The neutral sulphate of an alkaloid prepared from hyoscyamus.

It is found also in the seeds of Belladonna Stramonium, and in Duboisia myoporoides, the alkaloid of which (duboisine) is identical with hyoscyamine. Hyoscyamine is isomeric with atropine.

Characters. - Small golden-yellow, or yellowish-white scales or crystals, or a yellowish-white, amorphous powder, deliquescent on exposure to air, odourless, having a bitter and acrid taste and a neutral reaction.

Solubility. - Very soluble in water and in alcohol.

Reactions. - When heated on platinum foil, the salt chars and is finally completely dissipated. An aqueous solution of the salt is not precipitated by test-solution of platinic chloride. With chloride of gold it yields a precipitate, which, when recrystallised from boiling water acidulated with hydrochloric acid, is deposited on cooling (without rendering the liquid turbid) in brilliant, lustrous, golden-yellow scales (difference from atropine). The aqueous solution yields, with test-solution of chloride of barium, a white precipitate insoluble in hydrochloric acid.

Dose. - 1/60 gr. to 1 gr.

Action and Uses. - The physiological action of hyoscyamine is like that of atropine and daturine. Hyoscyamus is used chiefly as an adjunct to purgatives to lessen griping. It is also used to lessen spasm, and to allay pain and irritation of the bladder. It has also been employed as a sedative to the nervous system.