DSC kinetic study of the incompatibility of doxepin with dextrose

In the present paper, the physicochemical incompatibility of doxepin with dextrose was evaluated in solid-state mixtures. The compatibility was evaluated using different physicochemical methods such as differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy and mass spectrometry. Non-isothermally stressed physical mixtures were used to study the solid-state kinetic parameters. Different thermal models such as Friedman, Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose were used for the characterization of the drug-excipient mixtures. Overall, the incompatibility of doxepin as a tertiary amine with dextrose as a reducing carbohydrate was successfully assessed. DSC-based kinetic analysis is a simple and fast method in evaluation of different drug-excipient mixtures incompatibility. Finally, it can be recommended to exclude dextrose from doxepin pharmaceutical formulations and also to apply the easy and versatile DSC method in kinetic study of drug-excipient incompatibility.