RESUMEN
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.
Asunto(s)
Bloqueadores de los Canales de Calcio/administración & dosificación , Preparaciones de Acción Retardada/química , Nifedipino/administración & dosificación , Polipropilenos/química , Tracto Gastrointestinal Superior/metabolismo , Bloqueadores de los Canales de Calcio/química , Bloqueadores de los Canales de Calcio/metabolismo , Cápsulas/química , Composición de Medicamentos , Estabilidad de Medicamentos , Humanos , Nifedipino/química , Nifedipino/metabolismo , Fotólisis , Porosidad , Solubilidad , Rayos UltravioletaRESUMEN
The solid-state properties and dissolution behaviour of lamotrigine in its inclusion complex with beta-cyclodextrin (betaCD) and solid dispersions with polyvinylpyrrolidone K30 (PVP K30) and polyethyleneglycol 6000 were investigated. The phase solubility profile of lamotrigine with betaCD was classified as AL-type, indicating formation of a 1:1 stoichiometry inclusion complex, with a stability constant of 369.96+/-2.26 M(-1). Solvent evaporation and kneading methods were used to prepare solid dispersions and inclusion complexes, respectively. The interaction of lamotrigine with these hydrophilic carriers was evaluated by powder X-ray diffractometry, Fourier transform infrared spectroscopy and differential scanning calorimetry. These studies revealed that the drug was no longer present in crystalline state but was converted to an amorphous form. Among the binary systems tested, PVP K30 (1:5) showed greatest enhancement of the solubility and dissolution of lamotrigine.
