Quininae Hydrochloridum Acidum, B.P. Acid Quinine Hydrochloride.
C20H26N2O2Cl2, 3H2O = 451.196.
Acid quinine hydrochloride, or quinine dihydrochloride, C20H24N2O2, 2HCl, 3H2O, may be prepared by adding a solution of 4.45 of barium chloride in 50 of water to a solution of 10 of quinine acid sulphate in 50 of water. The two solutions are mixed, and, after standing for some time, filtered. The filtrate is tested for barium and adjusted, if necessary, with solution of quinine sulphate, evaporated, and set aside to crystallise. It may also be prepared by dissolving 10 parts of quinine hydrochloride in 20 parts of water, and adding 3.7 parts of 25 per cent. hydrochloric acid, filtering and crystallising. Quinine acid hydrochloride occurs in the form of white, glistening crystals, or as a dry, odourless, white, crystalline powder, having a very bitter taste. The aqueous solution of the salt has an acid reaction. According to the B.P. formula, the salt should contain 71.86 per cent. of anhydrous quinine, 16.15 per cent. of hydrochloric acid, and 11.98 per cent. of water of crystallisation, equivalent to three molecules; and at a temperature of 100° it is said to lose not more than 12 per cent. of water, when it becomes opaque and loses its brilliancy; but the salt as found in commerce is practically anhydrous.
Soluble in water (2 in 1.5), alcohol (1 in 5), chloroform (1 in 7) insoluble in ether.
Action and Uses.—This salt is employed principally for hypodermic use; solutions may be prepared containing I grain in 5 minims, and may be used in malaria, ague, rheumatism, typhoid fever, or whenever quinine by the mouth causes gastric irritation (see Quininae Hydrobromidum Acidum; Solutions of 1 gramme in 60 mils are given intravenously in malignant malaria. On account of its ready solubility it is often preferred to the sulphate for general use. It is incompatible with potassium iodide.
Dose.—½ to 6 decigrams (1 to 10 grains).