Yoon-Jee Chae

Pharmacokinetics of lurasidone, a novel atypical anti-psychotic drug, in rats

This study aimed to characterise the pharmacokinetics of lurasidone, a new atypical anti-psychotic drug, in rats after intravenous and oral administration at dose range 0.5–2.5 and 2.5–10 mg/kg, respectively. Moreover, tissue distribution, liver microsomal stability and plasma protein binding were estimated. After intravenous injection, systemic clearance, steady-state volumes of distribution and half-life remained unaltered as a function of dose with values in the range 22.1–27.0 mL/min/kg, 2,380–2,850 mL/kg and 229–267 min, respectively. Following oral administration, absolute oral bioavailability was not dose dependent with approximately 23%. The recoveries of lurasidone in urine and bile were 0.286% and 0.0606%, respectively. Lurasidone was primarily distributed to nine tissues (brain, liver, kidneys, heart, spleen, lungs, gut, muscle and adipose) and tissue-to-plasma ratios of lurasidone were ranged from 1.06 (brain) to 9.16 (adipose). Further, lurasidone was unstable in rat liver microsome and the plasma protein binding of lurasidone was concentration independent with approximately 99.6%. In conclusion, lurasidone showed dose-independent pharmacokinetics at an intravenous dose of 0.5–2.5 mg/kg and an oral dose of 2.5–10 mg/kg. Lurasidone was primarily distributed to nine tissues and appeared to be primarily eliminated by its metabolism.

QUANTIFICATION OF CILNIDIPINE IN HUMAN PLASMA BY LIQUID CHROMATOGRAPHY-MASS SPECTROMETRY

A liquid chromatography-mass spectrometry (LC-MS) assay was developed and validated for the quantification of cilnidipine, a calcium channel antagonist, in human plasma. Plasma samples were processed by liquid-liquid extraction and the analyte, along with nimodipine (an internal standard), and analyzed using selected ion monitoring (SIM) for detection. The absolute extraction recovery was determined to be not less than 89.1% for various concentrations. The detector response was specific and linear for cilnidipine concentrations in the range of 0.5–50 ng/mL. Validation parameters, including inter-/intra-day precision and accuracy, were found to be within the acceptance criteria for assay validation guidelines. The analyte was stable under a variety of processing and handling conditions. Cilnidipine levels were readily measured in plasma samples up to 10 hr after an oral administration of 10 mg of a cilnidipine formulation in humans, suggesting that the assay can be used in routine analyses.

A strategy for reducing particulate contamination on opening glass ampoules and development of evaluation methods for its application

A single-dose glass ampoule was developed for ease of administration. When glass ampoules are opened, resulting in contamination by particulate matter. Reducing its contamination may minimize the risk in patients due to particulates. This study reports on an attempt to reduce insoluble particulate contamination by developing methods for the precise measurement of this. A vacuum machine (VM) was used to reduce the level of insoluble particulate contamination, and a microscopy, scanning electron microscopy-energy dispersive X-ray spectrometer (SEM-EDS) and inductively coupled plasma-atomic emission spectrometer (ICP-AES) were used to evaluate the level of reduction. The method permitted the insoluble particle content to be reduced by up to 87.8 and 89.3% after opening 1 and 2 mL-ampoules, respectively. The morphology of the glass particulate contaminants was very sharp and rough, a condition that can be harmful to human health. The total weight of glass particles in the opened ampoules was determined to be 104 ± 72.9 µg and 30.5 ± 1.00 µg after opening 1 and 2 mL-ampoules when the VM was operated at highest power. The total weights were reduced to 53.6 and 50.6%, respectively for 1 and 2 mL-ampoules, compared to opening by hand. The loss of ampoule contents on opening by the VM was 6.50 and 4.67% for 1 and 2 mL-ampoules, respectively. As a result, the VM efficiently reduced glass particulate contamination and the evaluation methods used were appropriate for quantifying these levels of contamination.

