Wh. Chuo et al., INVESTIGATION OF THE INTERNAL STRUCTURE AND RELEASE BEHAVIOR OF TABLETS COMPRESSED BY NIFEDIPINE-LOADED ALBUMIN MICROSPHERES, Die Pharmazie, 53(2), 1998, pp. 104-109
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.