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ABSTRACT: A sensitive and simple detection method coupling ultra-performance liquid chromatography with tandem mass spectrometry was developed and validated to analyze sumatriptan levels in human plasma. The plasma sample preparations for the analysis were based on liquid-liquid extraction with ethyl acetate, evaporation, and reconstitution. MS/MS detection was performed on a triple-quadrupole tandem mass spectrometer by monitoring the protonated parent→daughter ion pairs at m/z 296→58 and m/z 388→71 for sumatriptan and terazosin (internal standard), respectively. The method was validated with respect to its specificity, linearity, sensitivity, accuracy, precision, recovery, and stability. The calibration curve was linear from 0.5 to 50ng/mL (r>0.999). The mean extraction recovery for sumatriptan was higher than 62.3%. The method accuracy was within 97.4%, and the relative standard deviation of the intra- and inter-day precision values was within 11.7% at all quality control levels. Plasma samples that contained sumatriptan were stable under three freeze-thaw cycles, short- and long-term storage, and autosampler conditions. This method was successfully applied to a pharmacokinetic study conducted with 10 healthy volunteers. After oral administration of 50-mg sumatriptan and serial blood sampling over 12h, the mean area under the plasma concentration-time curve from time 0 to 12h and the maximum plasma concentration were 116.2ngh/mL and 33.2ng/mL, respectively.
Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 03/2013; 919-920:38-42. · 2.78 Impact Factor
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ABSTRACT: Drug-induced torsades de pointes (TdP), a life-threatening arrhythmia associated with prolongation of the QT interval, has been a significant reason for withdrawal of several medicines from the market. Prolongation of the QT interval is considered as the best biomarker for predicting the torsadogenic risk of a new chemical entity. Because of the difficulty assessing the risk for TdP during drug development, we evaluated the metabolic phenotype for predicting QT prolongation induced by sparfloxacin, and elucidated the metabolic pathway related to the QT prolongation. We performed electrocardiography analysis and liquid chromatography-mass spectroscopy-based metabolic profiling of plasma samples obtained from 15 guinea pigs after administration of sparfloxacin at doses of 33.3, 100, and 300 mg/kg. Principal component analysis and partial least squares modelling were conducted to select the metabolites that substantially contributed to the prediction of QT prolongation. QTc increased significantly with increasing dose (r = 0.93). From the PLS analysis, the key metabolites that showed the highest variable importance in the projection values (>1.5) were selected, identified, and used to determine the metabolic network. In particular, cytidine-5'-diphosphate (CDP), deoxycorticosterone, L-aspartic acid and stearic acid were found to be final metabolomic phenotypes for the prediction of QT prolongation. Metabolomic phenotypes for predicting drug-induced QT prolongation of sparfloxacin were developed and can be applied to cardiac toxicity screening of other drugs. In addition, this integrative pharmacometabolomic approach would serve as a good tool for predicting pharmacodynamic or toxicological effects caused by changes in dose.
PLoS ONE 01/2013; 8(4):e60556. · 4.09 Impact Factor
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ABSTRACT: The aim of this study was to investigate the pharmacokinetics and dose proportionality of a single, intravenous dose of pazufloxacin mesilate, an injectable fluoroquinolone antibiotic, in healthy Korean male volunteers.
In this open-label, four-dose, parallel study, subjects were randomized to receive a single dose of pazufloxacin mesilate 300, 500, 600, and 1,000 mg (n = 6, 20, 6, and 8, respectively) administered as a 1-h intravenous infusion. Blood and urine samples were collected serially from 0 to 24 h after drug administration and analyzed using a validated HPLC method. Tolerability was assessed by monitoring clinical laboratory parameters and adverse events.
After single-dose intravenous administration of pazufloxacin mesilate, the mean C(max) for groups treated with 300, 500, 600, and 1,000 mg doses ranged from 5.11 to 18.06 μg/mL; the mean AUC(0-t) ranged from 13.70 to 58.60 μg × h/mL. Pazufloxacin exhibits Lack of dose proportionality was concluded over the dose range of 300 - 1,000 mg, based on linear regression model and power model . At all four dosages studied, pazufloxacin mesilate was well tolerated.
