Study On The Pharmacokinetics And Residues Elimination Of Decoquinate Suspension In Brolier

Coccidiosis caused by several species of Eimeria pose significant problems for the poultry industry all over the word, and it has been listed as the one of the top five diseases in poultry industry by USDA(United States Department of Agriculture).At present,coccidiostats as food additives are the main choice to fight against coccidiosis. Decoquinate is a quinolone derivative, developed as anticoccidial drug in1960s. Decoquinate has attracted wide attention from the veterinary medicine experts, because of its low level of toxicity, good tolerance, long duration of action. By studying the pharmacokinetics characteristics and residue elimination of decoquinate suspension in broiler, the purposes was to guide the clinical rational drug use.1. Pharmacokinetics of decoquinate suspension in broilersDecoquinate suspension (10mg/kg b.w.) was orally administered and decoquinate solution (2mg/kg b.w.) was injected intravenously (i.v) to50-day-old broilers in a parallel study design. Blood samples were collected according to the given time, the samples were extracted with acetonitrile and ethyl acetate, the concentration of the drug in plasma were determined by high performance liquid chromatography (HPLC). Pharmacokinetic parameters were obtained by the Kinetica pharmacokinetic analysis software.After single intravenous administration of decoquinate solution, the main pharmacokinetic parameters of decoquinate were as follow:Ti/2p was29.22h, MRT was41.31h, CLB was3.55ml/(min·kg), AUC was4945.91(mg/L)·h, Vz was7.84L/kg. After single oral administration of Decoquinate Suspension, almost all the blood drug concentration was below the level of limit of quantitation (LOQ). Drug absorption was irregular, blood drug concentration has changes in different individual.2. Residue elimination of decoquinate suspension in broilersA rapid, sensitive and reliable high performance liquid chromatography (HPLC) method was developed and validated for the analysis of decoquinate in chicken tissues. Decoquinate were extracted using acetonitrile by liquid-liquid extraction, defatted with n-hexane. The mobile phase was acetonitrile-methanol-water. The test results showed that concentration of decoquinate had a good linear coefficient relation (R2=0.9997) in the range of0.1-4.0mg/L. The limit of detection (LOD) was O.lmg/kg and the limit of quantitation (LOQ) was0.2mg/kg. The average recoveries of decoquinate spiked in broiler tissues at concentration of0.2,0.5and1.Omg/kg were between74.06%and88.63%, the within-day coefficient of variation (CV) and between-day CV were1.09%～5.20%and2.80%～9.01%. The established method can be used for residue analysis of decoquinate in broiler tissues.Thirty healthy broilers were administered decoquinate suspension per day at highest dosage for ten successive days. Six medicated broilers were randomly slaughtered at0,1,3,5and7days after the cessation of the medication period. Decoquinate in broiler tissues was determined with the established method above. The result showed that decoquinate were quickly eliminated in muscle, and slowly eliminated in skin+fat. The data were analysed with WT1.4program. The withdrawal period was2.7d in skin+fat and0d in other tissues. The results showed that the withdrawal period of decoquinate suspension in broilers was3days.