Quininae Tannas. Quinine Tannate.
Quinine tannate may be prepared as follows:—Quinine sulphate, 40, is dissolved in distilled water, 1200, with diluted sulphuric acid, 67; the solution is filtered and mixed with a solution of tannic acid, 80, in water, 560, then with a solution of tannic acid, 20, in water, 320, and solution of ammonia, 20. After twelve hours the precipitate is collected, and washed with water, 400, and gently pressed. It is then boiled in 200 of water, the resulting resinous liquid mass dried first at 30° to 40°, then at 100°, when it is powdered, and stored in a place protected from light. Quinine tannate occurs in the form of a neutral, odourless, greyish or yellowish-white powder, having a faintly astringent, bitter taste. The aqueous solution is blackened by ferric chloride. Shaken with water acidified with nitric acid it should not at once become turbid with silver nitrate nor with barium nitrate solution. Each gramme should yield at least 3 decigrams of the alkaloid dried at 100°. Two decigrams incinerated should leave no residue.
Soluble in water (1 in 800), boiling water (about 1 in 30), alcohol (about 1 in 3)
Action and Uses.—Quinine tannate is specially useful for children on account of its comparative freedom from bitterness. Recent researches appear to show that it is not less active than the other more soluble salts of the alkaloid, and, being only slowly absorbed, it is much more easily tolerated. It has been used especially in whooping cough and malaria. It is best administered in milk, or in tablets prepared with a chocolate basis.
Dose.—½ to 6 decigrams (1 to 10 grains).