Qinghaosu-induced changes in the morphology of Plasmodium inui.

The ultrastructural changes induced by the administration of the antimalarial drug, qinghaosu, were studied in monkeys (Macaca assamensis) infected with Plasmodium inui. Significant changes, notably mitochondrial swelling within the parasites but not within host cells, were first observed 2.5 hr after exposure to qinghaosu. This suggests that the target of qinghaosu may be the parasite's mitochondria, as occurs with primaquine. This is in contrast to the most widely used antimalarial drug, chloroquine.