Hye Young Ji

Quantification of doxazosin in human plasma using hydrophilic interaction liquid chromatography with tandem mass spectrometry

Hydrophilic interaction LC with MS/MS (HILIC-MS/MS) was described as a rapid, sensitive, and selective method for the quantification of doxazosin in human plasma. Doxazosin and cisapride (internal standard) were extracted from human plasma with ethyl acetate at alkaline pH and analyzed on an Atlantis HILIC Silica column with the mobile phase of ACN/ammonium formate (100 mM, pH 4.5) (93:7 v/v). The analytes were detected using an ESI MS/MS in the selective-reaction-monitoring mode. The standard curve was linear (r = 0.9994) over the concentration range of 0.2-50 ng/mL. The LOQ for doxazosin was 0.2 ng/mL using 100 microL plasma sample. The CV and relative error for intra- and interassay at four QC levels were 3.7-8.7% and 0.0-9.8%, respectively. The matrix effect for doxazosin and cisapride were practically absent. The recoveries of doxazosin and cisapride were 67.4 and 61.7%, respectively. This method was successfully applied to the pharmacokinetic study of doxazosin in humans.

Determination of metoclopramide in human plasma using hydrophilic interaction chromatography with tandem mass spectrometry

For the rapid, selective and sensitive analysis of metoclopramide in human plasma, hydrophilic interaction chromatography with electrospray ionization tandem mass spectrometric (HILIC/MS/MS) method was developed. This method involved liquid-liquid extraction with dichloromethane followed by separation on an Atlantis HILIC silica column using the mobile phase of acetonitrile-ammonium formate (100 mM, pH 6.5) (85:15, v/v). Analytes were quantified using electrospray ionization mass spectrometry in the selected reaction monitoring mode. The standard curve was linear (r(2)- 0.998) over the concentration range of 2.00 - 150 ng/mL using 50 microL of plasma sample. The coefficient of variation and relative error for intra- and inter-assay at four QC levels were 1.8 - 7.7% and -7.5 to 3.6%, respectively. The matrix effect for metoclopramide and levosulpiride (internal standard) was practically absent. The present method was successfully applied to the pharmacokinetic study of metoclopramide after oral dose of metoclopramide hydrochloride (10mg) to male healthy volunteers.

Liquid chromatography-electrospray lonization tandem mass spectrometric determination of lornoxicam in human plasma

A rapid, sensitive and selective liquid chromatography-electrospray ionization tandem mass spectrometric (LC-ESI-MS/MS) method for the determination of lornoxicam in human plasma was developed. Lornoxicam and isoxicam (internal standard) were extracted from human plasma with ethyl acetate at acidic pH and analyzed on a Sunfire C18 column with the mobile phase of methanol:ammonium formate (10 mM, pH 3.0) (70:30, v/v). The analyte was detected using a mass spectrometer, equipped with electrospray ion source. The instrument was set in the multiple-reaction-monitoring mode. The standard curve was linear (r = 0.9998) over the concentration range of 0.50-500 ng/mL. The coefficient of variation and relative error for intra-and inter-assay at four QC levels were 0.7 to 4.2% and -4.5 to 5.0%, respectively. The recoveries of lornoxicam and isoxicam were 87.8% and 66.5%, respectively. The lower limit of quantification for lornoxicam was 0.50 ng/mL using a 200 μL plasma sample. This method was successfully applied to a pharmacokinetic study of lornoxicam after oral administration of lornoxicam (8 mg) to humans.

Simultaneous determination of tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone in rat plasma by liquid chromatography-tandem mass spectrometry: application to a pharmacokinetic study of a standardized fraction of Salvia miltiorrhiza, PF2401-SF.

A rapid, sensitive and selective liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for the simultaneous determination of tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone, the active components of Salvia miltiorrhiza in rat plasma, was developed. After liquid-liquid extraction with tariquidar as an internal standard, tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone were eluted from an Atlantis dC18 column within 5 min with a mixture of methanol and ammonium formate (10 mm, pH 6.5; 85:15, v/v). The analytes were detected by an electrospray ionization tandem mass spectrometry in the selected reaction monitoring (SRM) mode. The standard curves were linear (r=0.999) over the concentration range of 0.25-80 ng/mL for tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone in rat plasma. The coefficients of variation and the relative errors of tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone for intra- and inter-assay at four quality control (QC) concentrations were 1.1-5.1% and -4.0-6.0%, respectively. The lower limit of quantification for tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone was 0.25 ng/mL from 100 microL of plasma. This method was successfully applied to the pharmacokinetic study of tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone after oral administration of PF2401-SF, the standardized fraction of Salvia miltiorrhiza enriched with tanshinone I, dihydrotanshinone I, tanshinone IIA and cryptotanshinone to male Sprague-Dawley rats.

Hydrophilic interaction chromatography-tandem mass spectrometric analysis of irbesartan in human plasma: application to pharmacokinetic study of irbesartan.

A hydrophilic interaction chromatography-tandem mass spectrometric method (HILIC/MS/MS) for the determination of irbesartan in human plasma was developed. Irbesartan and losartan (internal standard) were extracted from human plasma with ethyl acetate at acidic pH. The analytes were analyzed on a Luna HILIC column with the mobile phase of ACN-ammonium formate (50 mM, pH 6.5) (96:4, v/v) and detected by ESI MS/MS in the selected reaction monitoring mode. The standard curve was linear (r(2) = 0.9981) over the concentration range of 10-2500 ng/mL and the lower LOQ was 10 ng/mL using 100 microL of plasma sample. The CV and relative error for intra- and interassay at four QC levels were 2.9 to 8.1% and -2.7 to 2.3%, respectively. There were less absolute and relative matrix effects for irbesartan and losartan. The present method was successfully applied to the pharmacokinetic study of irbesartan after oral dose of irbesartan (150 mg tablet) to male healthy volunteers.

