Association of CXCL1 promoter polymorphism with ischaemic stroke in Korean population

This is a pilot study analysing association of chemokine gene polymorphisms (CXCL1, rs3117604; CXCL2, rs3806792; CCL2, rs2857656 and rs3760396; CCL5, rs2107538) in Korean patients with ischemic stroke (IS) (n = 120) and age-matched controls (n = 267). The CXCL1 gene and particularly T allele of rs3117604 was associated with IS.

Simultaneous Determination of Levocetirizine and Pseudoephedrine in Dog Plasma by Liquid Chromatography-Mass Spectrometry in the Presence of Dextrocetirizine

Purpose. This study describes the development of a rapid and sensitive LC-ESI-MS assay for simultaneous enantioselective determination of levocetirizine and pseudoephedrine in dog plasma in the presence of dextrocetirizine. Methods. Separations were achieved on an Ultron ES-OVM chiral column using the mobile phase consisting of 10 mM aqueous NH4OAc (pH 6.6) and acetonitrile (9:1 v/v). Results. The retention times of pseudoephedrine, dextrocetirizine, levocetirizine and diazepam (internal standard) were 5.2, 8.3, 9.6 and 11.6 min, respectively, and the total run time was less than 15 min. The assay was validated to demonstrate the linearity, accuracy and precision, recovery and stability. The calibration curves were linear over the concentration range from 1 – 200 ng/mL for levocetirizine and from 5 – 1000 ng/mL for pseudoephedrine. Conclusions. The developed assay was successfully applied to a pharmacokinetic study after oral administration of the racemic cetirizine (0.5 mg/kg, or 0.25 mg/kg as levocetirizine) and pseudoephedrine (12 mg/kg) in the dog. This article is open to POST-PUBLICATION REVIEW. Registered readers (see “For Readers”) may comment by clicking on ABSTRACT on the issue’s contents page.

Simultaneous determination of fimasartan, a novel antihypertensive agent, and its active metabolite in rat plasma by liquid chromatography-tandem mass spectrometry

Fimasartan, 2-butyl-5-dimethylaminothiocarbonylmethyl-6-methyl-3-[[2'-(1H tetrazol -5-yl)biphenyl-4-yl]methyl]pyrimidin-4(3H)-one (BR-A-657), is a novel angiotensin II receptor blocker exhibiting potent and selective AT1 receptor blocking activity. This study reports the liquid chromatography-tandem mass spectrometry assay for the simultaneous determination of fimasartan and its active metabolite, BR-A-557, in rat plasma. The assay was validated to demonstrate the specificity, linearity, recovery, lower limit of quantification, accuracy, precision and stability. The multiple reaction monitoring was based on the transition of m/z 502.1 → 207.1 for fimasartan, 486.2 → 207.1 for BR-A-557 and 526.1 → 207.1 for BR-A-563 (internal standard). The assay utilized a simple precipitation procedure with acetonitrile and isocratic elution. The LLOQ was 0.2 ng/mL for fimasartan and BR-A-557 using 50 μL plasma samples. The assay was linear over a concentration range from 0.2 to 500 ng/mL for fimasartan and BR-A-557, with correlation coefficients >0.9995. The intra- and inter-day assay accuracies were 93.6-108.0 and 90.8-101.4% for fimasartan and 102.2-107.1 and 99.6-103.3% for BR-A-557, respectively. The intra- and inter-day precision were 2.4-4.4 and 3.0-13.4% for fimasartan and 3.1-5.2 and 2.8-9.8% for BR-A-557, respectively. The developed assay may be used to study the metabolism and mechanistic pharmacokinetics of fimasartan in future studies.

Prediction of human pharmacokinetics and tissue distribution of apicidin, a potent histone deacetylase inhibitor, by physiologically based pharmacokinetic modeling

PURPOSE

The objectives of this study were to develop physiologically based models for the pharmacokinetics (PK) and organ distribution of apicidin in rats and mice and to predict human PK in blood and organs.