Development of a LC–MS method for quantification of FK-3000 and its application to in vivo pharmacokinetic study in drug development

FK-3000 can inhibit proliferation of carcinomas and arrest the growth of carcinoma cells through cytotoxic (apoptosis induction) and cytostatic (cell cycle arrest) effects. A rapid and sensitive assay was developed and validated using liquid chromatography-mass spectrometry (LC-MS) for FK-3000 in rat plasma. FK-3000 was extracted with ethyl acetate from rat plasma samples, and the residue containing the FK-3000 was dried in a gentle stream of nitrogen and reconstituted with acetonitrile. The FK-3000 was quantified using high-performance liquid chromatography (HPLC; Waters Alliance 2695) with a reversed phase Gemini column (3 mm × 150 mm, 5 μm; Phenomenex, USA) and a Waters Micromass ZQ detector. FK-3000 and phenazine, an internal standard (IS), were analyzed by selected ion monitoring (SIM) at m/z transitions of 418.45 and 256, respectively. A lower limit of quantification (LLOQ) of 10 ng/mL was observed, with a linear dynamic range from 10 to 10,000 ng/mL (R>0.999). The accuracy, precision, recovery, matrix effects, and stability of the assay were deemed acceptable according to the FDA guidance for industry (bioanalytical method validation). The FK-3000 concentration was measured in plasma samples up to 6 h following FK-3000 administration at an oral dose of 20 mg/kg. The findings indicate that the assay method is suitable for routine pharmacokinetic (PK) studies of FK-3000 in rats.

Vitamin D Receptor-Mediated Upregulation of CYP3A4 and MDR1 by Quercetin in Caco-2 cells

To examine whether quercetin interacts with vitamin D receptor, we investigated the effects of quercetin on vitamin D receptor activity in human intestinal Caco-2 cells. The effects of quercetin on the expression of the vitamin D receptor target genes, vitamin D3 24-hydroxylase, cytochrome P450 3A4, multidrug resistance protein 1, and transient receptor potential vanilloid type 6 were measured using quantitative polymerase chain reaction. The vitamin D receptor siRNA was used to assess the involvement of the vitamin D receptor. Vitamin D receptor activation using a vitamin D responsive element-mediated cytochrome P450 3A4 reporter gene assay was investigated in Caco-2 cells transfected with human vitamin D receptor. We also studied the magnitude of the vitamin D receptor activation and/or synergism between 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3] and quercetin-like flavonoids. Slight but significant increases in the mRNA expression of cytochrome P450 3A4, vitamin D3 24-hydroxylase, multidrug resistance protein 1, and transient receptor potential vanilloid type 6 were observed after 3 days of continual quercetin treatment. The silencing effect of vitamin D receptor by vitamin D receptor siRNA in Caco-2 cells significantly attenuated the induction of the vitamin D receptor target genes. Moreover, quercetin significantly enhanced cytochrome P450 3A4 reporter activity in Caco-2 cells in a dose-dependent manner, and the expression of exogenous vitamin D receptor further stimulated the vitamin D receptor activity. Quercetin-like flavonoids such as kaempferol stimulated the vitamin D receptor activity in a manner similar to that seen with quercetin. Taken together, the data indicates that quercetin upregulates cytochrome P450 3A4 and multidrug resistance protein 1 expression in Caco-2 cells likely via a vitamin D receptor-dependent pathway.

Feasibility of the functional expression of the human organic anion transporting polypeptide 1B1 (OATP1B1) and its genetic variant 521T/C in the mouse liver

&NA; The objective of this study was to examine the feasibility of functional expression of the human organic anion transporting polypeptide 1B1 (hOATP1B1) forms in the liver of the mouse. After the mouse received the gene of interest (i.e., luciferase as the reporter or hOATP1B1) via hydrodynamic gene delivery (HGD) method, the expression was found to be liver‐specific while alterations in the serum biochemistry and hepatocyte histology were apparently transient and reversible. The reporter activity was also detected in the plasma, but not in the blood cell in mice that received HGD, suggesting that the protein is probably released due to transiently increased permeability in hepatocytes by HGD. Using this delivery condition, the expression of hOATP1B1 was readily detected in the liver, but not in other tissues, of the mice receiving HGD for the transporter gene. Compared with the sham control mice, the uptake of pravastatin into the liver increased significantly in mice receiving hOATP1B1 wild type; the uptake parameters decreased consistently in mice expressing the 521T>C variant compared with that of the wild type control. These observations suggest that the functional expression of human transporter gene in mice is feasible, further suggesting that this treatment is practically useful in the pharmacokinetic studies for hOATP1B1 substrates. Graphical abstract Figure. No caption available.

