Quinidine. An alkaloid contained in many of the Cinchona Barks, especially in Fibrous Carthagena Bark, C. Condaminea (var. 5 lancifolia), C. lancifolia (Mutis). It is isomeric with Quinine (C10H24N2O4), with four equivalents of Water when crystallized. (Garrod.) The Sulphate of Quinidine (C40H24N2O4, HO, SO, + 6 HO) is sometimes substituted for Sulphate of Quinine. It is much more soluble in Water and in Spirit than in the Sulphate of Quinine.

Med. Prop. and Action. Believed to be the same as those of Quinine, but the relative power of the two alkaloids requires investigation. Dr. Peacock has administered the Sulphate of Quinidine as an anti-periodic, in doses of three to six grains, with perfect success. In some cases a dose of fifteen grains was given at first Dr. Peacock considers Quinidina as efficacious as Quinia, while it possesses the advantage of not giving rise to the disagreeable nervous effects occasionally observed when Quinia is administered in large doses.

Dose of Sulphate of Quinidine, gr. j. - gr. x. - gr. xx.