kwīˈnīnˌ, kwĭnēnˈ, white crystalline alkaloid with a bitter taste. Before the development of more effective synthetic drugs such as quinacrine, chloroquine, and primaquine, quinine was the specific agent in the treatment of malaria. Almost insoluble in water, it dissolves readily in alcohol and other organic solvents. It is derived from the bark, called quina quina by the indigenous people of Peru, of several species of Cinchona and is used in the form of a salt, especially the sulfate. By the middle of the 17th cent. Jesuit missionaries had brought cinchona bark to Europe from South America, and quinine was isolated in 1820 by the French chemists J. B. Caventou and P. J. Pelletier ; chemical synthesis was achieved in 1944 by R. B. Woodward and W. E. Doering, American chemists.

Certain strains of the malarial parasite Plasmodium falciparum have now developed a resistance to chloroquine, and quinine is again the preferred drug in some regions. Quinine also has been used medicinally to allay fever and pain, to induce uterine contractions during labor, and as a sclerosing, or hardening, agent in the treatment of varicose veins. It is added to soft drinks called tonics, which are often mixed with alcoholic beverages. Excessive dosage or continuous use of quinine may cause cinchonism, characterized by ringing in the ears, headache, dizziness, changes in blood pressure, and even death.

See F. Rocco, The Miraculous Fever-Tree (2003).

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