Sparteinae Sulphas. Sparteine Sulphate.
C15H28N2O4S, 5H2O = 422.394.
Sparteine sulphate, C15H26N3, H2SO4, 5H2O, is a salt of the dibasic alkaloid sparteine, and may be prepared by neutralising the colourless alkaloid (10 parts) with diluted sulphuric acid (about 40 parts of 10 per cent. solution), rapidly concentrating the solution, and allowing to crystallise in a warm place. Under varying conditions it crystallises with different proportions of water, and may also he obtained in the form of an anhydrous salt, but by recrystallisation from diluted alcohol the salt containing five molecules (21.32 per cent.) of water of crystallisation is obtained. It is official in the U.S.P. Sparteine sulphate occurs in the form of colourless, odourless, hygroscopic, rhombohedral crystals, or as a white, crystalline powder, having a slight, saline and bitter taste. The aqueous solution has a weak acid reaction to litmus. Sparteine sulphate when heated to 100° loses its water of crystallisation, the anhydrous salt melting at 150° to 152°. On ignition, it leaves no residue (absence of mineral impurities). If a small quantity of the salt be warmed gently with about one-third of its weight of chromic acid, a distinct odour of coniine is evolved, and a green colouration produced. The 10 per cent. aqueous solution gives with sodium hydroxide a white precipitate, which soon unites into oily drops, and is soluble in ether or chloroform. On warming an alkaline solution, no odour of ammonia should be given off. If 1 decigram be heated with 2.5 decimils (0.25 milliliters) of chloroform, and 1 mil of alcoholic solution of potassium hydroxide, no odour of phenyl isocyanide should be evolved (absence of aniline). The salt should dissolve in concentrated sulphuric acid without colouration (absence of readily carbonisable organic impurities), and if a crystal of potassium bichromate be stirred with the solution a green, but not a violet, colouration should be produced (absence of strychnine). On adding 25 mils of ether to about 1 decigram of the salt, and then a few drops, but not an excess, of solution of ammonia, and afterwards an ethereal solution of iodine (1 in 50), until the solution on shaking turns from orange to dark reddish-brown in colour, the sides of the vessel containing the solution will shortly become covered with minute, dark, greenish-brown crystals.
Soluble in water (2 in 1), alcohol (1 in 5); insoluble in ether or chloroform.
Action and Uses.—The general effects of sparteine resemble those of coniine, but it is very ranch less poisonous. It has very little action on the central nervous system, hut large doses paralyse sympathetic nerve cells and the peripheral terminations of the motor nerves. Depression of autonomic nerve-cells causes a fall in blood pressure with vaso-dilatation, and its employment has been recommended in cases of high blood-pressure. It has no pronounced action on the heart. The diuretic action of preparations of broom-tops is due to scoparin, not to sparteine. Sparteine sulphate is the most commonly used salt of the base, and has been given in doses as large as 8 decigrams (12 grains). It is administered in pills, or used in the form of hypodermic injection, from 1 to 4 decimils (0.1 to 0.4 milliliters) (2 to 6 minims) of a 15 per cent. solution being injected as required.
Dose.—6 to 12 centigrams (1 to 2 grains), or more.