Our data suggest that all regimens of pazufloxacin administration were well tolerated. Pazufloxacin exhibits lack of dose proportionality over the dose range of 300 - 1,000 mg.
Expert Opinion on Drug Metabolism & Toxicology 08/2012; 8(8):921-8. · 3.12 Impact Factor
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ABSTRACT: The effect of bio-geochemical processes on speciation, fate, and transport of arsenic was investigated through the laboratory
tests. Shewanella sp., iron-reducing bacteria, was used for batch and column tests. In contrast to the control batch test, the bio-active batch
test indicated that Shewanella sp. reduced As(V) to As(III) with concurrent oxidation of lactate to acetate and the decrease of Eh. As time went, a significant
amount of the precipitates were formed, and the removal of arsenic species from the solution was attributed to precipitates.
SEM-EDX and chemical analyses of the precipitates suggested that As(III) and As(V) were precipitated with sulfides. The reduction
and subsequent precipitation of arsenic species were also observed in the column tests. The batch and column tests suggest
that in natural groundwater system, Shewanella sp. participates in the reduction of As(V) and sulfate, and sulfides produced by the microbial activity precipitate As(V)
and As(III).
Geosciences Journal 04/2012; 12(2):151-157. · 0.74 Impact Factor
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ABSTRACT: Levofloxacin and cyclosporine show different pharmacokinetic properties, but are known to be dose proportional within the therapeutic range. The authors evaluated the pharmacokinetic proportionality of levofloxacin and cyclosporine over a 100-fold dose range in healthy human volunteers, by liquid chromatography-tandem mass spectrometry (LC-MS/MS).
Two independent, randomized, crossover studies were performed. For levofloxacin, eight volunteers were randomly assigned in a 1:1 ratio to receive a low dose (7.5 mg) orally or intravenously, followed by a 1-week washout period and administration via the alternate route. After another 1-week washout period, a therapeutic dose (750 mg) was administered to all eight subjects. For cyclosporine, another eight volunteers received a low dose (2 mg) or a therapeutic dose (200 mg) orally with a 1-week washout period. Drug concentrations were determined by LC-MS/MS.
For levofloxacin, the mean values for dose-normalized C(max) and AUC(last) with the two doses were as follows: therapeutic dose, 15.2 ± 4.6 ng/ml/mg and 103.6 ± 15.5 ng·h/ml/mg, respectively; low dose, 17.1 ± 6.5 ng/ml/mg and 72.6 ± 8.7 ng·h/ml/mg, respectively. For cyclosporine, the mean values for dose-normalized C(max) and AUC(last) were as follows: therapeutic dose, 4.9 ± 1.5 ng/ml/mg and 15.4 ± 4.9 ng·h/ml/mg, respectively; low dose, 1.6 ± 0.6 ng/ml/mg and 9.3 ± 7.3 ng·h/ml/mg, respectively.
In this study levofloxacin, which is completely absorbed and primarily eliminated renally without modification, showed better pharmacokinetic proportionality than cyclosporine, which is poorly absorbed and extensively metabolized.
Expert Opinion on Drug Metabolism & Toxicology 03/2012; 8(4):399-405. · 3.12 Impact Factor
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ABSTRACT: In metabolomic research, it is important to reduce systematic error in experimental conditions. To ensure that metabolomic data from different studies are comparable, it is necessary to remove unwanted systematic factors by data normalization. Several normalization methods are used for metabolomic data, but the best method has not yet been identified. In this study, to reduce variation from non-biological systematic errors, we applied 1-norm, 2-norm, and quantile normalization methods to liquid chromatography-mass spectrometry (LC-MS)-based metabolomic data from human urine samples after oral administration of cyclosporine (high- and low-dose) in healthy volunteers and compared the effectiveness of the three methods. The principal component analysis (PCA) score plot showed more obvious groupings according to the cyclosporine dose after quantile normalization than after the other two methods and prior to normalization. Quantile normalization is a simple and effective method to reduce non-biological systematic variation from human LC-MS-based metabolomic data, revealing the biological variance.
