Study On Pharmacokinetics And Residues Of Ofloxacin In Common Carp (Cyprinus Carpio)

Pharmacokinetics and several tissues of Ofloxacin were investigated, following single oral administration at dose of 20mg per kg body weight in common Carp(C.Carpio). The plasma and several tissues were collected at different interals after administration of Ofloxacin. The Ofloxacin concentrations in plasma and tissues were determined by high performance liquid chromatograph(HPLC) with a limit of detection of 0.05 u g/ml(g).Chromatography seperation was achieved on a ODS Hypersil-C18(150X 4.6mm, 5ym) column using a mixature of 0.05M potassium dihydrpgen phosphate, methanol and 0.5M tetrabutyl ammonium bromide(v/v 10:90:4) as the mobile phase. Detection wavelength is 294nm and mobile speed is 1 .Oml/min. Ofloxacin was extracted from tissues with dichloromethane at pH7.0, and the extracts were evaporated to dryness at 50 C water bath, dissolved in mobile phase after clean-up procedure by hexane and injected in the HPLC system with 20 u 1. The method is validated for the analysis of various tissues:plasma, skin, muscle and hepato-pancreas. Their linearity are all good over the concentration range(0.1~25ug/mL) in plasma and the concentration ranges(0.1~10ug/g) in tissues. The mean recoveries, within-day and between-day precisions fell within the ranges specified. The pharmacokinetic profiles following oral administration were determined utilizing a classical linear two-compartment open model and the pharmacokinetic equation is C=2.834e-0.0286t +50.234e-2.314t-53.258e-2.901t.The results indicated that the apparent volume of distribution(Vd/F),absorption half-life(t1/2ka),distribution half-life(t1/2) and elimination half-life (t1/2B) were 5.79L/Kg, 0.24h , 0.30h , 24.27h respectively, and the area under the curve(AUC) was 120.85ug h/mL; Following a single oral administration at the same dosage, Ofloxacin could be detected in skin , muscle and hepato-pancreas 9 days after dosing. And there was no residue higher than 0.08ug/g 9 days after withdrawal of administration in tissues. The results showed that the depletion of Ofloxacin in common caip(C.carpio) is slow with a long residue time .It was calculated that the withdrawl period should not be less than 9 days after oral administration of Ofloxacin in common carp(C. carpio).