Study On The Pharmcokinetics And Residue Of Tinidazole In Chicken

The studies on the Pharmacokinetics of Tinidazole (30mg/kg.b.w.) in 20 chickens after single dose of intravenous and oral administration, and on the residues of Tinidazole (30mg/kg.b.w. oral administration, five days) in tissues are reported in this paper. Plasma samples were collected from brachial vein at every different interval after administration. Tinidazole in the plasma was extracted by dichloromethane: methanol(98:2 v/v) ,and evaporated to dryness at 50-5 5 water bath. The contents were determined by reversed-phase high performance liquid chromatography. Tinidazole was separated on Spectrasystem HPLC instrument using YWG-C 18 column (250 4.6mm, 10 u m),the mobile phase consisted of a degassed mixture methandol:20% acetonitrile: water (25:25:50 v/v), the range of 0.125~64.0 g/ml (r=0.9998). The plasma calibration curve was linear in the range of 0.2~51.2 g/ml (r=0.9989) ,the average recovery was >90%,the inter-day coefficient of variance was <5%(n=3),and intra-day coefficient of variance was<10%.The single dose intravenous and oral administrations concentration-time data were analyzed by pharmacokinetic compartment analysis soft (PKANALYST). The procession after intravenous was fit the two-compartment open model, and its main pharmacokinetic parameters were followed :t1/2, 0.279h;t]/2u 4.705h; Vc 0.857L/kg; Vdss 1.293IAg; Clb 0.206L/kg.h; AUC 153.280 mg.h/L. Theprocession after oral administration fit one compartment model, and its main pharmacokinetic parameters of Tinidazole in chickens were as follows: ka 1.915h'';k 0.099hf'; V 2.600L/kg; Clb 0.259L/kg.h ; tl/27.173h; AUC 123.446 mg.h/L;F 80.536% ;Tmax 2. 5h;Cmax 10. 720 g/ml. According to the parameters of single dose administration, the administration scheme was followed :Dosing interval 24h;Priming dose 34.484mg/kg;Maintenance dose 30mg/kg;Average steady state concentration 4.275mg/kg.Residues were determined at different interval of 12,24,48,72h after continuous oral administrations. Then collect the samples of livers, muscles, kidneys, and fats after killing every group of the chickens. The samples were determined at the conditions, which was as the same as that of plasma. At 12h, Tinidazole in the muscles is higher than any other tissues then in fats and kidneys, and the livers are the lowest. Tinidazole in muscles could be determined at 72 hours, and could not be detected in other three kinds of tissues after 24 hours. Then suggested that the withdrawal time of Tinidazole should be 5 days.