Thermal stability and kinetic degradation study for dihydroartemisinin

Abstract

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.