Development of hot-melt extrusion as a novel technique for the ...

grades (3.5-5.5 g water/g polymer) and in combination with the smaller particle size, displayfaster disintegration times.Fig. 3.5(a-d) depicts the tablet hardness versus the compaction force at varioussuperdisintegrant concentrations and compaction forces. It can be seen that the hardnessincreased with concentrations up to 5% (wt/wt) for all superdisintegrants. When highdisintegrant concentrations (>10% wt/wt) were used, the tablets became softer and thehardness decreased (except CL 20% w/w) as a result of modest compressibility. Anotherinteresting observation for all disintegrants is that the hardness increased with an increase inthe applied compaction force. The results obtained from friability studies indicate dissimilarbehaviour for each disintegrant. For instance, Kollidon CL and Vivasol at 2-10% wt/wtdisplayed no impact of disintegrant level at 8-12 kN compaction forces but displayed highfriability at concentrations of 20% w/w. On the other hand, XL and CL - SF showed very lowfriability at 2% levels and a slight increase from 5-20% levels. In the case of XL10, theoptimum friability was observed at 10% w/w levels.The rapid disintegration times described above are also related to tablet porosity as can beseen in Table 2. High porosity is a critical ODT parameter because it facilitates liquidpenetration into the tablet and results in faster disintegration. The estimated porosities for allODT formulations were quite high, varying from approximately 0.13-0.16 without howevercompromising tablet mechanical properties. The hardness and friability studies demonstratedacceptable mechanical properties as mentioned above (Hardness about 7 Kp, friability