Differential scanning calorimetry of chloroquine sulphate exposed to sun, heat and ultraviolet radiation

Abstract

Chloroquine sulphate, like the phosphate, is an antimalarial formulation widely used in the tropics. The stability of such formulations is therefore of interest in the combat against malaria. A DSC study has been made of the effects of exposure to the sun, heat and UV radiation on the stability of chloroquine sulphate, similarly as performed earlier for chloroquine phosphate. When freshly recrystallized from a water-acetone mixture, chloroquine sulphate exhibits two endothermic peaks, at 169.4° and 204.7°, for the expulsion of crystal water (one molecule) and for the melting process, respectively. The exposure of chloroquine sulphate to the sun, heat and UV radiation leads to splitting of the peak for melting.