Hydrophilic interaction chromatography-tandem mass spectrometry of donepezil in human plasma: Application to a pharmacokinetic study of donepezil in volunteers

A selective, sensitive and rapid hydrophilic interaction liquid chromatography with electrospray ionization tandem mass spectrometry was developed for the determination of donepezil in human plasma. Donepezil was twice extracted from human plasma using methyl tert-butyl ether at basic pH. The analytes were separated on an Atlantis HILIC Silica column with the mobile phase of acetonitrile: ammonium formate (50 mM, pH 4.0) (85:15, v/v) and detected by tandem mass spectrometry in the selective reaction monitoring mode. The calibration curve was linear (r = 0.9994) over the concentration range of 0.10–50.0 ng/mL and the lower limit of quantification was 0.1 ng/mL using 200 μL plasma sample. The coefficient of variation and relative error for intra-and inter-assay at four QC levels were 2.7 to 10.5% and −10.0 to 0.0%, respectively. There was no matrix effect for donepezil and cisapride. The present method was successfully applied to the pharmacokinetic study of donepezil after oral dose of donepezil hydrochloride (10 mg tablet) to male healthy volunteers.

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, Vss and t1/2 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, Vss and t1/2 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, Vss and t1/2 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.

Pharmacokinetics of Lithospermic Acid B Isolated from Salvia Miltiorrhiza in Rats

The absorption and pharmacokinetics of an active component of Salvia miltiorrhiza, lithospermic acid B (LSB), was investigated after intravenous and oral administration of doses of 10 or 50 mg LSB/kg to rats. Concentrations of LSB were determined by a validated liquid chromatography/mass spectrometry (LC/MS/MS) assay method. After intravenous administration of 50 mg/kg, dose-normalized (10 mg/kg) area under the curve (AUC) (993 μg·min/ml) was significantly greater than that at 10 mg/kg (702 μg·min/ml). The slower clearance Cl-at 50 mg/kg could be due to saturable metabolism of LSB in rats, and this could be supported by significantly slower ClNR and significantly greater 24-h urinary excretion of LSB at 50 mg/kg than at 10 mg/kg. Following oral administration of LSB, the extent of LSB recovered from the entire gastrointestinal tract at 24 h ranged from 41.2% to 23.3%. Although LSB was not detected (limit of quantitation 10 ng/ml) in plasma after oral dose of 10 mg/kg, the absolute oral bioavailability at 50 mg/kg was 5%. Since LSB was shown to have low permeability through the Caco-2 cell monolayers, the low bioavailability of LSB could be due to poor absorption and metabolism.

Determination of tiapride in human plasma using hydrophilic interaction liquid chromatography-tandem mass spectrometry

A rapid, sensitive and selective hydrophilic interaction liquid chromatography-tandem mass spectrometric (HILIC-MS/MS) method for the determination of tiapride in human plasma was developed. Tiapride and internal standard, metoclopramide were extracted from human plasma with dichloromethane at basic pH and analyzed on an Atlantis HILIC silica column with the mobile phase of acetonitrile-ammonium formate (190 mM, pH 3.0) (94:6, v/v). The analytes were detected using an electrospray ionization tandem mass spectrometry in the multiple-reaction-monitoring mode. The standard curve was linear(r= 0.999) over the concentration range of 1.00-200 ng/mL. The coefficient of variation and relative error for intra- and inter-assay at three QC levels were 6.4~8.8% and -2.0~3.6%, respectively. The recoveries of tiapride ranged from 96.3 to 97.4%, with that of metoclopramide (internal standard) being 94.2%. The lower limit of quantification for tiapride was 1.00 ng/mL using 100 μL of plasma sample.

In vitro metabolism of Jaceosidin and characterization of cytochrome P450 and UDP-glucuronosyltransferase enzymes in human liver microsomes.

Jaceosidin is an active component in Artemisia species as well as Eupatorium species and it exhibits antiallergic, anticancer, antioxidant, anti-inflammatory, and antimutagenic activities. Jaceosidin was metabolized to jaceosidin glucuronide, 6-O-desmethyljaceosidin, hydroxyjaceosidin, 6-O-desmethyljaceosidin glucuronide, and hydroxyjaceosidin glucuronide in human liver microsomes. This study characterized the human liver cytochrome P450 (CYP) and UDPglucuronosyltransferase (UGT) enzymes responsible for the metabolism of jaceosidin. CYP1A2 was identified as the major enzyme responsible for the formation of 6-O-desmethyljaceosidin and hydroxyjaceosidin from jaceosidin on the basis of a combination of correlation analysis and experiments including immuno-inhibition, chemical inhibition in human liver microsomes, and metabolism by human cDNA-expressed CYP enzymes. Jaceosidin glucuronidation was catalyzed by UGT1A1, UGT1A3, UGT1A7, UGT1A8, UGT1A9, and UGT1A10. These results suggest that the pharmacokinetics of jaceosidin may be dramatically affected by polymorphic CYP1A2, UGT1A1, and UGT1A7 responsible for the metabolism of jaceosidin or by the coadministration of relevant CYP1A2 or UGT inhibitors or inducers.