Cinchonidinae Sulphas. Cinchonidine Sulphate.
Related entry: Red Cinchona Bark
C38H46N4O6S,3H2O = 740.526.
Cinchonidine sulphate, (C19H22N2O)2,H2SO4,3H2O, is the salt of a base found in cinchona bark. It is official in the U.S.P. It occurs in the form of colourless, shining, silky crystals, neutral to litmus, without odour, but with a strong, bitter taste. It may contain either three or six molecules of water of crystallisation. Melting-point (of the anhydrous salt), 205°, with darkening. The sulphate should not lose more than 8 per cent. of its weight on drying at 100°. It should only slightly tinge concentrated sulphuric acid. Not more than a slight fluorescence should be noticeable in a solution (1 in 1000) in dilute sulphuric acid (limit of quinine and quinidine). If 5 decigrams be shaken with 20 mils of water at 15° for some time, 5 decigrams of sodium potassium tartrate added, and the mixture left with frequent shaking for an hour, the filtrate should not show more than a faint opalescence on the addition of a drop of solution of ammonia (limit of cinchonine and quinidine).
Soluble in water (1 in 100) more readily on the addition of dilute acid, alcohol (1 in 60) almost insoluble in ether or chloroform.
Action and Uses.—Cinchonidine is the most poisonous of the alkaloids in cinchona bark; it has much the same action as quinine, but it increases reflexes, and in large doses gives rise to well-marked epileptiform convulsions. Cinchonidine sulphate is usually administered with diluted sulphuric acid, as in the case of quinine sulphate, to facilitate solution. Pills may be prepared with glucose or glycerin of tragacanth. An acid sulphate is obtainable, and is more freely soluble.
Dose.—1 to 6 decigrams (½ to 10 grains).