Study On The Quality Control And Pharmacodynamics Of Compound Enrofloxacin Granules

In this study,Enrofloxacin and antimicrobial synergist Trimethoprim were prepared to compound enrofloxacin granulesby by conventional wet granulation.Its quality control,content determination,acute toxicity test and in vitro antibacterial test lay the foundationfor the drug using in the veterinary clinical and entering the veterinary drug market.The minimum inhibitory concentration(MIC)and the minimum bactericidal concentration(MBC)of enrofloxacin and trimethoprim were determined by the ratio dilution method.The results of the MIC(μg / mL)of enrofloxacin to five common bacteria(Pasteurella multocida,Streptococcus agalactiae,Salmonella,Escherichia coli and Staphylococcus aureus)were 0.2520,0.0315,2.0163,0.0630,0.2520.The MBC(mg/mL)for the five bacteria above was 0.5041,0.0630,4.0325,0.1260 and 0.5041.The MIC(μg/mL)of trimethoprim for these five bacteria was 0.2542,2.0338,0.5084,2.0338,1.0169.The MBC(mg/mL)of trimethoprim for these five bacteria were 0.5084,4.0675,1.0169,4.0675,2.0338.The results of the combined drug susceptibility test showed a synergistic effect on streptococcus agalactiae,Salmonella and Staphylococcus aureus after combination with enrofloxacin and trimethoprim,and showed anadditive effect onPasteurella multocida and Escherichia coli.According to the diameter of the inhibition zone,the optimal ratio of enrofloxacin and trimethoprim was 2: 1.The formulation was enrofloxacin: 5%,trimethoprim 2.5%,β-cyclodextrin 92.5 %.Quality control and content determination showed its particle size,dry weight loss,solubility and other indicators are consistent with the 2015 version of the Chinese veterinary Pharmacopoeia standards.The content of enrofloxacin and trimethoprim was determined by ultraviolet spectrophotometry.The content of enrofloxacin was 48.86 mg/g and the content of trimethoprim was 24.39 mg/g at 323 nm and 292 nm.The results showed that the LD50 of the compound enrofloxacin granules was 2381.92 mg/kg and the 95% confidence interval of LD50 was 1947.58 ~ 2913.13 mg/kg,which belonged tolow toxicity drugs.The in vitro antibacterial test of compound enrofloxacin granules showed that the MIC(μg/mL)of the five common bacteria were 16.0175,4.0044,8.0088,16.0175 and 4.0044.The MBC(mg/mL)for these five bacteria were32.035,8.0088,16.0175,32.035,8.0088.From the above results,the compound enrofloxacin granules had good antibacterial effect,and trimethoprim had significant effect on antibacterial synergistic effect of enrofloxacin,and the antibacterial effect after combination therapy was several times higher than that of single drug.