Antimalarial drugs and their actions.

New antimalarial drugs are required, partly because of the emergence of drug resistant strains of malaria parasites and partly because better compounds are needed to cure relapsing tertian malaria. In reviewing the diverse modes of action of currently used antimalarials, against a background of the pathogenesis of malaria, attention is drawn to deficiencies in our knowledge. Even less do we understand how the malaria parasite becomes resistant to certain drugs, in particular chloroquine. New approaches to the problem include the application of combinations of existing antimalarials, and the search for new drugs on an unprecedentedly vast scale. Out of over a quarter million compounds that have recently been screened, a handful are now in clinical trial and are showing great promise for the treatment of multiple resistant falciparum malaria. The paper concludes by summarizing current recommendations for the prophylaxis and therapy of malaria due to drug resistant parasites.