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, amenorrhœa, 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.