The Preparation of Core/Shell Structured Microsphere of Vancomycin/Rifampin and Evaluation of Bacteriostatic Effect In Vitro

In the treatment of chronic osteomyelitis, the local application of antibacterial drugs is the paramount method presently. In this work, we prepared core/shell structured microspheres of vancomycin (VAN)/rifampin (REP) by a modified method, namely coaxial electrohydrodynamic atomization. In group A, VAN and RFP were encapsulated in the core and shell respectively. And it was on the reverse in radial distribution in group B. The detection of encapsulation efficiency and in vitro release test were performed to confirm the feasibility of the drug-loaded core/shell structured microspheres. In addition, the evaluation on antibacterial effect of core/shell structured microsphere of VAN/RFP on methicillin-resistant Staphylococcus aureus (MRSA) in vitro was carried out. The release patterns of the two groups are significantly different. The release of VAN and RFP from group A samples was relatively straightforward, namely simultaneous release, and last at least 27 days, whereas the release of drugs from group B microspheres was in a programmed release manner. Moreover, all the extracted drug solution from VAN and RFP microspheres in different time intervals showed obvious antiseptic effects on MRSA. In conclusion, core/shell structured microspheres with VAN in the core and RFP in the shell can achieve long-term and simultaneous release, which have excellent antibacterial ability against MRSA. These findings presented the advantages and feasibility of this kind of core/shell structured microspheres in treating chronic osteomyelitis.