Development of nanoparticles-in-microparticles system for improved local retention after intra-articular injection

AbstractTo increase the intra-articular (IA) retention time of osteoarthritis drugs in the synovial cavity and slow down the burst release of microspheres (MPs), we prepared a novel drug delivery system named nanoparticles-in-microspheres (NiMs). The system was constructed by dispersing the brucine-loaded nanoparticle, which was prepared by an emulsification method in the MPs. The NiMs were characterized by scanning electron microscope, Fourier transform infrared spectra and differential scanning calorimetry. After investigating the biocompatibility with synovium of NiMs in rats, the pharmacokinetics was studied and FX-imaging was used to visualize the transmission of nanoparticles after IA administration in rats. From the results, we know that the NiMs were spherical, there was no chemical bond between the drug and the polymer, and the drug was dispersed in the polymer in an amorphous form. Compared with MPs (41%), the burst release of NiMs could be slowed down to 9%. After that, the drug was released fr...