Antimalarial drugs are designed to combat malaria. The earliest known remedy was derived from the bark of a tree, named after the Peruvian Indian word "kina." This bark contains quinine, a complex and significant molecule, which was the sole effective malaria treatment until World War I. Notably, quinine was the first chemical successfully used to treat an infectious disease. In 1820, J.B. Caventou and P.J. Pelletier crystallized quinine, and in a landmark achievement in synthetic organic chemistry, R.B. Woodward and W. Doering synthesized it for the first time in 1944.Quinine works by disrupting the growth and reproduction of the malaria parasites residing in the host's blood. It helps alleviate the disease's symptoms by removing the parasites from the bloodstream. However, treatment with quinine is not a permanent solution, as many patients experience relapses. This occurs because quinine fails to eliminate parasites outside the red blood cells, allowing them to persist and eventually reinvade, causing a recurrence of the disease.To find a more permanent solution, new drugs were developed during and after World War II to replace quinine. Some, like chloroquine and chloroguanide, are more effective at suppressing the blood-stage growth of the malaria parasite. Others, such as primaquine and pyrimethamine, target both blood and tissue phases, ensuring a complete cure and preventing relapse. While quinine was once used to treat leg cramps, it is no longer FDA-approved for this purpose due to serious side effects like low platelet counts and even death.
