Antimalarials prevent and treat malaria, a parasitic disease transmitted by Anopheles mosquitoes. Chloroquine (4-aminoquinoline — accumulates in the parasite food vacuole, inhibits heme polymerization) was for decades the drug of choice, but extensive P. falciparum resistance now limits its use to P. vivax and P. ovale. Hydroxychloroquine is used mainly in autoimmune diseases (lupus erythematosus, rheumatoid arthritis). Artemisinin-based combinations (ACT — artemether-lumefantrine, artesunate-ammodiaquine, dihydroartemisinin-piperaquine) are the WHO gold standard for uncomplicated P. falciparum malaria, with rapid action against young erythrocytic forms. Sulfadoxine-pyrimethamine is used for chemoprophylaxis in pregnant women (IPTp) in endemic areas. Mefloquine and tafenoquine (8-aminoquinoline) have roles in prophylaxis. Primaquine is essential for radical cure of P. vivax hypnozoites (require G6PD deficiency screening). (Sources: DailyMed/FDA, WHO Guidelines 2024, Health Canada)
