Quininae Salicylas. Quinine Salicylate.
C54H60N4H10, H2O = 942.536.
Quinine salicylate, (C20H24N2O2HC7H5O3)2, H2O, may be prepared by dissolving 3.89 of sodium salicylate in 120 of water, heating to boiling, and adding 10 of quinine sulphate, with constant stirring; the quinine salicylate formed is thrown out as a crystalline precipitate; when cold the precipitate is collected, washed with cold water until free from sulphates, drained on a porous tile, and allowed to dry in the air. It may also be prepared by neutralising an alcoholic solution of quinine with salicylic acid, concentrating the solution, and crystallising. The salt contains 68.79 per cent. of anhydrous quinine, 29.29 per cent. of salicylic acid, and 1.91 per cent. of water of crystallisation. Quinine salicylate is official in the U.S.P. It occurs in the form of white, silky, acicular crystals, or is a slightly crystalline powder, permanent in the air, assuming a pinkish colour on keeping. The aqueous solution is alkaline to red litmus and has a bitter taste, and when treated with diluted sulphuric acid assumes the characteristic blue quinine fluorescence. Heated at 100°, it loses its water of crystallisation (rather less than 2 per cent.). At 183°, it begins to melt, with decomposition; at 187°, is wholly melted, forming a red liquid; and on complete ignition it slowly burns, without leaving any residue. It gives the thalleioquin reaction. Sulphuric acid, containing about one-fifth of its volume of formaldehyde, yields a pink colouration. It should not contain more than traces of chlorides or sulphates, and should prove to be free from excessive amounts of other cinchona alkaloids when treated as follows:—Mix 2 grammes of the salt with 10 mils of water in a separator, add a slight excess of ammonia, extract the alkaloid by shaking with ether several times, evaporate the ethereal solution, dissolve. the residual alkaloid in alcohol, and exactly neutralise it with sulphuric acid; then evaporate the neutral solution to dryness, and conduct the examination as described under Quininae Sulphas.
Very slightly soluble in water; in alcohol (1 in 24), chloroform (1 in 25).
Action and Uses.—This salt of quinine is sometimes employed in acute rheumatism and rheumatic gout for its action on metabolism, as an antiseptic and antipyretic in typhoid fever, and as an analgesic in neuralgia and sciatica. It is best administered in cachets or pills, or suspended in water with Pulvis Tragacanthae Composites. It should not be prescribed with mineral acids, which decompose the salt, sometimes with deposition of crystals of salicylic acid. It may conveniently be given as Granulae Quininae Salicylatis. Saloquinine is quinine salicylic ester; it is insoluble in water, and has been recommended for use in malaria, rheumatism, and sciatica; dose, 1 to 20 decigrams (2 to 30 grains). It has the advantage of being tasteless. Saloquinine salicylate or Rheumatin is used similarly; dose, 1 to 10 decigrams (2 to 15 grains), or more.
Dose.—½ to 3 decigrams (1 to 5 grains).
- Granulae Quininae Salicylatis, B.P.C.—GRANULAR EFFERVESCENT QUININE SALICYLATE. 1 in 50.
- Dose.—4 to 8 grammes (60 to 120 grains).