The Residus Elimination Of Gamithromycin In Bovine

Gamithromycin is a new kind of semi-synthetic macrolide veterinary medicinal product for veterinary use.It has both bacteriostatic and bactericidal action,mediated through the disruption of bacterial RNA dependent protein synthesis.Gamithromycin has higher antimicrobial activity to Mannheimia haemolytica,Pasteurella multocida and Mycoplasma bovis,the bacterial pathogens most commonly associated with Bovine Respiratory Disease(BRD).The antibiotic has better pharmacokinetic characteristic,and it can be absorbed quickly,and can reach the C max quickly,more over,it can maintain a high concentration in animal’s lungs.The antibiotic has been extensive used abroad for treatment of cattle against bacterial infections of respiratory tract.In this study,a UPLC-MS/MS method was developed to detect gamithromycin in bovine plasma.The calibration curve for gamithromycin were linear in the range of 2~400 μg/kg(r>0.997).Concentration of three quality control samples of intra-day and inter-day precisions,and the low density of less than 10%,the Concentration and high Concentration less than 10%.The limit of detection(LOD)and the limit of quantificat ion(LOQ)of method were respectively 0.5 ng/mL and 2 ng/mL.The method was so simple,rapid,effective and that it is suitable to detect the gamithromycin in the bovine plasma.In the high(400 ng / mL),medium(40 ng / mL),low(2 ng / mL)matrix effect study,the sample was not shown to exhibit a corresponding matrix effect.We investigated the stability of the cipamycin stock solution,the stability of the sample after treatment,repeated freezing and thawing,and the long-term storage stability of the sample.The results of the test surface,gamycin in the above conditions have good stability.This experiment choose 20 healthy cow,half male and female,170~250 kg weight and Clinical observation for a week after purchase,before the test requirements o f clinical health,according to the requirements of test will test is divided into six groups,each group of 4 head,half male and female in each group.At different time points after the treatment,will be slaughtered cattle,slaughtered each 1 set,gathering the plasma,liver,kidney,muscle,fat,and the injection site.7 d after the treatment,21 d,35 d,48 d acquisition corresponding organs respectively,standby detection.The results showed that the concentration of gamithromycin in animal tissues was the highest at 7 days,the highest in liver was 3040 μg/kg,followed by kidney,2200μg/kg.Muscle and fat were 330 μg/kg,233 μg/ g.According to WT1.4 software,with reference to the maximum residue limit of EMA,it was estimated that 15% gamiomycin injection was subcutaneously and the treatment period was 48.4 days,43.8 days and 44 days.Because the muscle without MRL value,can not calculate the withdrawal period.Based on the total residuals and the maximum residue limits,it was suggested that 15% of the gamithomycin injection should be 49 d after subcutaneous injection.