Analytical Sciences 01/2012; 28(8):801-5. · 1.25 Impact Factor
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ABSTRACT: Bo-yang-hwan-o-tang (BHT) is an oriental herbal medicine for treating brain disorders such as cerebral ischemia. The objective of this study was to develop an economically feasible and time-saving high-throughput screening method to monitor the potential inhibitory effects of BHT on human cytochrome P450 (CYP) enzymes in vitro. Two cocktail sets were used for incubation of human liver microsomes: Cocktail A: 6 probe substrates for CYP1A2, CYP2A6, CYP2C8, CYP2C19, CYP2D6, CYP3A4; Cocktail B: 3 for CYP2B6, CYP2C9, CYP2E1. The concentrations of the substrate metabolites were simultaneously analyzed using UPLC/MS/MS. The BHT extract had almost negligible inhibitory effects on the nine human CYP isoforms tested, with the half-maximal inhibitory concentration value ranged from 3624.99 to 45412.44 μg/ml. The results suggest that BHT extract has no inhibitory effects on CYP isoforms within the clinically recommended dosage range. We conclude that BHT might be free of drug-herb interactions when co-administered with other medicines. However, more in vivo human studies are needed to confirm these results. The high-throughput screening method can be a useful tool for drug discovery and for understanding drug interactions.
Analytical Sciences 01/2012; 28(12):1197-201. · 1.25 Impact Factor
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ABSTRACT: A new controlled-release formulation of aceclofenac 200 mg (Clanza CR®) developed by Korea United Pharm., Inc., South Korea, for once-daily (od) dosing provides biphasic aceclofenac release consisting of immediate release of 85 mg followed by sustained release of 115 mg. Food has been known to affect the rate and extent of absorption of several drugs, in both immediate-release and controlled-release formulations.
The aim of this study was to evaluate the relative bioavailability of a new controlled-release formulation of aceclofenac (200 mg od; Clanza CR®) in comparison with immediate-release aceclofenac (100 mg twice daily [bid], Airtal®) and to assess the effect of food on the pharmacokinetics of the new controlled-release aceclofenac formulation.
This study was designed as a randomized, open-label, three treatment-period, crossover, single-centre study with a 1-week washout in 41 healthy adults. The three treatments consisted of immediate-release aceclofenac 100 mg bid administered under fasting conditions; controlled-release aceclofenac 200 mg od administered under fasting conditions; and controlled-release aceclofenac 200 mg od administered immediately after a standardized high-fat breakfast. Plasma concentrations of aceclofenac were determined using a high-performance liquid chromatography method.
In the fasted state, the 90% confidence intervals (CIs) of the least squares geometric mean ratios (GMRs) for the area under the plasma concentration-time curve from time zero to 24 hours (AUC(24)) and the peak plasma concentration (C(max)) of aceclofenac for the controlled-release and immediate-release formulations of aceclofenac were all within the bioequivalence criteria range of 0.8-1.25. The 90% CIs of the GMRs for the AUC(24) and C(max) of aceclofenac for the controlled-release formulation of aceclofenac in the fed and fasted states were also within the bioequivalence range. Both aceclofenac formulations were well tolerated in all subjects, and no serious adverse effects were observed.
The results demonstrate that controlled-release aceclofenac 200 mg is equivalent to immediate-release aceclofenac 100 mg when administered at the same total daily dose. Additionally, the bioavailability of controlled-release aceclofenac was not affected by high-fat foods.
