| This study developed a method to detect flumequine in Sciaenops ocellatus and Lateolabras janopicus plasma and tissues using reverse phase high performance liquid chromatorgraphic method (RP-HPLC). Pharmacokinetics and residues of flumequine were investigated, following single intraperitoneal injection at a dose of 20mg/kg and single oral administration at a dose of 20mg/kg in healthy Sciaenops ocellatus and Lateolabras janopicus.The plasma and two tissues (muscle, liver) were collected at different intervals after administration of flumequine at 25.0±1.5℃. Dichloromet-hane was used as extractant. The extracts were evaporated to dryness at water bath of 60℃and were dissolved in mobile phase. Then the fat of the solute was degreased by hexane and analysed by RP-HPLC. The mobile phase was acetonitrile, tetrahydrofuran and 0.02mol/L H3PO4 = 16:12:72 (V/V/V). The chromatographic column was Zorbax SB-C18(5μm, 150×4.6mm, I.D) column and ultraviolet detector was set at 324nm. The mean recoveries for all samples were all exceed 85.55%, lntra-day CV and inter-day CV are under 4.63% and 5.03% respectively. Both LOD can meet the requirement of the residual detection.The concentration-time data of flumequine in plasma of healthy Sciaenops ocellatus and Lateolabras janopicus after single intraperitoneal injection was fitted to two-compartment model with first order absorption. The main pharmacokinetic parameters for plasma of Sciaenops ocellatus were: distribution half-life (t1/2α), absorption half-life (t1/2ka) and elimination half-life (t1/2β) were 2.844h, 0.061h and 28.69h respectively. The area under the curve (AUC), the time to peak concentration (Tmax) and the peak concentration (Cmax) were 119.098μg/h·ml,10min and 22.423μg/mL respectively. The main pharmacokinetic parameters for plasma of Sciaenops ocellatus were: t1/2α, t1/2ka and t1/2βwere 0.71 h, 0.012h and 8.163h respectively. AUC, Tmax and Cmax were 76.205μg/h·ml,10min and 22.329μg/mL respectively.The concentration-time data of flumequine in plasma of healthy Sciaenops ocellatus and Lateolabras janopicus after single oral administration was fitted to two-compartment model with first order absorption. The main pharmacokinetic parameters for plasma of Sciaenops ocellatus were: distribution half-life (t1/2α), absorption half-life (t1/2ka and elimination half-life (t1/2β) were 8.327 h, 0.003h and 944.7 h respectively. The area under the curve (AUC), the time to peak concentration (Tmax) and the peak concentration (Cmax) were 280.287μg/h·ml,4h and 4.135μg/mL respectively. The main pharmacokinetic parameters for plasma of Sciaenops ocellatus were: t1/2α, t1/2ka and t1/2βwere 2.281h, 2.008h and 44.304h respectively. AUC, Tmax and Cmax were 17.356μg/h·ml,4h and 1.809μg/ml respectively.The results showed that the pharmacokinetic character of flumequine in healthy Sciaenops ocellatus and Lateolabras janopicus was as follows: flumequine was absorbed fast and the time to peak concentration was short; Flumequine distributed extensively in Sciaenops ocellatus and Lateolabras janopicus; The drug was slowly eliminated in liver than in plasma and muscle after a single oral aministration in healthy Sciaenops ocellatus; The character of residue and elimination was both residual quantity of flumequine and elimination rate were different significantly in every tissues. The concentration of flumequine in liver was much more higher than other tissues and showed the slower depletion among two tissues, The target tissue of residue was liver. From the formula of withdrawl period, it was suggested that the withdrawl period should not be less than 5 days after single oral administration of flumequine in healthy Sciaenops ocellatus and Lateolabras janopicus... |
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