Thermal stability and kinetic degradation study for dihydroartemisinin

Dihydroartemisinin (DHA), the hydrogenated derivative of the naturally originated sesquiterpene lactone artemisinin, is a well-known antimalarial agent that is currently researched because of its potential as an anticancer medication. Because DHA has been associated with a low oral bioavailability and a short half-life, new formulations meant to overcome these shortcomings are currently under development. As such, the present paper aims to present a comprehensive physico-chemical profile of DHA containing data of great importance for the preformulation stages of the drug design process. As instrumental techniques, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) spectroscopy and thermal analysis (TG-thermogravimetric/DTG-derivative thermogravimetric/HF-heat flow) were performed, followed by a kinetic study realized using three isoconversional methods (Friedman-Fr, Flynn-Wall-Ozawa-FWO and Kissinger-Akahira-Sunose-KAS), as well as the nonparametric kinetic method (NPK). FTIR spectroscopy confirmed the identity and purity of DHA, and thermal analysis revealed a relatively low thermal stability and a multistep thermooxidation that was proved during the performed kinetic study. The latter unveiled a two-process decomposition determined by both chemical degradations and physical transformations.