A drug directed against malaria. The original antimalarial agent was quinine which took its name from the Peruvian Indian word "kina" meaning "bark of the tree." A large and complex molecule , quinine is the most important alkaloid found in cinchona bark. Until World War I, it was the only effective treatment for malaria . In fact, quinine was the first chemical compound to be successfully used to treat an infectious disease. See the entire definition of Antimalarial