Determination of a novel phosphodiesterase4 inhibitor, 3-[1-(3cyclopropylmethoxy-4-difluoromethoxybenzyl)-1H-pyrazol-3-yl]-benzoic acid (PDE-423) in rat plasma using liquid chromatography-tandem mass spectrometry.

A method for determining a novel phosphodiesterase-4 inhibitor, 3-[1-(3cyclopropylmethoxy-4-difluoromethoxybenzyl)-1H-pyrazol-3-yl]-benzoic acid (PDE-423), in rat plasma was developed and validated using liquid chromatography-tandem mass spectrometry for further pharmacokinetic study for development as a novel anti-asthmatic drug. PDE-423 in the concentration range of 0.02-10 µg/mL was linear with a correlation coefficient of >0.99, and the mean intra- and inter-assay precisions of the assay were 7.50 and 3.86%, respectively. The validated method was used successfully for a pharmacokinetic study of PDE-423 in rats.

Determination of a novel diacylglycerol acyltransferase 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) in rat plasma using liquid chromatography-tandem mass spectrometry and its application to a pharmacokinetic study.

A liquid chromatography-tandem mass spectrometry method was developed and validated for the quantification of KR-69232, a diacyltransferase 1 inhibitor, in rat plasma. KR-69232 in the concentration range of 0.004-4 µg/mL was linear. The intra-and inter-day precision and accuracy were acceptable (<20%). KR-69232 was stable under various storage and handling conditions. The method was applied successfully in a pharmacokinetic study of KR-69232 in rats.

Pharmacokinetic characterization of the novel TAZ modulator TM-25659 using a multicompartment kinetic model in rats and a possibility of its drug-drug interactions in humans.

This study evaluated the pharmacokinetics of the novel TAZ modulator TM-25659 in rats following intravenous and oral administration at dose ranges of 0.5-5 mg/kg and 2-10 mg/kg, respectively. Plasma protein binding, plasma stability, liver microsomal stability, CYP inhibition, and transport in Caco-2 cells were also evaluated. After intravenous injection, systemic clearance, steady-state volumes of distribution, and half-life were dose-independent, with values ranging from 0.434-0.890 mL · h(-1) · kg(-1), 2.02-4.22 mL/kg, and 4.60-7.40 h, respectively. Mean absolute oral bioavailability was 50.9% and was not dose dependent. Recovery of TM-25659 was 43.6% in bile and <1% in urine. In pharmacokinetic modeling studies, the three-compartment (3C) model was appropriate for understanding these parameters in rats. TM-25659 was stable in plasma. Plasma protein binding was approximately 99.2%, and was concentration-independent. TM-25659 showed high permeation of Caco-2 cells and did not appear to inhibit CYP450. TM-25659 was metabolized in phase I and II steps in rat liver microsomes. In conclusion, the pharmacokinetics of TM-25659 was characterized for intravenous and oral administration at doses of 0.5-5 and 2-10 mg/kg, respectively. TM-25659 was eliminated primarily by hepatic metabolism and urinary excretion.

Determination of PF-04620110, a novel inhibitor of diacylglycerol acyltransferase-1, in rat plasma using liquid chromatography-tandem mass spectrometry and its application in pharmacokinetic studies.

In this study, we developed a method for the determination of PF-04620110 (2-{(1r,4r)-4-[4-(4-amino-5-oxo-7,8-dihydropyrimido[5,4-f][1,4]oxazepin-6(5H)-yl)phenyl]cyclohexyl}acetic acid), a novel diacylglycerol acyltransferase 1 (DGAT-1) inhibitor, in rat plasma and validated it using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Rat plasma samples were processed following a protein precipitation method by using acetonitrile and were then injected into an LC-MS/MS system for quantification. PF-04620110 and imipramine (internal standard) were separated using a Hypersil Gold C18 column, with a mixture of acetonitrile and 10 mm ammonium formate (90:10, v/v) as the mobile phase. The ion transitions monitored in positive-ion mode [M + H](+) of multiple-reaction monitoring were m/z 397.0 → 260.2 for PF-04620110 and m/z 280.8 → 86.0 for imipramine. The detector response was specific and linear for PF-04620110 at concentrations within the range 0.05-50 µg/mL and the signal-to-noise ratios for the samples were ≥10. The intra- and inter-day precision and accuracy of the method matched the acceptance criteria for assay validation. PF-04620110 was stable under various processing and/or handling conditions. PF-04620110 concentrations in the rat plasma samples could be measured up to 24 h after intravenous or oral administration of PF-04620110, suggesting that the assay is useful for pharmacokinetic studies in rats.

Determination of mesoridazine by liquid chromatography-tandem mass spectrometry and its application to pharmacokinetic study in rats.

The object of the present study was to develop and validate an assay method of mesoridazine in rat plasma using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Plasma samples from rats were prepared by simple protein precipitation and injected onto the LC-MS/MS system for quantification. Mesoridazine and chlorpromazine as an internal standard (IS) were separated by a reversed phase C18 column. A mobile phase was composed of 10mM ammonium formate in water and acetonitrile (ACN) (v/v) by a linear gradient system, increasing the percentage of ACN from 2% at 0.4min to 98% at 2.5min with 4min total run time. The ion transitions monitored in positive-ion mode [M+H](+) of multiple-reaction monitoring (MRM) were m/z 387>126 for mesoridazine and m/z 319>86 for IS. The detector response was specific and linear for mesoridazine at concentrations within the range 0.001-4µg/ml and the correlation coefficient (R(2)) was greater than 0.999 and the signal-to-noise ratios for the samples were ≥10. The intra- and inter-day precision and accuracy of the method were determined to be within the acceptance criteria for assay validation guidelines. The matrix effects were approximately 101 and 99.5% from rat plasma for mesoridazine and chlorpromazine, respectively. Mesoridazine was stable under various processing and/or handling conditions. Mesoridazine concentrations were readily measured in rat plasma samples after intravenous and oral administration. This assay method can be practically useful to the pharmacokinetic and/or toxicokinetic studies of mesoridazine.

Determination of 2-aryl-7(3',4'-dialkoxyphenyl)-pyrazolo [1,5-alpha] pyrimidine, a novel phosphodiesterase-4 inhibitor, in rat plasma by liquid chromatography-tandem mass spectrometry.

A method for assaying a novel phosphodiesterase-4 inhibitor, 2-aryl-7(3',4'-dialkoxyphenyl)-pyrazolo [1,5-alpha] pyrimidine (PDE-310), was developed and validated in rat plasma using liquid chromatography-tandem mass spectrometry (LC-MS-MS). Rat plasma samples were processed by liquid-liquid extraction with ethyl acetate and injected onto the LC-MS-MS system for quantification. PDE-310 and imipramine (i.e., internal standard) were separated using a Gemini C18 column with mixture of acetonitrile and 0.1% formic acid (70:30, v/v) as the mobile phase. The ion transitions monitored were m/z 425.0 → 331.0 for PDE-310 and m/z 281.3 → 86.1 for imipramine in the multiple-reaction monitoring mode. The detector response was specific and linear for PDE-310 concentrations in the range of 0.1-50 µg/mL. The intra-day and inter-day precision and accuracy of the method were determined to be within the acceptance criteria for assay validation guidelines. The recoveries were approximately 85.7 and 88.2% from rat plasma for PDE-310 and imipramine, respectively. PDE-310 was stable under various processing and handling conditions. PDE-310 concentrations were readily measured in rat plasma samples up to 8 h after an intravenous administration of PDE-310, suggesting that the assay is practically useful.

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.