of KR-62980 was 89.4%, and most was bound to serum albumin. After intravenous administration of KR-62980 (2 mg/kg), the systemic clearance was 2.50 L/h/kg, and the volume of distribution at steady-state was 9.16 L/kg. The bioavailability after oral administration was approximately 60.9%. The dose-normalized AUC values were 0.50 ± 0.09, 0.41 ± 0.20, and 0.62 ± 0.08 h · µg/mL after oral administration of 2, 5, and 10 mg/kg KR-62980, respectively, showing no dose-dependency. The in vivo pharmacokinetic parameters in ICR mice were also dose independent. These data suggest that KR-62980 is not significantly dose dependent in rats or mice, although it may disappear rapidly from the systemic circulation via metabolism in the liver.