Clinical Drug Investigation 12/2011; 32(2):111-9. · 1.82 Impact Factor
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ABSTRACT: An enteric-coated formulation of triflusal (triflusal EC), an antiplatelet agent, was developed to reduce the high incidence of gastrointestinal adverse events (AEs). The aim of this study is to compare the pharmacokinetics, pharmacodynamics and safety of triflusal EC with triflusal in healthy Korean male subjects to determine bioequivalence and non-inferiority for the purposes of marketing approval.
A randomized, open-label, two-period, crossover study was conducted in 38 subjects. Either triflusal EC or triflusal was administered orally as a single 900 mg loading dose (day 1) followed by eight 600 mg/day maintenance doses on days 2 - 9, with a 13-day washout period. The plasma concentrations of 2-hydroxy-4-trifluoromethyl benzoic acid (HTB), the predominant active metabolite of triflusal, were assessed after administration of the loading dose, using HPLC/MS/MS. The platelet aggregation response to arachidonic acid was determined using turbidimetric aggregometry.
The 90% CIs, for the geometric mean ratios of the log-transformed AUC(τ) and C(max) of HTB were seen to be within the predetermined range of 0.8 - 1.25. Triflusal EC was also shown to be non-inferior in its anti-aggregatory effect. No serious AEs were reported during this study.
The pharmacokinetic and pharmacodynamic profiles of the two triflusal formulations met the requirements for bioequivalence and non-inferiority, respectively. Both formulations were well tolerated.
Expert Opinion on Drug Metabolism & Toxicology 12/2011; 7(12):1471-9. · 3.12 Impact Factor
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ABSTRACT: The aim of this study was to compare the pharmacokinetics (PK) and safety of fimasartan (BR-A-657), an angiotensin II receptor antagonist, between healthy young (19 - 45 years) and older (≥ 65 years) male subjects.
To assess the effect of age on PK and safety, fimasartan was administered as a single 240 mg tablet to 12 young and 10 older male subjects, followed by serial blood sampling over 48 h. Plasma concentrations of fimasartan were analyzed using validated HPLC-MS/MS. Clinical and laboratory adverse events were assessed.
After oral administration of 240 mg fimasartan, the mean area under the plasma concentration-time curve from time zero to infinity (AUC(0→∞)) was 2899.0 ng/ml/h in the older, which was significantly greater than in young subjects (1767.4 ng/ml/h; p = 0.03). The geometric mean AUC(0→∞) was 69.4% higher in older than in young subjects. The maximum plasma concentration (C(max)), time to reach C(max) and elimination half-life for fimasartan did not differ significantly between the older and young groups. Importantly, fimasartan was well tolerated during this study.
While some PK parameters were statistically different between the two groups, the effect of age on the PK was modest (e.g., AUC increase < twofold in older subjects).
Expert Opinion on Drug Metabolism & Toxicology 09/2011; 7(11):1337-44. · 3.12 Impact Factor
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ABSTRACT: Population pharmacokinetic (PK) and pharmacodynamic (PD) modeling of clopidogrel was developed from pooled data from healthy volunteers (n = 44) and stroke patients (n = 35). The PK modeling used plasma concentrations of the clopidogrel metabolite (SR26334), and the PD modeling used platelet aggregation. The models were developed using NONMEM and evaluated via visual predictive check (VPC). Data were analyzed by 2-compartment modeling with Erlang's absorption and first-order elimination. There was no statistically significant covariate for each model parameter. The typical point estimates of PK were k(tr) (identical transfer rate constant) = 5.97 h(-1), k(e) (elimination rate constant) = 0.126 h(-1), k(d) (distribution rate constant) = 0.212 h(-1), V(2) (volume of central compartment) = 21.0 L, and V(3) (volume of peripheral compartment) = 38.8 L. The typical point estimates of PD were k(in) (input rate) = 27.9 h(-1), E(max) (maximum effect on input rate) = 0.292 h(-1), EC(5) (0) (median effective concentration) = 0.00629 ng/mL, and BASE (predose aggregation) = 66.7%. The final model was used to estimate individual parameters using patient data and showed good predictions using VPC.
