(306a) Crystallization Behaviour and Structural Characterization of Drug/Polymer Solid Dispersions

Drug/polymer solid dispersions have received extensive attention as a potential approach to increase the dissolution rate of the drug. However, there are still limitations that restrict the application of this technique for drug formulations. Understanding of the crystallization behavior for different drug/polymer systems and elucidation of the fundamental physicochemical processes that govern microstructural evolution are important, since the physicochemical properties and the dissolution mechanism are likely to be closely related to the solid dispersion phase behavior and microstructure. The purpose of this study is to fundamentally investigate the crystallization kinetics and microstructure evolution of drug/polyethylene glycol (drug/PEG) dispersions after solidification. Model drugs with different physicochemical properties will be employed. The crystallization behavior and the structure of the drug/PEG solid dispersions will be investigated mainly by simultaneous small-angle X-ray scattering/wide-angle X-ray scattering technique. The results indicated that the crystallization kinetics of PEG upon adding various drugs had been modified differently, likely to be related to the crystallization rate of the drug, solidification temperature, and solubility of drug in PEG. For the systems with amorphous drugs existing in the interlamellar regions of PEG, upon crystallization, the drugs migrated from the interlamellar regions of PEG to form crystals. The remaining amount of drugs in the interlamellar regions of PEG varied.