P

Permeation of drug molecules through the solid polymer, which may be acting as a drug depot, is a function of the solubility of the drug in the polymer as

Addition of inorganic fillers in which the

Addition of inorganic fillers in which the

amorphous; the total volume fraction of crystalline regions, 0c, can be calculated from measurements of density.

drug is insoluble alters the overall solubility of the drug in the polymer and hence alters the permeation characteristics. The equation for overall solubility (5) is given by

where f refers to filler and p to polymer. Thus, when 5f 2 0, as happens when inorganic fillers such as zinc oxide are employed, an obstruction-type equation may be written:

0 0

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