Studying the Crystal Growth of Selected Active Pharmaceutical Ingredients from Single- and Two-Component Systems above and below the Glass Transition Temperature

Abstract

In this paper, the crystal growth of three active pharmaceutical ingredients (APIs), griseofulvin, nifedipine, and naproxen, from the single component systems and the solid dispersions composed of APIs and acetylated maltose, has been investigated in a wide temperature range using optical microscopy. Additionally, complementary calorimetric and dielectric measurements have been carried out to characterize thermal properties and molecular dynamics of prepared samples. We found that close to the glass transition temperature (Tg), there is a sharp change in the T-dependence of the crystal growth rates (μcg) of APIs in four studied systems. Consequently, the activation barrier for the crystal growth (Ecg) calculated above and below this temperature differs significantly, indicating a change in the kinetics of this stage of crystallization. Furthermore, it was demonstrated that at T ≈ 1.25–1.3Tg, which may correspond to the crossover temperature (TB) related to the variation in molecular dynamics, a maximum in...