Quinidine, dextro

Quinidine Quinidine, (5-vinyl-2-quinychdinyl)-(6-methyoxy-4-quinolyl)-methanol (18.1.1) is the dextro-isomer of the alkaloid quinine and is one of the four most important alkaloids, which are isolated from the bark of the cinchona tree [1-3]. Quinidine is a secondary alcohol. 

The first successful therapy of a patient with fibrillation occurred in 1914. Wenckebach (16) reported that a Dutch merchant in Java, who was taking quinine for malaria, stated that he could also control his attacks (paroxysms) of auricular fibrillation with this alkaloid. In 1918 Frey (17) found that the dextro-isomer, quinidine, was superior to quinine, and it has remained the therapeutic agent of choice to the present time. Since that date, a rather massive literature on investigations of quinidine s action on the heart has accumulated. Only a small portion of this literature can be cited here although it is to be regretted that many valuable contributions will be slighted. 

The first work on the stereochemistry and optical properties of the cinchona bases was undertaken by Pasteur (70, 145) in 1852. In the course of these investigations Pasteur achieved one of the greatest initial triumphs of stereochemistry, by showing that racemic acids could be resolved through combination with asymmetric alkaloidal bases. He also made the observation, which was to be of fundamental importance in studies on the structure, stereochemistry, and synthesis of the cinchona alkaloids, that the bases were convertible to isomeric substances, now known as toxines, and first classified the natural alkaloids on the basis of their optical properties. Thus, at this early date, the stereochemical relationship of the dextro rotatory substances, quinidine and cinchonine. 

Besides irritant dermatitis to quinine, which seems to be common in the pharmaceutical industry, contact allergic reactions have also been reported (Hardie et al. 1978). Notwithstanding their structural similarity to quinine and quinidine - the former is the /evo-isomer and the latter the dextro-isomer - they do not cross-react. They are a clear example of stereoisomer specificity. 

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