Synthesis and characterization of novel poly(sebacic anhydride-co-Pluronic F68/F127) biopolymeric microspheres for the controlled release of nifedipine

Amphiphilic block copolymers composed of prepoly(sebacic anhydride) and Pluronic-F68/F127 have been synthesized in different molar compositions via melt-polycondensation reaction. Poly(sebacic anhydride-co-PLF68/PLF127) thus formed was characterized by Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC) and nuclear magnetic resonance spectroscopic (NMR) techniques. The amphiphilic block copolymers were used to prepare microspheres and to encapsulate nifedipine (NFD) by the solvent evaporation technique. Differential scanning calorimetry (DSC) was used to confirm the incorporation of Pluronic into polyanhydrides, while X-ray diffraction (XRD) was performed on the drug-loaded microspheres to investigate the crystalline nature of the drug after encapsulation. Scanning electron micrograph (SEM) pictures indicated spherical nature of the microspheres. Microspheres obtained were in the size range of 10–50 μm as measured by the laser particle size analyzer. In vitro release studies of NFD from poly(sebacic anhydride-co-Pluronic-F68/F127) microspheres performed in pH 7.4 phosphate buffer indicated sustained release rates of NFD at higher amounts of Pluronic in polyanhydride copolymers; there was no significant difference obtained between the release patterns of NFD from Pluronic-F68 and Pluronic-F127 copolyanhydride microspheres when same amount of Pluronics were used.