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

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HCS <strong>melt</strong>ing transition and 61.66 o C to <strong>the</strong> Tg <strong>of</strong> EC P7. This huge shift <strong>of</strong> <strong>the</strong> <strong>melt</strong>ing peak<strong>of</strong> HCS in HCS/ EC P7 is due to <strong>the</strong> lower gl<strong>as</strong>s transition temperature value compared tothat <strong>of</strong> EC N10. This also suggests that EC P7 would be more effective than EC N10 <strong>for</strong>processing HCS below <strong>the</strong> <strong>melt</strong>ing temperature. Fur<strong>the</strong>rmore, <strong>the</strong> extruded <strong>for</strong>mulationsexhibited a broad endo<strong>the</strong>rmic peak ranging from 47.83 to 49.19 o C indicating <strong>the</strong> presence<strong>of</strong> <strong>the</strong> drugs in <strong>the</strong>ir amorphous <strong>for</strong>ms. It h<strong>as</strong> been observed previously [23] that <strong>the</strong> position <strong>of</strong>shifted endo<strong>the</strong>rmic peak in <strong>the</strong> extruded <strong>for</strong>mulations is in between <strong>the</strong> <strong>the</strong>rmal transitions <strong>of</strong>amorphous drug and polymers.Fig. 8.2a: DSC transitions <strong>of</strong> pure polymers and drug.This <strong>the</strong>rmal phenomenon complements <strong>the</strong> <strong>for</strong>mation <strong>of</strong> solid dispersion <strong>of</strong> miscibleHCS in <strong>the</strong> amorphous polymer matrices [24] . Never<strong>the</strong>less, <strong>the</strong> characteristic peak <strong>of</strong> HCScannot be found in <strong>the</strong> heating curve <strong>of</strong> <strong>the</strong> extruded <strong>for</strong>mulations, indicating that <strong>the</strong> soildstate <strong>of</strong> <strong>the</strong> extruded <strong>for</strong>mulations are different having <strong>the</strong> HCS present in amorphous <strong>for</strong>mcompared to <strong>the</strong> drug/polymer physical mixtures.158 | P a g e

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