ABSTRACT
OBJECTIVE: To investigate the influencing mechanism of the particle size of hydroxypropyl methylcellulose (HPMC) on the release behavior of nifedipine from a sustained-release tablet system based on the compaction properties of HPMC. METHODS: The compaction properties of HPMC K4M of different particle sizes were determined. Hydrophilic matrix sustained-release tablets were prepared using nifedipine as the active ingredient and HPMC K4M as a hydrophilic matrix former. The effect of compaction properties of HPMC K4M on the porosity, release, and other properties of nifedipine hydrophilic matrix sustained-release tablets were also studied. RESULTS: The decrease of the particle size of HPMC K4M resulted in higher bulk density, tap density, compressibility index, and tensile strength and smaller elastic recovery of HPMC K4M, which all led to the decrease of thickness and porosity and the increase of HPMC concentration per unit volume of nifedipine hydrophilic matrix sustained-release tablets. These factors resulted in faster gelation rate of nifedipine sustained-release tablets and decreased water ingress and polymer swelling, so the release of nifedipine from the delivery system was prolonged. CONCLUSION: The obviously different compaction properties of HPMC of different particle sizes influence the porosity and gelation rate and then the release of hydrophilic matrix nifedipine sustained-release tablets.