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

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Eq. (6) is a Korsmeyer–Pepp<strong>as</strong> model equation concerning <strong>the</strong> diffusion mechanism,and it h<strong>as</strong> been evaluated concerning pharmaceutical preparations <strong>of</strong> many matrix types.When both terms <strong>of</strong> Eq. (8.6) are converted to logarithms, <strong>the</strong> equation becomes ln F = lnK4+ n ln t, and <strong>the</strong> slope n can be determined by plotting <strong>the</strong> logarithm <strong>of</strong> <strong>the</strong> rele<strong>as</strong>e rate against<strong>the</strong> logarithm <strong>of</strong> time (Fig. 8.5d).Fig. 8.5d: A plot <strong>of</strong> <strong>the</strong> logarithm <strong>of</strong> HCS rele<strong>as</strong>ed <strong>as</strong> a function <strong>of</strong> <strong>the</strong> logarithm <strong>of</strong> timeaccording to <strong>the</strong> Korsmeyer–Pepp<strong>as</strong> model. Each result shows <strong>the</strong> mean±S.D. (n=3).The exponent (n) determined by this equation suggests that both <strong>the</strong> uncoated andcoated tablets show Fick‘s diffusion when n = 0.40-0.45 (<strong>for</strong> tablets). It h<strong>as</strong> been reportedthat a non-Fickian type rele<strong>as</strong>e which is also known <strong>as</strong> anomalous transport occurs only when0.45 < n < 0.89, c<strong>as</strong>e-II transport can be observed when n = 0.89, and super c<strong>as</strong>e-II transport166 | P a g e

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