Thermal behavior and decomposition kinetics of cinnarizine under isothermal and non-isothermal conditions

Cinnarizine (CIN) is an anti-histaminic drug which is mainly used for the control of vomiting due to motion sickness. The thermal behavior of CIN was investigated using thermogravimetry/derivative thermogravimetry and differential thermal analysis. The kinetic parameters were evaluated by isothermal and non-isothermal conditions including Ozawa's conventional method, Ozawa-Flynn-Wall and Friedman isoconversional methods. The kinetic parameters were determined using the thermogravimetric curves of the decomposition process. The activation energy values obtained were 88.38 and 90.12 kJ mol(-1) for the isothermal and non-isothermal conditions, respectively, with the conventional method. The activation energy values obtained by isoconversional method were practically equal; hence, the reaction involves a single step. Finally, the values of entropy (a dagger S), enthalpy (a dagger H), and Gibbs free energy change (a dagger G) of decomposition reaction were calculated and compared.