476. Marrubium.—Horehound U.S.P. VIII.
The dried leaves and flowering tops of Marru'bium vulga're Linné.
DESCRIPTION.—Stem white, tomentose; leaves roundish-ovate, about 1 inch (25 mm.) long, obtuse, crenate, downy; flowers whitish, aromatic, and bitter; odor distinct and agreeable; taste aromatic and bitter.
CONSTITUENTS.—Volatile oil in minute quantity, marrubiin, crystalline prisms soluble in hot water and ethereal solvents, insoluble in benzene.
Preparation of Marrubiin.—Treat the infusion with charcoal; exhaust latter with Alcohol, which dissolves marrubiin and tannin; precipitate tannin with lead oxide; exhaust precipitate with alcohol. This leaves behind insoluble tannate of lead and dissolves the bitter principle.
ACTION AND USES.—A bitter tonic, laxative when given in large doses; employed in catarrh and chronic affections of the lungs attended by copious expectoration. Dose: 15 to 30 gr. (1 to 2 Gm.), in infusion or decoction.