Preliminary Studies On The Pharmacokinetics And Residus Of Cefotixime In Laying Hens

Cefotaxime(CTX)is a human antibiotic.however,it has been used for the production of poultry and livestock in recent years because of its strong antibacterial activity against Pasteurella,Salmonella Pullorum and Chicken Colibacillosis.In recent years,China has a big consumption on poultry meat and eggs,but drugs residue often threaten the safety of poultry products due to the lack of management control.When we face the objective fact of cefotaxime abusing,little data can be accessed because of lacking research on metabolism of cefotaxime in poultry.To support regulation of food safety and facilitate food quality,The main contents of this study were as follows:1.A validated method for determination of cefotaxime and its main metabolites in laying hens by UPLC-MS/MSEstablish the method of cefotaxime and its main metabolite desacetylcefotaxime in muscle,liver,kidney,egg and plasma by ultra performance liquid chromatography-tandem mass spectrometry(the processing method,condition optimization of chromatographic and mass spectrometry)and verify its analysis method.The QuEChERS(Quick,Easy,Cheap,Effective,Rugged,and Safe)method was used for sample preparation,the samples were extracted with acetonitrile-water,methanol;And cleaneded up by dispersive solid-phase extraction using C18 dispersant sorbent,then degreased with hexane.Cefotaxime and desacetylcefotaxime were separated on an Agilent Eclipse Plus C18 column(3.5 ?m,2.1x100 mm)using a mobile phase of 0.2%formic acid(A)-acetonitrile(B)by gradient elution.The electrospray was operated in the positive ionization mode(ESI+),cefotaxime and desacetylcefotaxime were identified under multiple reaction monitoring(MRM)mode.The method was quantified by matrix-matched standard curves.The results showed that the concentration of cefotaxime and desacetylcefotaxime were both well lined in all tissues with correlation coefficients more than 0.999.The detection limits and quantification limits for cefotaxime were 0.07-0.35 ?g/kg,0.23?1.15 ?g/kg,respectively;And the detection limits and quantification limits for desacetylcefotaxime were 0.14?0.70 ?g/kg,0.99?4.95?g/kg,which met the basic quantitative requirements.Three concentration levels of cefotaxime and desacetylcefotaxime were analysed.The average recoveries of cefotaxime and desacetylcefotaxime were 88.0%?98.8%?88.7%?113%,respectively;The intra-day coefficients of variation was from 2.0%to 9.4%.The results demonstrated that the method was simple,quick,sensitive and reliable,and was fully meet the requirements of biological sample analysis.2.Pharmacokinetics of cefotaxime in laying hens plasma.24 laying hens were randomly divided into two groups,the dose of 20mg/kg BW cefotaxime was administered to them by single intramuscular and intravenous injection,respectively,the chicken plasma was collected at different time points.Cefotaxime and desacetylcefotaxime in the plasma sample were measured using an UPLC-MS/MS method and the data was analysed by WinNonlin 6.3 software with the non-compartmental model.The main parameters of cefotaxime pharmacokinetics in hens plasma showed that the distribution of cefotaxime was rapid and wide in laying hens,the concentration of plasma was high and the elimination was quick.The main parameters of desacetylcefotaxime pharmacokinetics in hens plasma by Intramuscular administration showed that the plasma concentration of desacetylcefotaxim went up rapidly and down gradually with the metabolism of cefotaxime,the T1/2p were(5.00±1.41)h and(4.56±0.49)h after single intravenous and intramuscular administration;and the T1/2? of cefotaxime were(2.11±0.03)h?(2.16±0.02)h),showing a stable generation and elimination.3.The residues of cefotaxime and desacetylcefotaxime in laying hens tissues and eggsIn this paper,the distribution and elimination of cefotaxime and its metabolite desacetylcefotaxime residues in different parts of laying hens as well as in eggs were studied.It was performed in laying hens,which were administraed cefotaxime for 5 consecutive days(20 mg/kg BW),and then the plasma,kidney,liver,muscle,and Eggs,were collected at different times after the end of treatment.UPLC-MS/MS was used to detect cefotaxime and desacetylcefotaxime residues.The results showed that,both cefotaxime and deacetylcefotaxime residues were rapidly eliminated at the 1st day after withdrawal,but the elimination rate for desacetylcefotaxime was relatively slow.cefotaxime had the lowest rate of elimination in eggs,therefore,eggs can be used as the sample of residual detection in laying hens.The elimination rate of deacetylcefotaxime in the liver tissue was very slow,the liver can be used as targets for deacetylcefotaxime residues detection in broiler.