Evaluation of activation energy conformity derived from model-free non-isothermal predictions and Arrhenius isothermal results

In this study, the activation energy of HCTZ-lactose interaction was determined and compared to isothermal and non-isothermal methods. DSC data were fitted to different thermal models such as Friedman, Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose, and the activation energy was calculated subsequently. Isothermal studies were performed by heat ovens, and analysis was done using high-performance liquid chromatography technique, and the activation energy (E (a)) were calculated according to Arrhenius method. To date, no practical evaluations has been performed in the literature on the conformity of these different heating methods in incompatibility studies. The kinetic data obtained from the isothermal and non-isothermal methods showed no significant difference. The current study demonstrated a good conformity between the isothermal and non-isothermal kinetic results, and thus, it can be suggested that DSC-based kinetic analysis can provide a simple, reliable and fast comparative data in the kinetic evaluation of an incompatibility seen in early stages of preformulation studies. Finally, the advantages and drawbacks of each method are fully discussed.