Molecular mobility and stability studies of amorphous imatinib mesylate

Abstract

The proposed study examined the characterization and stability of solid-state amorphous imatinib mesylate (IM) after 15 months under controlled relative humidity (60 ± 5%) and temperature (25 ± 2°C) conditions. After 2 weeks, and 1, 3, 6, and 15 months, the samples were characterized using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray powder diffractometry (XRPD), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM). Additionally, the amorphous form of imatinib mesylate was obtained via supercooling of the melt in a DSC apparatus, and aged at various temperatures (3, 15, 25 and 30°C) and time periods (1–16 h). Glass transition and enthalpy relaxation were used to calculate molecular-relaxation-time parameters. The Kohlrausch–Williams–Watts (KWW) equation was applied to fit the experimental enthalpy-relaxation data. The mean molecular-relaxation-time constant (τ) increased with decreasing ageing temperature. The results showed a high stability of amorphous imatinib mesylate adequate to enable its use in solid dosage form.