Theory for the structural relaxation and self-diffusion of amorphous indomethacin under various thermodynamic...

Indomethacin has grabbed considerable attention since the 1960s due to its special analgesic, antipyretic, and anti-inflammatory abilities. However, the glassy dynamics of this nonselective cyclooxygenase inhibitor remains poorly understood, particularly at low temperatures and high pressures. Here, we develop a theory based on the elastically collective nonlinear Langevin equation to shed light on the relaxation and diffusion behaviors of indomethacin in supercooled, vitrified, and compressed states. To optimize computational processes, we consider the influences of local interactions, collective excitations, and density fluctuations via hard-sphere approximations. Finite-temperature, -pressure, and -time effects are included by analyzing volumetric changes during cooling, squeezing, and aging. This cost-saving approach helps satisfactorily explain experimental observations without any fitting procedures. Our theoretical results would have profound implications for enhancing the applicability of amorphous indomethacin to disease treatment and prevention.