Study of the molecular mobility of (±)-methocarbamol in the amorphous solid state

Abstract

The experimental techniques of differential scanning calorimetry (DSC) and thermally stimulated depolarization currents (TSDC) were used to study the thermal behavior of the pharmaceutical drug (±)-methocarbamol and its slow molecular mobility (in the 10−3–10−2 Hz range) in the amorphous solid state. The possibility of polymorphism was considered based on the DSC results. The glass forming ability and the glass stability were investigated by DSC, and the general kinetic features of the main relaxation, including the fragility or steepness index, were studied by both experimental techniques. The secondary relaxations detected by TSDC revealed fast and slow (Johari-Goldstein) modes. These secondary relaxations of different nature were assigned based on physical aging studies.