Antimalarial medications or simply antimalarials are a type of antiparasitic chemical agent, often naturally derived, that can be used to treat or to prevent malaria, in the latter case, most often aiming at two susceptible target groups, young children and pregnant women. As of 2018, modern treatments, including for severe malaria, continued to depend on therapies deriving historically from quinine and artesunate, both parenteral (injectable) drugs, expanding from there into the many classes of available modern drugs. Incidence and distribution of the disease ("malaria burden") is expected to remain high, globally, for many years to come; moreover, known antimalarial drugs have repeatedly been observed to elicit resistance in the malaria parasite—including for combination therapies featuring artemisinin, a drug of last resort, where resistance has now been observed in Southeast Asia. As such, the needs for new antimalarial agents and new strategies of treatment (e.g., new combination therapies) remain important priorities in tropical medicine. As well, despite very positive outcomes from many modern treatments, serious side effects can affect some individuals taking standard doses (e.g., retinopathy with chloroquine, acute haemolytic anaemia with tafenoquine).
Specifically, antimalarial drugs may be used to treat malaria in three categories of individuals, (i) those with suspected or confirmed infection, (ii) those visiting a malaria-endemic regions who have no immunity, to prevent infection via malaria prophylaxis, and (iii) or in broader groups of individuals, in routine but intermittent preventative treatment in regions where malaria is endemic via intermittent preventive therapy. Practice in treating cases of malaria is most often based on the concept of combination therapy (e.g., using agents such as artemether and lumefantrine against chloroquine-resistant Plasmodium falciparum infection), since this offers advantages including reduced risk of treatment failure, reduced risk of developed resistance, as well as the possibility of reduced side-effects. Prompt parasitological confirmation by microscopy, or alternatively by rapid diagnostic tests, is recommended in all patients suspected of malaria before treatment is started. Treatment solely on the basis of clinical suspicion is considered when a parasitological diagnosis is not possible.
