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

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Fig. 8.1: SEM images <strong>of</strong> [(a), (b)] HCS/ EC N10 (magnification x500 and 10K, respectively)and [(c), (d)] HCS/EC P7 extruded <strong>for</strong>mulations (magnification x500 and 10K, respectively).3.3 Differential scanning calorimetric (DSC)Differential scanning calorimetry (DSC) w<strong>as</strong> used to analyse <strong>the</strong> solid state <strong>of</strong> pureAPI, polymers, <strong>the</strong>ir physical mixtures (PM) and active extruded <strong>for</strong>mulations (EXT). Theoverall findings from DSC results are summarized in Figs 8.2a and b. The DSC scan <strong>of</strong> pureHCS in Fig. 8.2a showed an endo<strong>the</strong>rmic transition corresponding to its <strong>melt</strong>ing point [23] at226.12 o C (H = 114.92 J/g, peak height 17.80 mW) with an onset at 223.82 o C. Similarly, <strong>the</strong>pure polymers showed Tg at 133.01 o C corresponding to Tg <strong>of</strong> EC N10 and 117.61 o Ccorresponding to Tg <strong>of</strong> EC P7, respectively (Fig. 8.2a). Even though, all binary physicaldrugs/polymer blends exhibit endo<strong>the</strong>rmic peaks (Fig 8.2b) corresponding to <strong>the</strong> initialsubstances at slightly shifted temperatures indicating <strong>the</strong> drug existence in its crystalline<strong>for</strong>m, <strong>the</strong> <strong>melt</strong>ing peaks were absent in all extruded <strong>for</strong>mulations. In <strong>the</strong> drug/polymerphysical mixture (PM) <strong>of</strong> HCS/ EC N10 <strong>for</strong>mulation, two endo<strong>the</strong>rmic peaks were visible(Fig 8.2b), one at 202.87 o C (H= 5.38 J/g) corresponding to <strong>the</strong> <strong>melt</strong>ing peak <strong>of</strong> crystallineHCS present in <strong>the</strong> mixture and ano<strong>the</strong>r one at lower temperature range at 72.27 o Ccorresponding to <strong>the</strong> Tg <strong>of</strong> EC N10. Similar transitions were observed in <strong>the</strong> HCS/EC P7system <strong>as</strong> well where <strong>the</strong> endo<strong>the</strong>rmic peak at 185.86 o C (H= 13.97 J/g) corresponds to <strong>the</strong>157 | P a g e

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