Study On Florfenicol Solution Formulation, Stability Test And Clinical Efficacy

Florfenicol, a derivative of chloramphenicol, is only permitted to use in animals. Due to broad spectrum, good absorption, wide distribution, no potential risk in aplastic anemia, and safety dose range, it is widely used in veterinary clinical practice. There is broad market for its formulation. In this study, florfenicol solution formulation is prepared. Moreover, the stability test, maximum inhibition concentration (MIC) test, in vitro inhibition test, and clinical efficacy test on Escherichia coli-infected broiler chicken were conducted.Florfenicol solution formulation is prepared successfully on the basis of a solvent dimethylformamide and a stabilizer polyethylene glycol 200. Based on Technological Criteria of the Experiment on Veterinary Medicine Stability issued by Agricultural Ministry, P. R. China, the study on the stability of florfenicol was performed for 6 months at a temperature of 40 ℃ with 75% of relative humidity and ten-day light acceleration test with illumination 4500±500Lx, and twenty four-month long term test also were conducted. The major items for stability were determined. The obtained results indicated the content, appearance, clarification degree, and degradation product from the formulation are met the requirements on the development of new drug formulation regulated by National Department of Agriculture. In addition, the test for the florfenicol preparation in tap water showed it has better quality even after 24 h.The in vitro antibacterial test was undertaken to determine the inhibitory effect of florfenicol on Escherichia coli O₁-C₈4012, Staphylococcus SD-1 and Salmonella C79-13 by adding 0.05 ml of diluted florfenicol solution (1:800, 1:400 and 1:100, respectively) and using Ciprofloxacin as the control. The result indicated that florfenicol had the marked antibacterial effect and that its inhibitory intensity showed a positive relation with its concentration. The diluted florfenicol solution of 1:800 still showed a significant antibacterial effect on Escherichia coli, Salmonella typhi and Staphylococcus aureus, and the inhibitory effect on Staphylococcus was the most significant among these treatments. The MIC values were 3.125μg/ml for Escherichia coli and Salmonella typhi and 6.25μg/ml for Staphylococcus aureus. The antibacterial effect of diluted florfenicol solution of 1:400 was similar to or better than that of ciprofloxacin.The last trial was conducted to determine the antibacterial effect of florfenicol on chicken artificially infected with Escherichia coli O₂ (1.0×10⁷) by supplementing 50 mg/L, 100 mg/L and 200 mg/L florfenicol solution to drinking water, respectively. The control was fed to diets mixed with 200 mg/kg florfenicol powder. The result showed that 100 mg/L and 200 mg/L of florfenicol solution could effectively protect chicken against Escherichia coli. The survivor rate and daily weight gain were 86.0-88.0% and 35.6-39.0g, respective. Its effectiveness was markedly better than those of 50 mg/L florfenicol solution and the control. 50 mg/L florfenicol solution could not effectively control Escherichia coli, as evidenced by the in vitro antibacterial test. Moreover, 500 mg/L was seem safe to animal. Based on these results, a concentration of 50 mg/L florfenicol solution and 5-7 days of the treatment period are recommended.