Chloroquine is one of the most popular synthetic quinolinemethanolamines that has ever been used in the chemotherapy of malaria. Other derivatives, such as quinacrine, are also highly potent antimalarial agents. Over the past twenty years, however, many chloroquine-resistant strains of Plasmodium falciprium and other parasites have arisen, leading to renewed activity in the synthesis of antimalarial agents. Side effects include respiratory depression, cardiovascular collapse, shock, convulsions, and death.