Quinine lactate, C20H24N2O2C3H6O3, may be prepared by adding 10 of quinine to about 150 of hot water, and neutralising it with sufficient lactic acid (3.2 parts), and boiling the liquid. The neutral solution is filtered while still hot, evaporated at a temperature not exceeding 60°, and allowed to crystallise. It contains 78.26 per cent. of anhydrous quinine, and 21.73 per cent. of lactic acid. Quinine lactate occurs in the form of anhydrous, colourless, prismatic needles, resembling quinine sulphate in appearance, or as a white, crystalline or granular, amorphous powder. Its solutions are neutral. It is stated that a strong aqueous solution for hypodermic use (1 in 4) may be made by neutralising the alkaloid with lactic acid and evaporating to the required bulk.
Soluble in water (about 1 in 6), boiling water (1 in less than 1), very soluble in alcohol, nearly insoluble in other.
Action and Uses.—Quinine lactate is the most soluble neutral salt of quinine. It is employed hypodermically, and I per cent. solutions are used as injections in gonorrhoea.
Dose.—1/2 to 3 decigrams (1 to 5 grams).
The British Pharmaceutical Codex, 1911, was published by direction of the Council of the Pharmaceutical Society of Great Britain.