Origin and Properties

Glycyrrhiza glabra, which is officinally recognized as the source of this root, is an herbaceous perennial, inhabiting the South of Europe, and in general the countries bordering on the Mediterranean, and cultivated in the more northern parts of the continent. it is supposed that another species, G. echinata, which grows wild in the South of Italy, may contribute to the commercial supplies of the drug. it is brought to this country from different ports of the Mediterranean, and is derived chiefly from Sicily, Italy, and the North of Spain.

The dried root is in long, cylindrical pieces, about as thick on the average as the finger, wrinkled longitudinally, fibrous, of a grayish-brown colour on the surface, and yellow within. it yields a soft, loose, yellow or grayish-yellow powder. it has no smell, but a sweet, mucilaginous, somewhat acrid, and agreeable taste. Both water and alcohol extract its virtues. These, so far as the demulcent property is concerned, reside in a peculiar sweet principle, called glycyrrhizin. The principle upon which the acrimony depends has probably not been completely isolated; though an oleo-resinous matter has been obtained, having an acrid taste.

Glycyrrhizin is a yellow, transparent, very sweet substance, scarcely soluble in cold, but very soluble in boiling water, with which it gelatinizes on cooling, soluble in alcohol, and forming insoluble compounds with the acids. it differs from sugar in being insusceptible of the vinous fermentation. As it exists in the root, it is supposed to be rendered soluble by the presence of inorganic bases. For the method of procuring it, see the U. S. Dispensatory. it is not medically employed in a separate state.

Liquorice {Extraclum Glycyrrhizae, U. S., Br.) is obtained by boiling the root with water, and evaporating the decoction. Most of what is consumed in this country is imported from the Mediterranean; but considerable quantities are at present made here from the imported root. As brought from abroad, it is generally in cylindrical rolls often somewhat flattened, or in cubical masses, and is usually purified for medical use by solution in water, and evaporation. It is thus separated from insoluble matters, and in some degree also from the acrid principle; but it is doubtful whether the latter exemption is on the whole a merit, considered in a therapeutic point of view. Thus refined, it is in various shapes, sometimes in small cylindrical sticks about as thick as a pipe-stem, sometimes in flattened, lozenge-like pieces.

Liquorice is black, hard, brittle, with a shining fracture, a slight odour, and a peculiar, very sweet, somewhat acrid taste. With the exception of impurities, it is almost wholly soluble in water.

Medical Effects and Uses

Liquorice root and its extract are commonly regarded as simply demulcent; but, from their usefulness in catarrhal affections, taken in connection with their acrid taste, I am disposed to think that they are something more, and that, like seneka, they have a tendency to act on the pulmonary apparatus, and especially on the bronchial mucous membrane. The root is used in decoction, generally associated with acrid substances, which it is supposed to render milder through its demulcent properties, while it improves the taste. Thus, it is an ingredient in the officinal decoctions of mezereon and guaiacum, and compound decoction of sarsaparilla, and is very frequently associated with seneka. The powder is much employed in the preparation of confections, and is an excellent excipient for liquids made into pills, as well as accompaniment of pills in the pill-box. To the latter purpose it is adapted by its absorbent property, by which it prevents the pills from adhering together, while it gives them a coating not unpleasant to the taste.

The extract, commonly called liquorice, is much used for coughs, as well as to impart flavour and demulcent properties to mixtures and lozenges, especially those given in bronchial affections. It is also often added to decoctions and infusions, with the same objects. Held in the mouth, and allowed slowly to dissolve, it alleviates cough, and, in chronic cases, or somewhat advanced stages of the acute, operates, I believe, favourably, by an alterative influence on the diseased membrane. In cough mixtures, from half an ounce to an ounce may be added to eight fluidounces of the menstruum.