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

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PRP w<strong>as</strong> determined at 34.74 o C. Overall, DSC analysis confirmed <strong>the</strong> creation <strong>of</strong> moleculardispersions <strong>for</strong> all extruded <strong>for</strong>mulations.Fig. 6.2b: DSC <strong>the</strong>rmograms <strong>of</strong> DPD/L100 (PM), DPD/L100 (EXT), DPD/L100-55 (PM)and DPD/L100-55 (EXT).3.4 X-ray powder diffraction (XRPD)To examine PRP and DPD crystalline state diffractograms <strong>of</strong> pure drugs, <strong>the</strong> drug –polymer extrudates and <strong>the</strong>ir binary physical mixtures were recorded by X–ray powderdiffraction analysis. As can be seen from Fig. 5.3, <strong>the</strong> diffractograms <strong>of</strong> pure PRP and DPDpresented distinct peaks at 8.38 o , 9.71 o , 12.51 o , 16.72 o , 19.49 o , 21.26 o , 22.06 o , 23.59 o , 25.07 o ,27.07 o -39.07 o 2 and 10.41 o , 12.39 o , 18.61 o , 20.34 o , 22.03 o , 24.87 o , 26.55 o , 31.45 o 2,respectively. As shown in Fig. 6.3 <strong>the</strong> PM <strong>of</strong> all PRP <strong>for</strong>mulations presented identical peaksat lower intensities suggesting that both drugs retained <strong>the</strong>ir crystallinity at loads <strong>of</strong> 10%. Incontr<strong>as</strong>t no distinct intensity peaks were observed in <strong>the</strong> diffractograms <strong>of</strong> <strong>the</strong> extruded<strong>for</strong>mulations. The absence <strong>of</strong> PRP and DPD intensity peaks indicates <strong>the</strong> <strong>for</strong>mation <strong>of</strong> a soliddispersion where <strong>the</strong> drugs are present in amorphous [22] state or molecularly dispersed into<strong>the</strong> polymer matrix.112 | P a g e

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