| Cefquinome Sulfate (CS) is a fourth-generation cephalosporin, which has been developed solely for veterinary use. It shows potent antibacterial activity against a broad spectrum of bacterial species. It is widely used in the clinical treatment of pigs and cattle respiratory infections by foreign. However, its effective blood concentration of short duration, only repeated administration to achieve effective therapeutic concentrations. And the repeated administration could easily lead to the slow drug metabolism, increase in food of animal drug residues, is not conducive to the growth of animal and human health hazards. In addition, the instability of Cefquinome Sulfate greatly limits its clinical application. In order to exploit new sustained-release and lung targeting formulations of Cefquinome Sulfate, the solid dispersion combined with the effervescent hydration method be used to prepare. And their physical and chemical properties, in vitro release, the pharmacokinetics in rabbits and tissue distribution in mice to inspect. The main findings are as follow:For design prescription and determination the encapsulation efficiency and drug loading of Cefquinome Sulfate liposome, an RP-HPLC method for the determination of Cefquinome Sulfate liposome was first established in this test. The standard curve was A=17253C-3148.2 (r2= 0.9998), and in concentration of 0.25-64μg/mL have a good linear relationship. The average recovery rate was 99.16% and the average method recovery was 100.24%, intra-day precision and inter-day precision <5%. It had showed that the method in line with the requirements of the HPLC content determination. In addition, the saturated solubility of Cefquinome Sulfate in pH7.0 PBS was 10.38±0.09 mg/mL and the lipid-water partition coefficient was 0.434±0.01.In order to achieve a high encapsulation efficiency and morphology preferably liposome, the test has used a thin film dispersion method, ethanol injection method, a mechanical homogenizer method, reverse phase evaporation method, pH gradient method, and the solid dispersion combined with the effervescent hydration method to prepare Cefquinome Sulfate liposome. Found that the solid dispersion combined with the effervescent hydration method was the best way. Single-factor test was adopted to investigate the major influencing factors on entrapment efficiency in the solid dispersion combined with the effervescent hydration method. Meanwhile, orthogonal design duplication test was used to optimize the preparation process. As a result, the best prescription and preparation were:Soybean lecithin and cholesterol mass ratio was 2:1, the amount of Tween-80 was 90 mg, drug-SPC ratio was 1:10, and the citric acid / sodium bicarbonate used in an amount of 600/120mg. In accordance with the best process to prepare Cefquinome Sulfate liposome, the liposome encapsulation efficiency was 55.17± 0.44% and he average drug loading was 2.70±0.02.The quality of Cefquinome Sulfate liposome prepared by the solid dispersion combined with the effervescent hydration method was overall evaluated by means of physical and chemical properties and in vitro drug release. The appearance of the liposomes as a uniform milky-white suspension, the mean particle size was 203±5 nm, and the polydispersity index was 0.36. Stability test found the Cefquinome Sulfate liposome was unstable in humid environment and light environment. It should be stored in dry and dark conditions. And hemolysis test found the liposome has no hemolytic reaction. The in vitro drug release of Cefquinome Sulfate liposome test found that Cefquinome Sulfate solution released much faster and ARP was 92.48% within 8 h. By contrast, Cefquinome Sulfate released much slower from liposome with ARP of less than 51.78% during the same time periods and the ARP was 79.14% after 24h.This indicates that the Cefquinome Sulfate liposome have a sustained release effect. Cefquinome Sulfate liposomes preferable in accordance with Weibull equation, that is the first part of the rapid release, then partially released slower.The test examines the pharmacokinetics investigation of Cefquinome Sulfate solution group and liposome group in rabbits. And found that a two-compartment model with a weighting coefficient of 1/C2 presented the best fit to the drug concentration-time curves of the two preparations. The pharmacokinetic equation were C(t)=184.49e-35.73t+23.644e-0.571t+0.697e-0.079t and C(t)=37.648e-2.165t+42.066e-0.497t+4.537e-0.042,espectively. The pharmacokinetic parameters for the solution and liposomal formulations were measured as follows: t1/2α were (1.214±0.135) h and (1.395±0.113) h, t1/2β were (8.752±0.846) h and (16.503±1.275) h, AUC(0-24)were (49.582±9.173) (mg-h)/L and (138.727±11.034) (mg·h)/L, CL/F were (0.357±0.015) L/(h·kg) and (0.127±0.012) L/(h·kg), MRT(0-24) were (2.68±0.229) h and (5.945±0.479) h, respectively. The main pharmacokinetic parameters also indicated that in the plasma drug concentration of liposome group, the values of t1/2β AUC, MRT and CL/F markedly increased by about 1.89-fold(P<0.05),2.8-fold(P<0.01),2.2-fold(P<0.01) and 0.36fold,respectively,in comparison to that of the solution group. Compared with the solution group, the t1/2β of liposome group extension 8h and the AUC increased by 89.145mg·h·L-1. All these results demonstrated that CS making into liposome formulation had palpable characteristics of sustained-release, as a result of prolonging the duration of drug concentration, reducing drug given bits and enhancing therapeutic efficiency.In the tissue distribution studies of mice, the relative uptake rate (Re),the targeting coefficient (TCe), targeting efficiency (Te) and peak concentration (Ce) four indicators were used to examine the Cefquinome Sulfate liposome targeting. The result indicated that the cefquinome sulfate liposome relative uptake in the lungs was 8.86, the total targeted coefficient was 0.35, the bulk drugs targeting efficiencywas5.70 and the peak plasma concentration ratio was 1.61. Four indicators show the liposomal formulations have better lung targeting and three indicators show that the liposome preparation has good liver targeting. The Cefquinome Sulfate as the primary drug for the treatment of pork, beef in respiratory tract infections, prepared liposome of pulmonary targeting have great significance for the clinical use of drugs.The test results show that the preparation process of cefquinome sulfate liposome was feasible, simple and convenient, and quality control. The physical and chemical indicators are in line with the requirements of liposome preparations.The preparation has a preferable sustained-release and lung targeting, is conducive to extend the cycle time of the drug in the body, improve the drug levels of the target site to enhance the therapeutic efficacy and reduce the frequency of administration and dose reached the pilot study intended purpose. |
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