Rheological study and characterization of acetaminophen and poly (ethylene) oxide for hot-melt extrusion process

Solid dispersions made from mixing polymers and drug have caught a lot interest in recent years. One major technical barrier limiting broader applications of solid dispersions is the lack of drug's solubility data in polymer matrix. Furthermore, there is no standard or widely accepted method for the testing of drug's solubility. Zhang et. al [1] developed a novel method using Differential Scanning Calorimeter (DSC) recently. However, it requires tedious and delicate experimental work. Therefore, a new method via rheological characterization is explored in our laboratory. The steady (from both oscillatory and capillary rheometer) and dynamic (oscillatory rheometer) viscosities of the drug-polymer system are measured for different drug concentrations at various temperatures. The rheological results presented not only can be utilized for process optimization and material characterization, such as molecular weight determination, but also provides valuable information on the drug's solubility in polymeric excipients.