The Residue Elimination Profile Of Compound Florfenicol Injectable Solution In Pigs

Compound Florfenicol Injectable Solution which is made up of Florfenicol and Flunixin Meglumine, is clinically used for the treatment of swine respiratory tract infections caused by actinobacillus pleuropneumoniae. The method of high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) and high performance liquid chromatography (HPLC) were established to detect the florfenicol, florfenicol amine and flunixin in swine tissues respectively, in order to provide reliable technical means for drug residue determination. The residue elimination profile of Compound Florfenicol Injectable Solution in pigs were studied in this study, which provide a theoretical basis for the clinical use of this compound and its withdrawal time in pigs.1 The HPLC-MS/MS method for determination of florfenicol and florfenicol amine residues in porcine tissuesThe swine tissue samples (liver, kidney, musule, skin and fat) were extracted with a mixture of ammonia water and ethyl acetate(v/v 3:97), and the fat was removed by hexane. The mobile phase was acetonitrile and 0.1% formic acid water (0-1.5 min 20% acetonitrile,4-7 min 80% acetonitrile,8-15 min 100% acetonitrile,16-25 min 20% acetonitrile), and the gradient elution program was used. Quantification was carried out by positive/negative electrospray ionization (ESI+/ESI-) and Multiple Reaction Monitoring (MRM) mode. The results showed that the calibration curves showed good linearity at concentrations of 10-2000 ng/ml. The relative coefficients were over than 0.99. Both the limit of detection (LOD) of florfenicol and florfenicol amine was 10 μg/kg while the limit of quantification (LOQ) was 20 μg/kg. The average recoveries of florfenicol and florfenicol amine in porcine tissues fortified in the range of 20～4000 μg/kg were from 79.26% to 113.26%, The intra-day and inter-day coefficient of variation (CV) were less than 10%. The established method can be used for residue analysis of florfenicol and florfenicol amine in porcine tissues.2 Determination of flunixin residues in porcine tissues by HPLC methodThe sample was extracted with a mixture of trichloroacetic and acetonitrile, and the fat was removed by hexane. PCX columns were used to purify the sample. The mobile phase was methanol and 0.05 mol/L phosphate buffer, the ultraviolet detector was used for detection at wavelength of 333 nm. The results showed that the calibration curves were of good linearity at the concentrations of 0.02～5 μg/ml(R2= 0.9994). The LOD were 15 μg/kg and the LOQ was 30 μg/kg in tissues of kidney and liver, The LOD were 6 μg/kg and the LOQ was 10 μg/kg in skin+fat. The LOD were 10 μg/kg and the LOQ was 25 μg/kg in muscle. The average recovery rates of flunixin in kidney and liver fortified at 30、200 and 1000 μg/kg were 74.78%～84.67%、83.49%～86.16% respectively. The average recovery rates of flunixin in skin+fat fortified at 10、200 and 1000 μg/kg were 83.88%～89.26%. The average recovery rates of flunixin in muscle fortified at 25、200 and 1000 μg/kg were 72.10%-89.18%. The intra-day and inter-day CV were less than 10%. The established method can be used for residue analysis of flunixin in porcine tissues.3. The residue elimination profile of Compound Florfenicol Injectable Solution in pigsTwenty-five health crossbred pigs were administered Compound Florfenicol Injectable Solution at 40 mg/kg b.w (Florfenicol counted) i.m. Five pigs were respectively slaughtered at 1 d、6 d、11 d、16 d and 21 d after withdrawal. Florfenicol, florfenicol amine and flunixin in porcine tissues were determinted by the established method above. The results showed that the residual of florfenicol was highest in kidney and lowest in muscle after first day withdrawal, except for the injection site. the residual of florfenicol amine was highest in liver and lowest in muscle and skin+fat after first day withdrawal. the residual of flunixin was highest in kidney and skin+fat and lowest in muscle after first day withdrawal.The results showed that florfenicol was quickly eliminated in muscle, and slowly eliminated in kidney, liver and skin+fat, especially in liver. That means the liver was the target organ of florfenicol. The raw data were analysed with software WT1.4. The simulation results showed that the withdrawal period was 7.21 d in skin+fat,4.62 d in liver and 10.02 d in kidney for florfenicol. The withdrawal period estimated by the measured data was 11 d in muscle. Flunixin was quickly eliminated in muscle, The concentrations of flunixin in porcine tissues were lower than LOD after 11d withdrawal. The withdrawal period estimated by the measured data was 5.95 d in muscle,11 d in the other pig tissues. Results of this research showed that the withdrawal period of Compound Florfenicol Injectable Solution was 11 d in pig.