Preparation And Pharmacodynamic Evaluation Of Acetylisovaleryltylosin Nanoemulsion

Objective: We prepared Acetylisovaleryltylosin Nanoemulsion(AIV-NE) and studied itsstability, safety and therapeutic efficacy.Method:(1)We determined the oil and cosurfactant according to the solubility of Acetyl-isovaleryltylosin in them, screed the surfactant and K_mby studying the pseudoternary phasediagram. The structure type, shape and particle diameter distribution of AIV-NE wereinvestigated by staining method, transmission electron microscope and laser particle sizeanalysator respectively. Its stability was verified through high speed centrifuge, acceleratedtest and long term experiment.(2)The analytical method of AIV was established throughultraviolet-visible spectrophotometer.(3)We evaluated the safety and antibacterial activitythrough acute toxicity test and broth dilution method respectively.(4)The high, middle andlow dose of AIV-NE, AIV and Tilmicosin solution was respectively dosed by drinking freelyto the chicken which were infected by Staphylococcus and the therapeutic efficacy in vivowas investigated.Result:(1) The mass fraction of the components in AIV-NE was Tween-8024%, ethanol12%, ethyl acetate4%, Acetylisovaleryltylosin1%, distilled water59%. AIV-NE was yellow,transparent, homogeneous and oil-in-water nanoemulsion. The shape of the nanoemulsiondrop was spherical and the average partical size was11.1nm with a polydispersity index of0.057. AIV-NE was stable after high speed centrifuge, accelerated test and long term exper-iment.(2)The result showed that the linearity of AIV was fine in the range of5～40μg·mL^-1,and the average recovery, relative standard deviation(RSD), RSD of the with-in-day precisionand the day-to-day precision were(99.71±0.853)%,0.855%,0.065%,0.087%, respectively.The analytical method of ultraviolet spectrophotometry (UV) had high recovery rate, goodrepetitiveness and precision which could offer a good method for determining the content ofAIV.(3)The median lethal dose(LD50) and95%confidence limit of AIV-NE were2425mg/kgand2204～2707mg/kg respectively. So its toxicity is low and it is safe by oral administration.(4)Antibacterial experiments in vitro showed that the MIC of AIV-NE on Enteropathog-enicE.coli, Staphylococcus, Salmonella, Pasteurella, Streptococcus agalactiae were16,2,8,4,8μg/mL respectively, its antibacterial effect was better than AIV and Tilmicosin solution.(5)The cure rate of AIV-NE in high, middle and low dose group was96.7%,93.3%and76.7%respectively, and effective rate was100%,96.7%and83.3%respectively. The cure rate and effective rate of AIV and Tilmicosin solution was66.7%,76.7%and60%,66.7%respectiv-ely.The effective number and cure number of AIV-NE high dose group has significant differe-nce with AIV-NE low dose group(P<0.05), and has extremely significant difference with AIVgroup and Tilmicosin group(P<0.01);and the AIV-NE middle dose group has significant diff-erence with AIV group(P<0.05),and has extremely significant difference with Tilmicosingroup (P<0.01). The average weight gained of high and middle group both has extremely sig-nificant difference with AIV and Tilmicosin group(P<0.01).Conclusion: The prepared AIV-NE has good stability, safety and better therapeutic effi-cacy, which would have wide prospect in clinical application.