METHODS

The PK of apicidin was characterized in rats and mice after i.v. bolus injection, and distribution to various tissues was determined in rats following i.v. infusions at steady state. The developed models were prospectively validated within rat and within mouse and by scaling from rat to mouse using data after multiple i.v. injections. Human PK was predicted by the physiologically based modeling using intrinsic clearance data for humans from in vitro experiments.

RESULTS

The Cl(s) predicted for human (9.8 ml/min/kg) was lower than those found in mice (116.9 ml/min/kg) and rats (61.6 ml/min/kg), and the V(ss) predicted for human (1.9 l/kg) was less than in mice (2.0 l/kg) and rats (2.5 l/kg). Consequently, the predicted t (1/2) was longer in human (2.3 h) than in mice and rats (0.4 and 0.9 h, respectively). The highest concentrations of apicidin were predicted in liver followed by adipose tissue, kidney, lung, spleen, heart, arterial blood, venous blood, small intestine, stomach, muscle, testis, and brain.

CONCLUSIONS

The developed models adequately described the PK of apicidin in rats and mice and were applied to predict human PK. These models may be useful in predicting human blood and tissue concentrations of apicidin under different exposure conditions.

Assessment of bisphenol A exposure in Korean pregnant women by physiologically based pharmacokinetic modeling

The objective of this study was to predict the exposure to bisphenol A (BPA) after oral intake in human blood and tissues using physiologically based pharmacokinetic (PBPK) modeling. A refined PBPK model was developed taking into account of glucuronidation, biliary excretion, and slow absorption of BPA in order to describe the second peak of BPA observed following oral intake. This developed model adequately described the second peak and BPA concentrations in blood and various tissues in rats after oral administration. A prospective validation study in rats additionally supported the proposed model. For extrapolation to humans, a daily oral BPA dose of 0.237 mg/70 kg/d or 0.0034 mg/kg/d was predicted to achieve an average steady-state blood concentration of 0.0055 ng/ml (median blood BPA concentration in Korean pregnant women). This dose was lower than the reference dose (RfD, 0.016 mg/kg/d) and the tolerable daily intake established by the European Commission (10 μg/kg/d). Data indicate that enterohepatic recirculation may be toxicologically important as this pathway may increase exposure and terminal half-life of BPA in humans.

Determination of zearalenone by liquid chromatography/tandem mass spectrometry and application to a pharmacokinetic study

Zearalenone, a mycotoxin biosynthesized by various Fusarium fungi, is widely found as a contaminant in grains and animal feeds. This study describes a rapid and sensitive LC/MS/MS assay method for the quantification of zearalenone in rat serum. The assay was validated to demonstrate the specificity, linearity, recovery, lower limit of quantification (LLOQ), accuracy and precision. The multiple reaction monitoring was based on the transition of m/z 317.0 --> 130.9 for zearalenone and 319.0 --> 204.8 for zearalanone (internal standard). The assay utilized a single liquid-liquid extraction with t-butyl methyl ether and isocratic elution, and the LLOQ was 0.5 ng/mL using 0.1 mL rat serum. The assay was linear over a concentration range from 0.5 to 200 ng/mL, with correlation coefficients >0.9996. The mean intra- and inter-day assay accuracy was 101.2-112.9 and 96.3-108.0%, respectively. The mean intra- and inter-day precision was between 1.3-7.6 and 3.6-10.6%, respectively. The developed assay was applied to a pharmacokinetic study after a bolus intravenous injection of zearalenone in rats.

