Marrubium (U. S. P.)—Marrubium.
Preparation: Compound Syrup of Hoarhound
"The leaves and tops of Marrubium vulgare, Linné"—(U. S. P.).
COMMON NAMES: Horehound, Hoarhound.
ILLUSTRATION: Bentley and Trimen, Med. Plants, 210.
Botanical Source.—Hoarhound has a perennial, fibrous root and numerous, annual, bushy stems, which are erect, quadrangular, leafy, clothed with fine, woolly pubescence, branching from the bottom, from 1 to 2 feet in height. The leaves are roundish-ovate, crenate dentate, rough and veiny above, woolly on the under surface, 1 or 2 inches in diameter, and supported in pairs upon long petioles; upper ones nearly sessile. The flowers are small, white, in sessile, axillary, hairy dense whorls. Calyx tubular, 5 to 10-nerved, nearly equal, with 5 or 10 recurved, acute, spiny teeth, alternate ones shorter; orifice of the tube hairy. The corolla is tubular, upper lip erect, flattish, and notched; lower spreading and trifid; middle lobe broadest. Stamens 4, didynamous, included beneath the upper lip of the corolla; anthers with divaricating, somewhat confluent lobes, all nearly of the same form. Style with short, obtuse lobes. Achenia obtuse. Seeds 4, in the base of the calyx (L.—W.—G.). A synoptical key to various genera belonging to the natural order Labiatae, based upon the microscopic appearance of the nutlets, by S. E. Jelliffe, is given in the Druggists' Circular, 1897, p. 34.
History and Description.—Hoarhound is indigenous to Europe, but is naturalized in this country, where it is very common. It grows on dry, sandy fields, waste grounds, roadsides, etc., flowering from June to September. The entire plant has a white, hoary appearance. The whole herb is medicinal, and should be gathered before its inflorescence. It has a peculiar, rather agreeable, vinous, balsamic odor, and a very bitter, aromatic, somewhat acrid and persistent taste. Its virtues are imparted to alcohol or water. The U. S. P. describes the drug thus: "Leaves about 25 Mm. (1 inch) long, opposite, petiolate, roundish-ovate, obtuse, coarsely-crenate, strongly rugose, downy above, white-hairy beneath; branches quadrangular, white, tomentose; flowers in dense, axillary, woolly whorls, with a stiffly 10-toothed calyx, a whitish, bilabiate corolla, and 4 included stamens; aromatic and bitter"—(U. S. P.).
Chemical Composition.—J. A. McMaken, in 1845 (Amer. Jour. Pharm., Vol. XVII, p. 1), isolated from the herb of M. vulgare a peculiar crystalline, bitter principle of neutral reaction, insoluble in water, soluble in ether, and more soluble in hot than in cold alcohol. The principle was again discovered, in 1855, by Mein, who named it marrubiin. It was subsequently investigated by Harms (1855), Kromayer (1861 and 1863), and more recently by Hertel (Amer. Jour. Pharm., 1890, p. 273), J. W. Morrison (ibid., p. 327), and Harry Matusow (ibid., 1897, p. 201). The latter, by extraction with acetone, obtained a yield of 0.8 per cent, referred to air-dried herb, and gives marrubiin the formula C30H43O6. The reactions generally confirm those given by Kromayer, only the melting point he found to be at 154° to 155° C. (309.2° to 311° F.), while Kromayer finds 160° C. (320° F.).The substance is not a glucosid. According to Morrison, several distinct bitter principles appear to exist in the plant. The latter also contains traces of volatile oil.
Action, Medical Uses, and Dosage.—Hoarhound is a stimulant tonic, expectorant, and diuretic. Its stimulant action upon the laryngeal and bronchial mucous membranes is pronounced, and it, undoubtedly, also influences the respiratory function. It is used in the form of syrup, in coughs, colds, chronic catarrh, asthma, and all pulmonary affections. The warm infusion will produce diaphoresis, and sometimes diuresis, and has been used with benefit in jaundice, asthma, hoarseness, amenorrhoea, and hysteria; the cold infusion is an excellent tonic in some forms of dyspepsia, acts as a vermifuge, and will be found efficient in checking mercurial ptyalism. In large doses it purges. It enters into the composition of several syrups and candies. Dose of the powder, 1 drachm; of the infusion, or syrup, from 2 to 4 fluid ounces; specific marrubium, 1 to 30 drops.