• Korean Journal of Pharmacognosy
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• v.35 no.1 s.136
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• pp.22-27
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• 2004

Scutellaria baicalensis Georgi is one of most important medicinal herbs in traditional chinese medicine. The object of this study was to determine the effects of the water extracts of Scutellaria baicalensis (SB) on the anxiolytic-like activities in the elevated plus-maze (EPM) test. The watεr extracts of SB (100, 200, or 400 mg/kg) were orally administered to male SD rats for 3 days, and behavioral tests for the anxiolytic activity were performed. SB (100, 200, or 400 mg/kg) significantly increased in time-spent and arm entries into the open arms of the EPM compared with the control group. Futhermore, those anxiolytic-like activities of SB were antagonized by flumazenil (a $GABA_A$ antagonist, 3 mg/kg), but not by pindolol (a $5-HT_{1A}$ antagonist, 10 mg/kg). SB did not cause myorelaxant effects in the horizontal wire test at any dosage regimen. Therefore, these findings suggest that SB promote the anxiolytic-like activity mediated by GABAergic nervous system in rats.

• Journal of Pharmaceutical Investigation
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• v.36 no.5
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• pp.331-338
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• 2006

A rapid, selective and sensitive reverse-phase HPLC methods for the determination of atenolol and chlorthalidone in human serum and whole blood were validated, and applied to the pharmacokinetic study of atenolol and chlorthalidone combination therapy. Atenolol and an internal standard, pindolol, were extracted from human serum by liquid-liquid extraction, and analyzed on a $\mu$-Bondapak C18 $10-{\mu}$ column in a mobile phase of methanol-0.01 M potassium dihydrogenphosphate(30:70, v/v, adjusted to pH 3.5) and fluorescence detection(emission: 300 nm, excitation: 224 nm). Chlorthalidone and an internal standard, probenecid, were extracted form human whole blood by liquid-liquid extraction, and analyzed on a Luna C18 $5-{\mu}$ column in a mobile phase of acetonitrile containing 77% 0.01 M sodium acetate and UV detection at 214 nm. These analysis were performed at three different laboratories using the same quality control(QC) samples. The chromatograms showed good resolution, sensitivity, and no interference by human serum and whole blood, respectively. The methods showed linear responses over a concentration range of 10-1,000 ng/mL for atenolol and 0.05-20 ${\mu}g/mL$ for chlorthalidone, with correlation coefficients of greater than 0.999 at all the three laboratories. Intra- and inter-day assay precision and accuracy fulfilled international requirements. Stability studies(freeze-thaw, short-, long-term, extracted sample and stock solution) showed that atenolol and chlorthalidone were stable. The lower limit of quantitation of atenolol and chlorthalidone were 10 ng/mL and 0.05 ${\mu}g/mL$, respectively, which was sensitive enough for pharmacokinetic studies. These methods were applied to the pharmacokinetic study of atenolol and chlorthalidone in human volunteers following a single oral administration of Hyundai $Tenoretic^{\circledR}$ tablet(atenolol 50 mg and chlorthalidone 12.5 mg) at three different laboratories.