Marrubium. Horehound.

Horehound consists of the dried leaves and flowering tops of the white horehound, Marrubium vulgare, Linn. (N.O. Labiatae), an erect herbaceous plant indigenous to Britain and widely distributed over Europe. It is official in the U.S.P. It is collected chiefly in the South of France and dried. The plant has a quadrangular, branching stem, covered with dense, whitish woolly hairs. Leaves opposite, petiolate, about 3 to 5 centimetres long, rounded ovate, or ovate-acuminate, with dentate-crenate margin, wrinkled, densely woolly on the under surface. Flowers in verticillasters in the axils of the upper leaves; calyx hairy, and provided with ten recurved, hooked teeth; corolla bilabiate, with a small, erect, and cleft, whitish upper lip. The drug has an agreeable odour, and somewhat aromatic, bitter taste. White horehound is sharply characterised by the dense, woolly hairs, and ten hooked calyx teeth. Other species have occasionally been substituted for it. M. peregrinum, Linn., has ten straight calyx teeth; M. candidissimum has five nearly straight calyx teeth, and is less bitter and less aromatic. Black horehound, Ballota nigra, L., has dark green leaves, with rough, not woolly, hairs, and has a disagreeable odour.

Constituents.—Horehound contains a crystalline bitter principle, marrubiin, together with a little volatile oil and tannin. Marrubiin crystallises in colourless plates or needles, melting at 160°; it is almost insoluble in water, but soluble in alcohol and in ether.

Action and Uses.—Horehound is an expectorant, and, in large doses, laxative. It is a popular domestic remedy for coughs, colds, and pulmonary affections, in the form of infusion, oxymel, and syrup. It is said to be of especial use when the expectoration is. excessive. Horehound candy is similarly employed.

Dose.—1 to 2 grammes (15 to 30 grains).


Infusum Marrubii, B.P.C.—INFUSION OF HOREHOUND. 1 to 20.
Dose.—30 to 60 mils (1 to 2 fluid ounces).
Oxymel Marrubii, B.P.C.—OXYMEL OF HOREHOUND. 1 in 2 (about).
A domestic remedy for coughs. Dose.—2 to 4 mils (½ to 1 fluid drachm).
Syrupus Marrubii, B.P.C.—SYRUP OF HOREHOUND. 1 in 2 (about),
A domestic remedy for coughs. Dose.—2 to 4 mils (½ to 1 fluid drachm).

The British Pharmaceutical Codex, 1911, was published by direction of the Council of the Pharmaceutical Society of Great Britain.