INVESTIGATION OF THE INTERNAL STRUCTURE AND RELEASE BEHAVIOR OF TABLETS COMPRESSED BY NIFEDIPINE-LOADED ALBUMIN MICROSPHERES

The aim of this study was to investigate the release characteristics o f tableted nifedipine-loaded albumin microspheres and relate the compr ession behavior to untableted microspheres. The Heckel equation and Ka wakita equation which are the most frequently used for obtaining pract ical data concerning the densification manner of materials compressed were used to evaluate the compaction properties, and four different th eoretical models, that is, zero-order, first-order, spherical matrix a nd a planar matrix model, were analysed for the kinetics of nifedipine released from tableted microspheres. The effect of excipient (Era-Tab (R) and Avicel PH101(R)) on the release of tableted microspheres was a nother focal paint in the present study. The results revealed that the compaction behavior showed a good relationship to the concentration o f the crosslinking agent glutaraldehyde; microspheres cross-linked by smaller amounts of glutaraldehyde exhibited better compaction behavior . Furthermore, Era-Tab(R) showed a protective effect for microspheres under compaction process which was better than Avicel PH101(R). Micros pheres prepared with the least amount of glutaraldehyde compressed acc ompanied with Era-Tab(R) maintain a similar release rate and the same spherical matrix release model during the compression process, while A vicel PH101(R) did not exhibit this phenomenon.