Preparation Of Ceftiofur Sodium Nanoliposomes

Ceftiofur is the third generation of cephalosporin antibiotics specially used for animals.It has a wide antibacterial spectrum,strong antibacterial activity,fast absorption after administration,high bioavailability and long biological half-life,etc.,and is widely used in the treatment of cow mastitis.The aim of this study was to develop a safe and stable ceftiofur sodium nanoliposomes with strong antibacterial effect,high encapsulation rate,and evaluate its quality and safety to provide a theoretical basis for clinical treatment of dairy cow mastitis.1.Study on the preparation technology of ceftiofur sodium nanoliposomes.The content of ceftiofur sodium nanoliposomes was determined by ultraviolet spectrophotometry,and the encapsulation efficiency was determined by ultrafiltration centrifugation method.The standard curve was A=24.549C+0.1246,the average recovery was98.44%,and the RSDs were all less than 1%.The reverse evaporation and thin film dispersion process with anhydrous diethyl ether as cosolvent,phosphate buffer solution（PBS,p H6.3）as the hydration agent,with ceftiofur sodium and lecithin mass than,lecithin and cholesterol ratio,the volume of anhydrous diethyl ether and PBS is to examine factors,the encapsulation rate of evaluation indexes.Through the L₉（3⁴）orthogonal experiment design,the optimal formulation was obtained as follows:The membrane material ratio is 4:1,the drug lipid ratio is 1:5,and the organic phase and water phase ratio is 3:1.The liposome encapsulation efficiency was 61.8%±1.14%.2.Quality evaluation of ceftiofur sodium nanoliposomesThe morphology of the liposomes was observed by optical microscope and transmission electron microscope.The morphology of ceftiofur sodium liposomes was spherical vesicles without aggregation.The average particle size was 86.74 nm and the polydispersion index（PDI）was 0.23.The results of cumulative release rate calculated by in vitro drug release curve showed that ceftiofur sodium nanoliposomes had sustained release properties compared with ceftiofur sodium.Its stability was investigated by leakage rate and thermal stability test,and the results showed that its leakage rate was lower and stability was better at low temperature,and it should be stored in refrigerator for thermal instability.3.Safety evaluation and in vitro bacteriostatic test of ceftiofur sodium nanoliposomesThe safety of ceftiofur sodium nanoliposomes was evaluated by skin,muscle and mucosa irritation test,guinea pig systemic allergy test and acute toxicity test.The results showed that ceftiofur sodium nanoliposomes had no irritation to rabbit skin and muscle,but had slight irritation to mucosa.LD₅₀was 2077.23 mg/kg,belonging to low toxicity.The results showed that the antibacterial activity of ceftiofur sodium nanolipoplasts against streptococcus agalactiae,salmonella,staphylococcus aureus,escherichia coli and pasteuria were 4 times,2times,4 times,4 times and 4 times higher than that of ceftiofur sodium.