| OBJECTIVETo study the pharmacokinetics of pazufloxacin mesilate injection in healthy volunteers.The demonstration of pharmacokinetic characteristics to provide reasonable clinical administration regimen and accurate scientific evidence ,then obtain effective, safe and reasonable application on clinic.METHODS1. Establish the analytic methodologyThe plasma samples were determined for pazufloxacin mesylate bya high-performance liquid chromatography method. HPLC: Use Kromasil C18 column (150mm×4.6mm,5μm),the mobile phase consisting of 350mL methanol, 650mL water(35/65,v/v)and 6.5mL triethylamine(phosphoric acid, pH=3.0). The flow rate was 1.OmLmin-1, column temperature at room temperature, the detection was set at 244nm. To evaluate the methodology by detecting the linear range and limit of test, method recovery rate, drawn rate, RSD of inter-day and intra-day, and then to prove whether it could be used for the pharmacokinetic studies for pazufloxacin mesylate or not. Plasma samples of pazufloxacin mesylate were assayed using the RP-HPLC method.2. Pharmacokinetics of Pazufloxacin mesylate injection in healthy volunteers(1) Single-dosea Method: After an overnight fasting, 10 volunteers received 300 mg intravenous administration of pazufloxacin mesylate (i.v.30min).Water, lunch and dinner were given to all volunteers according to a time schedule.b Plasma sample: Approximately 3mL of plasma samples for pazufloxacin mesylate were collected immediately before (predose) and at 10min, 20min, 30min, 45min, 1h, 1.5h, 2h, 3h, 4h, 6h, 8h. Plasma samples were centrifuged at 15000g for 8 min. Prior to analysis, the blood samples were determined by the HPLC assay.(2) Mutiple-dosea Method: 10 volunteers received mutiple dose of pazufloxacin mesylate injection. The multiple-dose study was carried out according to the regimen (300mg i.v. twice a day, for 5 days, intervals for 12h).b Plasma sample: Approximately 3mL of plasma samples for pazufloxacin mesylate were taken predose and at 0.5h, 12h(on day 1), Oh and 12h(on days 2 to 4), 15min, 30min, 35min, 45min, 1h, 1.5h, 2h, 4h, 6h, 8h, 10h, 12h follwing intraveous administration(on day 5). Plasma samples were centrifuged at 15000g for 8 min. Plasma samples of pazufloxacin mesylate were determined using the RP-HPLC method.(3) Data analysis:T_max and C_max were actual value, and calculated eliminate phase eliminate rate half-time, C_avg, C~ss_min and C~ss_max. Other pharmacokinetic parameters were calculated by statistical software 3P97.RESULTS1. analytic methodologyIn this experiment, the number of theoretical plate of HPLC was 4441.6, there existed a distict separation between pazufloxacin mesylate in the plasma and the baseline. There was a significant correlationbetween pazufloxacin mesylate concentrations and area under curve in the scope of 0.078~ 10 mg-L~-1 in plasma.Calibration equation of pazufloxacin in plasma was C=4.014×10~-6 A-0.0464 (n=6, r=0.9998). The limit of test for pazufloxacin was 25 ng-mL~-1 in plasma.Under this condition, the method recovery rate of high concentration(5.00 mgL~-1), middle concentration 1.25 mg·L~-1) and low concentration(0.156 mg·L~-1) were (96.50±4.09) %, (94.84±2.50) % and (89.53±4.48) % respectively. The drawn rates were (92.91±0.60) %, (89.77±2.28) % and (90.33± 6.32) %. RSD of inter-day were 0.83 %, 4.72 %, 6.99 %, intra-day were 0.46 %, 3.65 %, 4.60 % respectively. Freeze-melt study indicateded that pazufloxacin was stable in plasma for at least 14 days when the plasma samples were stored upright at -20℃.2. Pharmacokinetics(1) Single-dose: The pharmacokinetic parameters obtained from the single-dose study were as follows: T_max (0.57±0.12) h, C_max(6.36±1.64) mg-L~-1, AUC(0-8) (15.68±3.61) mg·h·L~-1, T1/2ke (1.92±0.41) h, CL (20.06±4.52) L·kg·h~-1.(2)Mutiple-dose: The steady-state pharmacokinetic parameters were: T_max (0.55±0.11) h, C~ss_min (0.096±0.036) mg·L~-1, C~ss_max (10.43±3.81) mg·L~-1, C_avg (1.83±0.75) mg·L~-1, AUC (21.24±8.91) mg-h·L~-1,T1/2ke (1.68±0.69)h.3. OthersNone of the volunteers had to be withdrawn from the study. No abnormal subjective or objective findings, physical findings, electrocardiographic findings, or laboratory test values were detected in the process of the experimentation.CONCLUSION1. This RP-HPLC method is simple, sensitive and accurate. It is suitable for routine determination of pazufloxacin mesylate levels in human plasma and for its pharmacokinetic study. There exsisted a clear correlation between pazufloxacin mesylate concentrations and area under curve in the scope of 0.078~10 mg·L~-1 in plasma(r=0.9998). The detection was set at 244 nm. The retention time of pazufloxacin was 5.7 min. The limit of test for pazufloxacin was 25 ng·mL~-1 in plasma; RSD of inter-day and intra-day were less than 10%; method recovery rate and drawn rate were more than 92 %; freeze-melt study showed that pazufloxacin was stable in plasma for at least 14 days when the plasma samples were stored upright at -20℃. Therefore, all these conditions were conformed to the prescript of 2000 Pharmacopoeia about study of pharmacokinetics.2. All calculated pharmacokinetic parameters of pazufloxacin mesylate injections were most similar to the overseas reported pharmacokinetics parameters of pazufloxacin. There existed some difference on AUC, possibly due to the time of collected sample, sample types, different... |
PDF Full Text Request