Interspecies scaling of oleanolic acid in mice, rats, rabbits and dogs and prediction of human pharmacokinetics

This study was conducted to predict the pharmacokinetics of oleanolic acid in humans based on animal data by allometry and several species-invariant time methods. Oleanolic acid was injected intravenously to mice, rats, rabbit and dogs (dose 1 mg/kg). The serum concentration-time profiles of oleanolic acid were best described by bi-exponential equation in all animal species. The average Cl, V ( ss ) and t ( 1/2 ) were 0.065 L/h, 0.019 L and 28.7 min in mice, 0.47 +/- 0.06 L/h, 0.117 +/- 0.029 L and 29.7 +/- 12.2 min in rats, 2.77 +/- 0.88 L/h, 1.83 +/- 0.60 L and 84.4 +/- 16.9 min in rabbits and 14.0 +/- 0.7 L/h, 9.2 +/- 10.1 L and 54.5 +/- 57.2 min in dogs, respectively. Based on animal data, human pharmacokinetic parameters of Cl, V ( ss ) and t (1/2) were predicted by simple allometry. In addition, actual concentration-time profiles obtained from animals were transformed to human profiles by species-invariant times of kallynochron, apolysichron and dienetichron. The predicted human pharmacokinetic parameters of Cl, V ( ss ) and t (1/2) by using simple allometry and species-invariant time transformation method ranged from 48.3-97.2 L/h, 49.1-92.9 L and 45.6-187.2 min, respectively. Those predicted parameters of oleanolic acid may be useful in designing dosing schedules of oleanolic acid in future clinical studies.

Disposition, oral bioavailability, and tissue distribution of zearalenone in rats at various dose levels

This study was conducted to characterize the disposition, oral bioavailability, and tissue distribution of zearalenone in rats. The pharmacokinetics and tissue distribution of zearalenone were studied after intravenous (i.v.) or oral (p.o.) administration at doses ranging from 1 to 8 mg/kg in intact and bile duct-cannulated rats. Serum, bile, and urine concentrations were determined by liquid chromatography and mass spectroscopy (LC/MS/MS) and tissue concentrations by high-performance liquid chromatography (HPLC)/fluorescence detection assays. Noncompartmental methods were used for pharmacokinetic analysis. Average Cl(s) (range 5.0-6.6 L/h/kg) and V(dss) (range 2-4.7 L/kg) remained unaltered over an i.v. dose range from 1 to 8 mg/kg, and area under the concentration-time curve (AUC) and initial peak concentrations increased linearly with dose. Minimal quantities of zearalenone were excreted unchanged in urine (f(e,urine) 0.5 +/- 0.2%) and bile (f(e,bile) 0.91 +/- 0.64%). After p.o. administration of 8 mg/kg, zearalenone was rapidly absorbed and serum concentration-time profiles showed a distinct second peak. The absolute oral bioavailability was low (2.7%). Comparing bile duct-cannulated to intact rats at a dose of 8 mg/kg, the impact of biliary excretion on overall pharmacokinetics was more pronounced after p.o. than after i.v. administration. Upon i.v. infusion to steady state, the highest zearalenone concentration was found in small intestine, followed by kidneys, liver, adipose tissue, and lung. Zearalenone concentrations in stomach, heart, brain, spleen, muscle, and testes were lower than those found in serum. The pharmacokinetics and tissue distribution data from this study may be useful to develop physiologically based pharmacokinetic (PBPK) models for zearalenone and subsequently to predict the pharmacokinetics and toxicity in humans.

Physiologically based pharmacokinetics of zearalenone

The objectives of this study were to (1) develop physiologically based pharmacokinetic (PBPK) models for zearalenone following intravenous (i.v.) and oral (p.o.) dosing in rats and (2) predict concentrations in humans via interspecies scaling. The model for i.v. dosing consisted of vein, artery, lung, liver, spleen, kidneys, heart, testes, brain, muscle, adipose tissue, stomach, and small intestine. To describe the secondary peak phenomenon observed after p.o. administration, the absorption model was constructed to reflect glucuronidation, biliary excretion, enterohepatic recirculation, and fast and slow absorption processes from the lumenal compartment. The developed models adequately described observed concentration-time data in rats after i.v. or p.o. administration. Upon model validation in rats, steady-state zearalenone concentrations in blood and tissues were simulated for rats after once daily p.o. exposures (0.1 mg/kg/d). The average steady-state blood zearalenone concentration predicted in rat was 0.014 ng/ml. Subsequently, a daily human p.o. dose needed to achieve the same steady-state blood concentration found in rats (0.014 ng/ml) was determined to be 0.0312 mg/kg/d or 2.18 mg/70 kg/d. The steady-state zearalenone concentration-time profiles in blood and tissues were also simulated for human after multiple p.o. administrations (dose 0.0312 mg/kg/d). The developed PBPK models adequately described the pharmacokinetics in rats and may be useful in predicting human blood and tissue concentrations for zearalenone under different p,o, exposure conditions.