Gender differences in the hepatic elimination and pharmacokinetics of lobeglitazone in rats

The pharmacokinetics of lobeglitazone (LB) was studied after intravenous administration at a dose of 1 mg/kg and oral administration at doses of 0.1, 1 and 10 mg/kg in male and female rats. The area under the plasma concentration-time curve from time zero to infinity (AUCinf ) after intravenous administration was approximately 7.1 times higher in female rats than in male rats. In addition, the AUCinf in the case of oral administration was at least 4.4 times higher in female rats and appeared to increase in proportion to the dose in both genders. The in vitro half-lives were 18.8 ± 4.45 min and 60.7 ± 11.2 min, as evidenced by incubating liver microsomes obtained from male and female rats, respectively. As a result, the estimated CLint for LB for male rat liver microsomes (0.0779 ± 0.0233 ml/min/mg protein) was much higher than that for female rat liver microsomes (0.0233 ± 0.0039 ml/min/mg protein, p < 0.05). These observations suggest that there are gender differences in the pharmacokinetics and hepatic metabolism for LB in rats. Copyright

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

1. 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. 2. 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. 3. 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. 4. 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.

Model-based pharmacokinetic and pharmacodynamic analysis for acute effects of a small molecule inhibitor of diacylglycerol acyltransferase-1 in the TallyHo/JngJ polygenic mouse

Abstract The purpose of this study was to evaluate the acute effect of a small molecule inhibitor of DGAT-1 on triglycerides (TG) and cholesterol in polygenic type 2 diabetic TallyHo/JngJ (TH) mice. PF-04620110, a potent and selective DGAT-1 inhibitor, was used as a model compound in this study and which was administered to TH and ICR mice. The concentration of the model compound that produced 50% of maximum lowering of TG level (IC50) in TH mice was not significantly different from that in ICR mice, when estimated using the model-based pharmacokinetic and pharmacodynamic assay, a two-compartmental model and an indirect response model. The clearance of the inhibitor in TH mice was fivefold higher than that in ICR mice, suggesting significantly altered pharmacokinetics. Moreover, the in vitro metabolic elimination kinetic parameters (ke,met), determined using liver microsomes from TH and ICR mice were 1.24 ± 0.14 and 0.174 ± 0.116 min−1, respectively. Thus, we report that the differences in the acute effects of the small molecule DAGT-1 inhibitor between TH mice and ICR mice can be attributed to altered pharmacokinetics caused by an altered metabolic rate for the compound in TH mice.

Determination of Penicillium griseofulvum-oriented pyripyropene A, a selective inhibitor of acyl-coenzyme A:cholesterol acyltransferase 2, in mouse plasma using liquid chromatography-tandem mass spectrometry and its application to pharmacokinetic studies

In this study, we developed a method for the determination of Penicillium griseofulvum-oriented pyripyropene A (PPPA), a selective inhibitor of acyl-coenzyme A:cholesterol acyltransferase 2, in mouse and human plasma and validated it using liquid chromatography-tandem mass spectrometry. Pyripyropene A (PPPA) and an internal standard, carbamazepine, were separated using a Xterra MS C18 column with a mixture of acetonitrile and 0.1% formic acid as the mobile phase. The ion transitions monitored in positive-ion mode [M + H]+ of multiple-reaction monitoring (MRM) were m/z 148.0 from m/z 584.0 for PPPA and m/z 194.0 from m/z 237.0 for the internal standard. The detector response was specific and linear for PPPA at concentrations within the range from 1 to 5,000 ng/mL. The intra-/inter-day precision and accuracy of the method was acceptable by the criteria for assay validation. The matrix effects of PPPA ranged from 97.6 to 104.2% and from 93.3 to 105.3% in post-preparative mouse and human plasma samples, respectively. PPPA was also stable under various processing and/or handling conditions. Finally, PPPA concentrations in the mouse plasma samples could be measured after intravenous, intraperitoneal, or oral administration of PPPA, suggesting that the assay is useful for pharmacokinetic studies on mice and applicable to human studies.