Halofantrine is a drug used to treat malaria. Halofantrine's structure contains a substituted phenanthrene, and is related to the antimalarial drugs quinine and lumefantrine. Marketed as Halfan, halofantrine is never used to prevent malaria and its mode of action is unknown, although a crystallographic study showed that it binds to hematin in vitro, suggesting a possible mechanism of action. Halofantrine has also been shown to bind to plasmpesin, a haemoglobin degrading enzyme unique to the malarial parasites.