Preparation,Characterization And Evaluation In Vivo/in Vitro Of Cefalonium Nanosuspension Lyophilized Powder

The cefalonium is one of cephalosporins developed by Schering-Plow special for animals,which is mainly used for the prevention and treatment of mast itis in dairy cows.At present,the cefalonium intramammary infusion?Cepravin?Dry Cow?has been registered in the EU and the British Commo nwealth countries,New Zealand,Australia and Japan,but are not available in C hinese markets.In this paper,the cefalonium nanosuspension lyophilized powder was developed by high pressure homogenization method,and its characterization and evaluation in vitro/in vivo were carried out.The cefalonium nanosuspension lyophilized powder was prepared by high pressure homogenization and freeze-drying.The single factor test and orthogonal design were used for the optimization of prescription and conditions.The particle size and morphology were characterized by laser nanometer particle sizer and transmission electron microscopy?TEM?.In result,the content of cefalonium nanosuspension lyophilized podwer determined by high performance liquid chromatography?HPLC?was 98.10%,and the related substances were in accordance with the requirements.The mean particle size of cefalonium nanosuspension lyophilized power was 623.20 nm,with polydisperse index of 0.26.TEM images showed regular morphology and uniform distribution.After the high temperature,high humidity,strong light test and accelerated test,the appearance of the sample color,content,and related substances and other indicators did not change significantly,indicating abetter stability of the formulation.The minimum inhibitory concentration of cefalonium nanosuspension lyophilized powder and raw drugs was determined by agar dilution method.The antibacterial activities of cefalonium nanosuspension lyophilized podwer and raw drug were determined against Staphylococcus aureus,E.coli,and Streptococcus by agar diffusion method.The MIC of cefalonium nanosuspension lyophilized power were 0.05⁰.20?g/mL,0.78¹00?g/mL,0.006⁰.012?g/mL,and the MIC of raw drugs were 0.10⁰.20?g/mL,1.56¹00?g/mL,0.006¹.560?g/mL,respectively,indicating that cefalonium nanosuspension lyophilized powders showed a better antibacterial activity in vitro.The safety evaluation was carried out by rabbit skin irritation test,vaginal irritation test and active skin allergic test in guinea pigs.The results showed that cefalonium nanosuspension lyophilized powder had no irritation to the skin and vaginal mucosa of rabbits,and there was no obvious skin allergic reaction to guinea pigs,which indicated that cefalonium nanosuspension lyophilized powder had good safety.Ten healthy weaning female rabbits were randomly divided into two groups?n=5?.The cefalonium nanosuspension lyophilized powder and common suspension was administered at 60mg single dose through intramammary infusion.The plasma drug concentration were tested by high performance liquid chromatography?HPLC?.The non-compartmental model of WinNonlin5.2.1 was used to fit the drug-time curve and the related pharmacokinetic parameters were calculated.The main pharmacokinetic parameters of cefalonium nanosuspension lyophilized powder:t_1/2 was 88.70±13.25 h,T_max was 10.80±1.09 h,C_max was 345.04±53.98 ng/mL,AUC_0-168h was 1024.04±4509.96 ng·h/mL,MRT_0-168h was 37.61±12.86 h,and Kel was 0.008±0.001h^-1.The main pharmacokinetic parameters of common suspension:t_1/2 was 68.39±17.36 h,T_max was 10.40±0.89 h,C_max was 332.80±104.87 ng/mL,AUC_0-168h was 23775.73±7313.54 ng·h/mL,MRT_0-168h was70.03±1.83h,and Kel was 0.011±0.003h^-1.Pharmacokinetics of the nanosuspension lyophilized powder were altered relative to the common suspension.AUC _0-168h was reduced and t_1/2 was much prolonged,indicating less absorbed into the blood and a certain sustained release effect.