These drugs are generally less dangerous to use than quinine. However, in Southeast Asia and many other regions, types of malaria have developed that are resistant to synthetic drugs. As a result, physicians in those areas are again using quinine. They have found that quinine can help save the lives of people infected with multidrug-resistant forms of the disease. Quinine is also used to relieve nighttime leg cramps.
Many physicians prescribe the drug quinidine to treat and correct certain disorders of heart rhythm.
Quinidine has the same chemical formula as quinine and differs from quinine only in the way its atoms are arranged. Physicians believe that both drugs, particularly quinine, may cause abnormalities in unborn children. For this reason, pregnant women should not take quinine and quinidine without first consulting a physician. Cinchona trees first grew along the eastern slopes of the Andes Mountains in South America. In the early 1600's, Spanish explorers and missionaries found that the Indians of the region used the bark of the trees as medicine.