The Journal of Clinical Pharmacology 05/2011; 52(7):985-95. · 2.91 Impact Factor
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ABSTRACT: HMC05, a formulation containing eight different herbal extracts, has been used widely for several thousand years in China, Japan, and Korea as a remedy for hypertension and headache. Although its anti-inflammatory effects in mouse monocytic cell lines and anti-atherosclerotic effects in apoE-knockout mice have been reported, the pharmacodynamic effects of HMC05 in human subjects have not yet been investigated. We evaluated the efficacy and tolerability of this drug in 14 healthy male Korean subjects with normal or high-normal blood pressure (BP) in a randomized, single-blind, crossover study with a 2-week washout period. Four 500-mg tablets of HMC05 or placebo were orally administered three times daily to nine subjects with normal BP and five subjects with high-normal BP for 4 weeks. To assess the pharmacodynamic effects of HMC05, levels of high-sensitivity C-reactive protein and homocysteine, BP, and flow-mediated vasodilation were measured before and after the 4-week medication period with evaluation of tolerability. All 14 subjects completed the study, and HMC05 was well tolerated with no significant adverse events. HMC05 did not exhibit a significant BP-lowering effect in either BP group, and there were no significant differences in other pharmacodynamic values after HMC05 or placebo administration in the two groups. Further study is needed to evaluate the efficacy and tolerability of HMC05 in an adequate number of patients with hypertension.
Planta Medica 02/2011; 77(3):221-5. · 2.15 Impact Factor
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Jinwook Choi,
Jin Wook Kim,
Jeong-Wook Seo,
Chun Kee Chung,
Kyung-Hwan Kim,
Ju Han Kim,
Jong Hyo Kim,
Eui Kyu Chie,
Hyun-Jai Cho,
Jin Mo Goo, [......],
Won Ryang Wee,
Sang Mo Nam, Mi-Sun Lim,
Young-Ah Kim,
Seung Hoon Yang,
Eun Mi Jo,
Min-A Hwang,
Wan Suk Kim,
Eun Hye Lee,
Su Hi Choi
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ABSTRACT: Adoption of hospital information systems offers distinctive advantages in healthcare delivery. First, implementation of consolidated hospital information system in Seoul National University Hospital led to significant improvements in quality of healthcare and efficiency of hospital management.
THE HOSPITAL INFORMATION SYSTEM IN SEOUL NATIONAL UNIVERSITY HOSPITAL CONSISTS OF COMPONENT APPLICATIONS: clinical information systems, clinical research support systems, administrative information systems, management information systems, education support systems, and referral systems that operate to generate utmost performance when delivering healthcare services.
Clinical information systems, which consist of such applications as electronic medical records, picture archiving and communication systems, primarily support clinical activities. Clinical research support system provides valuable resources supporting various aspects of clinical activities, ranging from management of clinical laboratory tests to establishing care-giving procedures.
Seoul National University Hospital strives to move its hospital information system to a whole new level, which enables customized healthcare service and fulfills individual requirements. The current information strategy is being formulated as an initial step of development, promoting the establishment of next-generation hospital information system.
Healthcare informatics research. 12/2010; 16(4):299-304.
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ABSTRACT: An improved method for determining levels of levosulpiride in human plasma using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was developed and validated. The protein precipitation method was used for plasma sample preparation. Levosulpiride and an internal standard (IS) were isocratically separated on a UPLC BEH C(18) column with a mobile phase of ammonium formate buffer (1mM, adjusted to pH 3 with formic acid) and acetonitrile (60:40, v/v). MS/MS detection was performed by monitoring the parent-->daughter pair of levosulpiride and the IS at m/z 342-->112 and 329-->256, respectively. The method was linear from 2.5 to 200ng/mL and exhibited acceptable precision and percent recovery. The method was successfully demonstrated in pharmacokinetic and bioequivalence studies of two levosulpiride oral formulations administered to healthy volunteers. When compared to the previous LC-MS methods, the proposed method is faster, well-validated, and uses lesser plasma volume and a similar sensitivity. The use of UPLC allowed rapid and sensitive quantification of levosulpiride, making this method suitable for high-throughput clinical applications.
Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 08/2010; 878(24):2280-5. · 2.78 Impact Factor
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ABSTRACT: A rapid, specific, and sensitive method utilizing reversed-phase ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) was developed and validated to determine finasteride levels in human plasma. The plasma samples were prepared by liquid-liquid extraction with ethyl acetate, evaporation, and reconstitution. MS/MS analyses were performed on a triple-quadrupole tandem mass spectrometer by monitoring protonated parent-->daughter ion pairs at m/z 373-->305 for finasteride and m/z 237-->194 for carbamazepine (internal standard, IS). The method was validated with respect to linearity, recovery, specificity, accuracy, precision, and stability. The method exhibited a linear response from 0.1 to 30 ng/mL (r(2)>0.998). The limit of quantitation for finasteride in plasma was 0.1 ng/mL. The relative standard deviation (RSD) of intra- and inter-day measurements was less than 15% and the method was accurate within -6.0% to 2.31% at all quality-control levels. The mean extraction recovery was higher than 83% for finasteride and 84% for the IS. Plasma samples containing finasteride were stable under the three sets of conditions tested and the processed samples were stable up to 29 h in an autosampler at 5 degrees C. Detection and quantitation of both analytes within 3 min make this method suitable for high-throughput analyses. The method was successfully applied to a pharmacokinetic study of finasteride in healthy volunteers following oral administration.
Journal of chromatography. B, Analytical technologies in the biomedical and life sciences 06/2010; 878(20):1718-23. · 2.78 Impact Factor
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ABSTRACT: Heat shock proteins (HSPs) restore immature proteins or denatured proteins, thus protecting cells. Also, the expression of some HSPs is elevated substantially in malignant tumors, but the expression of HSPs in association with melanoma has yet to be studied. Therefore, we examined the expression patterns of HSP 70 and 105 in melanoma, benign melanocytic nevi and normal human skin.
Two specimens of malignant melanoma, two of benign melanocytic nevi and six of normal human skin were analyzed using Western blot analysis for expression of HSP 70 and 105. In another set, 16 specimens of malignant melanoma, 24 of benign melanocytic nevi and eight of normal human skin were analyzed for the expression of HSP 105 using immunohistochemical studies.
The Western blot analysis showed that HSP 70 was overexpressed in all three types. But, the HSP 105 was hardly expressed in normal human skin and benign melanocytic nevi. However, in malignant melanoma, the HSP 105 was overexpressed, and immunohistochemical examination of HSP 105 showed a result similar to that of Western blot analysis.
In our study, HSP 105 is thought to be a more relevant tumor-associated antigen in malignant melanoma than is HSP 70.
Journal of Cutaneous Pathology 06/2009; 36(5):511-6. · 1.56 Impact Factor
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ABSTRACT: A mathematical model was developed for describing the transport of arsenic, coupled with microbially-mediated biogeochemical processes. The biogeochemical characteristics of arsenic reactive transport processes were investigated in both batch and column tests, which showed that As(V) was reduced to As(III) by Shewanella sp., with the reduced arsenic species subsequently removed by precipitation. The breakthrough data obtained from the column experiments were used for the calibration of the arsenic reactive transport model. The reactive transport model, which only incorporated microbial reduction processes, showed a large discrepancy in predicting the observed As(III) concentration profiles, particularly later in the experiments. However, the model matched the experimental data much better with the inclusion of a term describing the precipitation process. Our results indicated that the precipitation reaction can be a major sink during microbially-mediated arsenic reactive transport. The proposed model provides a useful framework for predicting the transport of arsenic in saturated groundwater aquifers.
Water Research 05/2007; 41(10):2079-88. · 4.86 Impact Factor
