RESUMO
We prepared moxifloxacin (MXF) loaded nanoparticles by nano-precipitation/self-assembly method, then compared the antibacterial activity of MXF and MXF loaded nanoparticles, and investigated the antibacterial mechanism of MXF loaded nanoparticles against Pseudomonas aeruginosa in vitro. The physicochemical properties such as particle size and zeta potential were investigated by laser particle size analyzer. The in vitro release characteristics were investigated by high performance liquid chromatography (HPLC). The effect of nanoparticles on HBE cells viability was investigated by CCK-8 assay. In addition, the in vitro antibacterial activity was investigated by minimum inhibitory concentration (MIC) assay, biofilm formation assays and transmission electron microscope (TEM) observation, then the antibacterial mechanism was initially explored. The particle size measurement showed that the nanoparticles had a size of 332.5 ± 2.7 nm, a polymer dispersion index (PDI) of 0.125 ± 0.053, a zeta potential of -24.3 ± 1.7 mV, and a uniform particle size distribution, drug loading content was (6.02 ± 1.27) %, encapsulation efficiency was (16.69 ± 1.17) %. The TEM results show that the nanoparticles have a spheroidal structure, and the particle size and distribution are consistent with the particle size measurement results. The nanoparticles can be effectively and rapidly released in phosphate buffer saline (PBS), releasing about 70% in 24 h, and releasing 87% in 72 h, and almost completely releasing the MXF at 120 h. At the same time, compared with moxifloxacin free drug, its MIC value is 8 μg·mL-1, which is 1/2 of MXF solution, and can significantly inhibit the formation of bacterial biofilms. It has well antibacterial activity in vitro and can be targeted to the surface of bacteria to exert its efficacy and improve the antibacterial effect. The moxifloxacin nanoparticles prepared in this study has a uniform particle size distribution, well drug release performance and antibacterial effect, and provides new ideas and strategies for the treatment of bacterial lung infection and the development of new antibacterial nanoformulations.
RESUMO
OBJECTIVE： To establish the method for simultaneous determination of clopidogrel （CLP）， its intermediate metabolite （2-O-CLP）， inactive metabolite （CLPCA） and active metabolite （CLPTM） in human plasma. METHODS： Totally 90 patients diagnosed as stroke were selected from the First Affiliated Hospital of Army Medical University. They were given one CLP tablet （75 mg/tablet） orally on an empty stomach in the morning. Blood samples were collected 2 h after taking the tablet. CLPTM- D was formed by derivation of CLPTM with 2-bromo-3’-methoxyacetophenone and extracted by precipitation of acetonitrile protein together with the other three substances to be measured. LC-MS/MS method was adopted. The determination was performed on Agilent poroshell 120 EC-C18 column with mobile phase consisted of acetonitrile （0.1％ formic acid） and water （0.1％ formic acid） （90 ∶ 10， V/V）. The quantitation analysis was performed using multiple reaction monitoring at the specific ion transitions of m/z 308.1→198.1 （CLPCA）， 322.3→212.0 （CLP）， 338.3→155.0 （2-O-CLP）， 504.4→354.1 （CLPTM-D） and 264.0→154.1 （ticlopidine， internal standard）， respectively. RESULTS： The retention time of CLPCA， CLP， 2-O-CLP， CLPTM-D and internal standard were 2.01， 3.32， 2.83， 2.68， 1.87 min， respectively. The linear range of CLPCA， CLP， 2-O-CLP and CLPTM-D were 100-10 000， 0.2-20， 0.3-30， 0.5-50 ng/mL （all r≥0.999 5）. The intra-day and inter-day RSD were all less than 9.5％ （n＝5）. Accuracy ranged from 93.5％-98.9％ （n＝5）， and extraction recovery was from 85.4％ to 95.9％ （n＝5）. The matrix effect ranged from 2.7％-6.2％ （n＝5）. In stability tests （storing at －80 ℃ for 3 months， 3 freeze-thaw cycles， storing at 4 ℃ for 8 h）， RE of CLP， CLPCA and CLPTM-D were all lower than 10.0％ （n＝5）. CONCLUSIONS： Established LC-MS/MS method has the advantages of high specificity， accuracy and reliability， and can be used to detect the concentration of CLP and its three metabolites in human plasma.