Highly bioactive, bevacizumab-loaded, sustained-release PLGA/PCADK microspheres for intravitreal therapy in ocular...

Bevacizumab, a vascular endothelial growth factor (VEGF)-targeting drug, is widely used as an off-label therapeutic for age-related macular degeneration (AMD). To reduce the monthly administration frequency, this study investigated microspheres comprising a poly(d, l-lactide-co-glycolide)/poly(cyclohexane-1,4-diyl acetone dimethylene ketal) (PLGA/PCADK) blend that could be loaded with bevacizumab-dextran particles using solid-in-oil-in-water (S/O/W) emulsification. Control microspheres were also prepared through water-in-oil-in-water (W/O/W) emulsification. The structural stability of bevacizumab in the polymer monomers was analyzed using dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), size exclusion chromatography (SEC-HPLC), circular dichroism (CD) and fluorescence spectroscopy. Subsequently, microspheres were prepared and evaluated in terms of their morphology, encapsulation efficiency and release behavior. PLGA/PCADK microspheres prepared by the S/O/W method with <20% PCADK showed a smooth spherical structure with a uniform distribution of bevacizumab. The microspheres exhibited a release behavior comprising a slight initial burst and an increasing total release over 50 days both in vitro and in vivo. Additionally, the microspheres were well tolerated by ocular tissue. Finally, a chorioallantoic membrane (CAM) assay revealed that the bioactivity of bevacizumab was retained by PCADK. In conclusion, these results suggest the potential for bevacizumab-loaded PLGA/PCADK microspheres prepared by the S/O/W method as a means of intravitreal therapy for ocular diseases.