Pretreatment effects of moxibustion on the skin permeation of FITC-dextran

This study was conducted to evaluate the pretreatment effects of different in vivo moxibustion on the permeation of a model high molecular compound, FITC-dextran, with a mean molecular weight of 4 kDa (FD-4), through excised hairless rat skin. Direct or indirect moxibustion (0.10 g moxa) was pretreated consecutively 4 times every 5 min on the abdomen of hairless rats, and the permeation of FD-4 was determined through the excised skin over 8h from 30 min after starting the first moxibustion. This consecutive moxibustion pretreatment showed a significant increase in the skin temperature as well as skin permeation of FD-4 compared with the control group (no moxibustion pretreatment). Quantitative parameters showed an increase in skin temperature and skin permeation: the area under the skin temperature over control temperature-time curve during one burning cycle (5.0 min) (AUCtemp) or the maximum skin temperature during moxibustion (Tmax) and the cumulative amount of FD-4 permeated through skin over 8h (Q8) or steady-state flux were increased by moxibustion pretreatment. Then, the effect of pedestal thickness (distance from the moxa cylinder and skin surface), shape of the moxa cylinder (5mm diameter, 13 mm height or 9 mm diameter, 7 mm height), burning materials (moxa or aromatic incense), pedestal component (paper, potato or ginger) and moxibustion pretreatment method (direct or indirect moxibustion) was evaluated on the AUCtemp or Tmax and Q8 or flux. The amount of protein leached from the skin surface was also determined as an inflammatory index by this moxibustion pretreatment. When the skin temperature was increased to 60 degrees C, the Q8 or flux as well as the amount of protein leached were markedly increased. When the skin temperature was controlled to 42 to 45 degrees C by an adequate selection of pedestal thickness, shape of the moxa cylinder, burning materials, pedestal component and moxibustion pretreatment method, on the other hand, protein leaching remained unaltered, but the Q8 or flux significantly increased with the Tmax. This study thus provides credible evidence that moxibustion pretreatment increases the skin permeation of high molecular compounds.

Pharmacokinetics of GST-TatdMt, a recombinant fusion protein possessing potent anti-obesity activity, in mice

This study examined the absorption and pharmacokinetic disposition of 125I-GST-TatdMt, a recombinant Tat protein possessing potent anti-obesity activity, in mice after vascular and extravascular administration. GST-TatdMt was over-expressed in E. coli, purified, and radioiodinated using the IODO-GEN method. 125I-GST-TatdMt was administered to mice by i.v., i.p. and oral administration at doses of 652.7 nCi (102.3 microg). Upon i.v. injection, the average terminal elimination half-life (t1/2,lambdaz), AUC and AUMC were 6.4 h, 318.2 nCixh/mL and 2518 nCixh2/ mL, respectively. The highest radioactivity was observed in lung followed by liver, spleen, heart and kidney. The t1/2lambdaz values obtained from i.v., i.p., and oral administration were comparable from each other (range 5.8-6.4 h). The absolute bioavailability of 125I-GST-TatdMt was 42.8% and 60.5% after p.o. and i.p. administration, respectively. Given the cell-penetrating nature, 125I-GST-TatdMt may be absorbed into the systemic circulation to a relatively high extent after extravascular administration.