Analysis of Glass Transition Temperatures in Indomethacin/Polymer Mixtures

While drugs are typically created, stored, and administered in the more stable crystalline state, there is interest in industrial settings to stabilize amorphous pharmaceuticals to overcome bioavailability constraints. The stability of an amorphous pharmaceutical is directly tied to its β-glass transition, although its detection is often difficult. Terahertz time-domain spectroscopy (THz-TDS) is one technique that can be used to determine this transition as well as the more commonly observed α-glass transition in the same experiment. While both transitions can be observed, the relationship between them has yet to be analysed in detail. Indomethacin is an extensively studied anti-inflammatory, providing a benchmark sample for a glass transition analysis with terahertz time-domain spectroscopy. By mixing indomethacin at varying ratios in polymeric matrices, its amorphous stability observed through changing glass transitions can be observed, revealing trends in the THz-TDS results that directly relate to the potential energy surface of the system. This insight can have a lasting impact on the future creation of amorphous pharmaceuticals.