Preparation of Diclofenac Sodium Composite Microparticles with Improved Initial Release Property

The aim of this study is the evaluation of the effect of microencapsulation of nanoparticles in composite microparticles on the reduction of burst release. Microparticles (simple and composite) and nanoparticles were prepared by using water-in-oil-in-water (W/O1/W2 double-emulsion solvent diffusion/evaporation method), using different drug/polymer ratios. For preparation of the composite microparticle, nanoparticle suspension was used as the internal phase. In this investigation, the microparicle, nanoparticle and composite microparticle formulations prepared were characterized by loading efficiency, yield, particle size, zeta potential, XRD (X-ray Diffractometry), FTIR (Fourier Transform Infrared Spectroscopy), DSC (Differential Scanning Calormetry) and drug release. The best drug of the polymer ratio in the microparticle and nanoparticle were F3 (0.4:1) and NP1 (0.1:1), which showed 26.89% and 9.07% of entrapment, loading efficiency 94.2 %, 99.44% and mean particle size 13.114 m and 756 nm, respectively. The drug loading microparticle, COM3 (nanosuspension with 0.2.:1 drug/polymer ratio), showed 28.56% of entrapment, loading efficiency 99.96% and mean particle size 13.013 m. The burst was significantly lower with composite microparticles and may be explained by the slower di usion of the drugs through the double polymeric wall formed by the nanoparticle matrix, followed by another di usion step through the microparticle polymeric wall.