Non isothermal decomposition kinetics and compatibility studies of doxepin with sucrose

Abstract

Background: In the present research the incompatibility of doxepin in solid physical mixtures with sucrose as a common pharmaceutical excipient was studied. Methods: Differential scanning calorimetry (DSC) and Fouriertransform infrared (FTIR) spectroscopy were used for the characterization of the doxepin-sucrose incompatibility. Solidstate kinetic parameters were also obtained using different thermal models such as Friedman, Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS). Results: As a result, the incompatibility of doxepin as a tertiary amine with sucrose as a carbohydrate was successfully proved and the activation energy was calculated. Conclusion: It can be recommended to apply DSC based kinetic analysis as a fast and easy method to reveal the kinetic characteristics of the observed pharmaceutical incompatibilities in the formulation step and also to exclude sucrose from doxepin solid and liquid pharmaceutical preparations in order to eliminate possible drug loss and also safety problems originated from the drug and excipient reaction in acute and chronic anxiety drug regimen protocols.