Development of photostable gastro retentive formulation for nifedipine using low-density polypropylene microporous particles.

The aim of this study was to develop photostable gastro retentive formulation for nifedipine loading into low-density polypropylene microporous particles (Accurel MP 1000®) by a solvent evaporation technique using the 3² factorial design. Yield, drug loading, surface topography, thermal properties, crystal characteristics, photostability and in vitro drug release were studied. Optimized microparticles formulated into a capsule were evaluated for the dissolution study and compared with marketed formulation. Higher values of T(₅₀%), time required for 50% degradation of drug with threefold and 1.5-fold decrease in degradation rate constant (K) under UV and fluorescent lamp were observed for the microparticles, respectively, as compared to pure nifedipine indicated remarkable improved photostability. Microparticles showed good floating ability in 0.1N HCl with initial burst release (16-29%) followed by the zero-order drug release up to 8 h. The capsule formulation followed the ideal modified release pattern.