Thermoanalytical Study and Purity Determination of Azelastine Hydrochloride and Emedastine Difumarate

Abstract

The thermal behavior of antihistaminic drugs, azelastine hydrochloride, and emedastine difumarate in their drug substances were investigated using different thermal techniques. The thermogravimetry was used to study the thermal degradation and kinetic parameters; activation energy (Ea), frequency factor (A), and reaction order (n) of both drugs. The data revealed that the cited drugs followed first order kinetic behavior. The fragmentation pathway of azelastine hydrochloride with mass spectrometry was taken as example; to correlate the thermal decomposition with the resulted MS-EI. The melting point and purity were determined using DSC and Van’t Hoff equation for the studied drugs. The results were in agreement with the recommended pharmacopoeias.