• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1684-1688
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• 2013

A rapid and sensitive method for determining usnic acid of Lethariella cladonioides in rat was established using high performance liquid chromatography (HPLC) quadrupole time-of-flight (QTOF) tandem mass (MS/MS). Rat plasma was pretreated by mixture of acetonitrile and chloroform to precipitate plasma proteins. Chromatographic separation was achieved on a column ($50{\times}2.1$ mm, $5{\mu}m$) with a mobile phase consisting of water (containing $5{\times}10^{-3}$ M ammonium formate, pH was adjusted to 3.0 with formic acid) and acetonitrile (20:80, v/v) at a flow rate of 0.3 mL/min. A tandem mass spectrometric detection with an electrospray ionization (ESI) interface was conducted via collision induced dissociation (CID) under negative ionization mode. The MS/MS transitions monitored were m/z 343.0448 ${\rightarrow}$ m/z 313.2017 for usnic acid and m/z 153.1024 ${\rightarrow}$ m/z 136.2136 for protocatechuic acid (internal standard). The linear range was calculated to be 2.0-160.0 ng/mL with a detection limit of 3.0 pg/mL. The inter- and intra-day accuracy and precision were within ${\pm}7.0%$. Pharmacokinetic study showed that the apartment of usnic acid in vivo confirmed to be a two compartment open model. The method was fully valid and will probably be an alternative for pharmacokinetic study of usnic acid.

• Proceedings of the PSK Conference
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• 2004.10a
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• pp.90-92
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• 2004

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.395.3-396
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• 2002

A simple, rapid and reliable high performance liquid chromatography (HPLC) method has been developed for the measurement of lansoprazole in human plasma, and the application of pharmacokinetic study has been evaluated. Omeprazole was used as an internal standard. After adding methyl tert-butyl ether, samples were stored at －7$0^{\circ}C$. The extracts were easily obtained only with pouring the organic phase. The mobile phase was prepared using acetonitrile and water at the volume ratio of 38:62. (omitted)

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.306.2-307
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• 2003

The purpose of this study was to investigate the effect of verapamil (5, 10, 20 mg/kg) on the pharmacokinetic parameters and the bioavailability of paclitaxel (50 mg/kg) orally coadministered in rats. The plasma concentration of paclitaxel with verapamil increased dose-dependently, and increased significantly in both coadministration (p<0.05) and pretreatment group (p<0.01) compared to that of control. (omitted)

• Bulletin of the Korean Chemical Society
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• v.35 no.6
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• pp.1845-1847
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• 2014

• Journal of the Korea Society for Simulation
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• v.10 no.3
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• pp.31-46
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• 2001

Repeated measurements on units under different conditions are common in biological and biomedical studies. In a number of growth and pharmacokinetic studies, the relationship between the response and the covariates is assumed to be nonlinear in some unknown parameters and the form remains the same for all units. Nonlinear random coefficient models are used to analyze such repeated measurement data. Extended least squares methods are proposed in the literature for estimating the parameters of the model. However, neither objective function has closed form expression in practice. This paper proposes Monte Carlo methods to estimate the objective functions and the corresponding estimators. A simulation study that compare various methods is included.

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.419.1-419.1
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• 2002

The purpose of this study was to report the pharmacokinetic changes of cyclosporine after oral administration of cyclosporine. 10 mg/kg. in rabbits coadministered or pretreated twice per day for 3 days with nimodipine. dose of 5 mg/kg, The area under the plasma concentration-time curve (AUC) of cyclosporine was significantly higher in rabbits pretreated with nimodipine than in control rabbits (p＜0.01). showing about 149% increased relative bioavailability. (omitted)

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.423.1-423.1
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• 2002

A simple. specific and sensitive method for the determination of cyclosporine A (CsA) in human serum has been developed by a high performance liquid chromatography/diode array detector (DAD) and applied to pharmacokinetic study of CsA. This method involves the use of solid phase extraction procedure following rapid protein precipitation with zinc sulphate from 1 $m\ell$ of human serum, using a disposable $C_{18}$ extraction cartridge. (omitted)

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.282.1-282.1
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• 2003

This study established a sensitive novel Quantification method for detecting glimepiride in human plasma using LC-MS/MS for pharmacokinetic studies. The mobile phase used after degassing was composed of 10 mM ammonium acetate and acetonitrile (20:80, pH 3.0), with flow rate of 200uL/min. One mL plasma were pipetted into glass tubes and spiked with 0.1 mL of internal standard solution. (omitted)

• Proceedings of the PSK Conference
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• 2003.04a
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• pp.306.1-306.1
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• 2003

The purpose of this study was to investigate the effect of ketoconazole(20mg/kg) on the pharmacokinetic parameters and the bioavailability of paclitaxel(40mg/kg) orally coadministered in rats. The plasma concentration of paclitaxel in combination with ketoconazole was increased significantly (coadministration p<0.05, pretreatment p<0.01) compared to that of control. (omitted)