| Baicalin and oxymatrine are two effective components of the Chinese traditional medicines which posses good therapeutic effect in clinical therapy to the hepatic injury, urgent or chronic hepatitis .In this paper, such analytical techniques as UV and HPLC were employed to investigate the physical chemical properties of baicalin and oxymatrine. The aim of this paper was to study the pharmacokinetics of these two drugs in rabbits and to illustrate the changes of pharmacokinetics when they were administered together.1. The study of analytical method of baicalin and its solubility and stability.A RP-HPLC method was developed to determine the concentration of baicalin. Separation was achieved on a Diamosil Cig column (200 4.6 mm, 5 m ID) with mobile phase of methanol-water-phosphoric acid(50:50:0.2, v/v/v) and the detection wavelength set at 277 ran. The stability of baicalin in aqueous solution was investigated employing HPLC method. The time when baicalin gained 10% loss was found as 18.1 h only and the degradation activation energy of baicalin was 79.1 kJ/mol. The most stable pH of baicalin was 4.1.The solubility of baicalin hi distilled water at 25 0.5 was determined as 110.7 ug/mL employing UV method. The solubility of baicalin of different pH was investigated. The solubility increased with the increase of pH and it had a significant increase after pH increased to 5.0.2. The study of analytical method of oxymatrine and its stability.ABSTRACTAn ion-paired RP-HPLC method was developed to determine the concentration of oxymatrine. Separation was achieved on a Diamosil Cig column (200 4.6 mm, 5 m ID) with mobile phase of acetonitrile-water (80:20, 5 mmol/L sodium octanesulfonate was contained and the pH was adjusted to 3.2 with phosphoric acid) and the detection wavelength set at 220 nm. The stability of oxymatrine in aqueous solution was investigated employing HPLC method. Oxymatrine is very stable, its concentration had almost no change even heated 14 h in warm bath of 100 The most stable pH of oxymatrine was 4.1.3. The study of analytical methods in vivo of baicalin and oxymatrine and their pharmacokinetics.A RP-HPLC method was developed to determine baicalin in rabbit plasma Rabbit plasma was pretreated by precipitating with acetonitrile. P-nitrobenzonic acid was used as the internal standard. The linear calibration curve was obtained in the concentration range of 0.5~200 mg/L (r=0.997 5) .The limit of quantitation of the method was 0.5 mg/L. The within-run and between-run RSD were within 5.4 % and 7.2 %, respectively. The average recovery was 100.1%. The pharmacokinetic parameters in 9 rabbits were determined respectively when they were administered intravenous 40 mg/kg baicalin(single formulation) and 40 mg/kg baicalin and 40 mg/kg oxymatrine together(conipound formulation). The results were as follows: /i/2a were 2.9 1.1 min and 2.8 1.7 min, t1/2 were 14.6 2.8 min and 12.7 5.5 min, AUC0~ were 2077.9 556.4 g-min-mL'1 and 1781.2 462.4 ng-min-mL-1, respectively. When rabbits were administered with oral doses of 40, 200, 400 and 800 mg/kg, the chromatogram of baicalin was not detected using previous method in this paper. It shows that rabbits perhaps have no absorption or at least have a very bad absorption when taken baicalin orally.An ion-paired RP-HPLC method for determining oxymatrine in rabbit plasmaABSTRACTwas developed. After precipitated with 6% HCLO4 and basificated by 20% NaOH, the organic phase was evaporated to dry with the nitrogen stream and the residue was dissolved with mobile phase. Phenacetin was used as the internal standard. The linear calibration curve was obtained in the concentration range of 0.5~100 mg/L (r=0.996 5) . The limit of quantitation of the method was 0.5 mg/L. The within-run and between-run RSD were within 6.6% and 13.8%, respectively. The average recovery was 99.1%. The pharmacokinetic parameters in 8 rabbits were determined respectively when they were administered intravenous 40 mg/kg oxymatrine(single formulati...
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