ËÄÉ«AV

Crystallization tendencies, thermal anal. [i.e. glass transition temperature (Tg)], crystallinity, and m.p. depression, along with theor. calculations such as solubility parameter, of five different drugs [i.e. curcumin (CUR), indomethacin (IND), flutamide (FLU), dipyridamole (DIP), and griseofulvin (GRI)] in the absence and presence of four different polymers in various drug-polymer ratios were determined and analyzed. Phys. states of the drug in the solid dispersions (SDs) and their stability were characterized by X-ray diffraction and modulated differential scanning calorimetry. IR (IR) and Raman were used in selected systems (i.e. CUR, DIP, and GRI systems) to explore the role of drug-polymer interactions in the amorphization of SDs. The crystallization tendencies of pure drugs were categorized as low (CUR, IND), moderate (FLU), and high (DIP, GRI). In the presence of selected polymers, the crystallization tendency of the drugs changed, though a high polymer concentration was required for high crystallization-tendency drugs [i.e. DIP and GRI (>50% weight/weight)]. Polymers showing a greater effect on the crystallization tendency of drugs were found to have higher drug-polymer miscibility and stronger mol. interactions. Drug-polymer systems selected from the investigation of phys. mixtures formed stable amorphous solid dispersions (ASD). Furthermore, the rank order of the crystallization tendency of drug-polymer systems correlated well with those on miscibility and mol. interactions. Those rank orders also correlated well with the stability of prepared/reported SDs. Hence, the developed approach has significant potential to be a rational screening method for the development of amorphous SDs.