Artesunate | Sulphadoxine and Pyrimethamine which treat malaria. Artesunate and Pyrimethamine are antiparasitic medicines which work by increasing the levels of haeme in the blood| a substance toxic to the malarial parasite. This kills the parasite and stops the infection from spreading. Sulphadoxine is an antibiotic which stops the bacteria from producing folic acid| a nutrient required for bacterial multiplication.