Thermal analysis of glassy pharmaceuticals

The glassy state of many solids is achieved when the solids are heated above their melting point (T,,,) and rapidly cooled through it. Glassy solids are usually brittle and transparent. The glassy state can be identified through the glass transition temperature (T,) using differential thermal analysis (DTA), differential scanning calorimetry (DSC), thermomechanical analysis (TMA), dynamic thermomechanical analysis (dTMA), or torsional braid analysis (TBA). Pulsed NMR spectroscopy is also a method used for confirmation of the glassy state. In this paper most attention is devoted to the low-molecular glassy pharmaceuticals. The influence of cooling rate during glass preparation on TE, the influence of heating rate on Tg, the influence of heating rate on crystallization, and the influence of annealing on the glassy state are reviewed and discussed with reference to the recently published original research papers. The possibility that glass dispersion systems may be used to improve the stability and useability of glassy pharmaceuticals is also included.