13.07.2015 Views

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

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

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

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

Table 5.2: Solubility parameters calculations summery <strong>for</strong> both drugs and polymersComp.pdhv∆∆R a(v)R a(v)(MPa 1/2 )(MPa 1/2 )(MPa 1/2 )(MPa 1/2 )(MPa 1/2 )CTZVRPCTZVRP(MPa 1/2 )(MPa 1/2 )CTZ 5.42 17.50 9.60 18.32 20.68 - - - -VRP 5.12 17.31 6.95 18.05 19.35 - - - -L100 0.41 19.31 12.03 19.31 22.75 2.07 3.4 5.33 5.12EZE 0.25 18.22 11.69 18.22 21.65 0.97 2.3 5.22 4.95Rav22( v2 v1) ( h2 h1)In this equation, p and d were observed to have similar <strong>the</strong>rmodynamic effects incontr<strong>as</strong>t to h. The two – dimensional approach can provide more accurate prediction <strong>of</strong> <strong>the</strong>drug – polymer miscibility by calculating <strong>the</strong> distance (R a(v) ) using <strong>the</strong> Pythagorean Theorem(24, 25). In this <strong>the</strong>ory two components are considered miscible when R a(v) ≤5.6MPa 1/2 . Inthis study it is obvious from Table 6.2 that even though <strong>the</strong> p values <strong>of</strong> <strong>the</strong> drug – polymercombinations differ significantly it does not affect <strong>the</strong> predicted miscibility.3.2 Scanning electron microscopy (SEM)Surface morphology w<strong>as</strong> examined by SEM <strong>for</strong> both <strong>the</strong> drug and extrudates (EXT).The extrudates containing L100 and EZE exhibited no drug crystals on <strong>the</strong> extrudate surfacewith CTZ (Fig. 5.1). Similarly, no VRP crystals were observed on <strong>the</strong> surface in all drug/polymer extrudates, indicating that VRP is also highly miscible with both anionicmethacrylate co-polymers in order to <strong>for</strong>m solid solutions. Thus, <strong>the</strong> SEM observations werealso quite sensitive to elucidate <strong>the</strong> presence <strong>of</strong> drug/polymer miscibility <strong>as</strong> well <strong>as</strong> <strong>the</strong><strong>for</strong>mation <strong>of</strong> drug/polymers amorphous solid dispersions by complementing <strong>the</strong> <strong>the</strong>rmalinvestigations.91 | P a g e

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!