Glycyrrhizae Radix, B.P., Liquorice Root. Glycyrrhizinum Ammoniatum, Ammoniated Glycyrrhizin.

Botanical name: 


Liquorice root (Glycyrrhiza, U.S.P.; Licorice Root) consists of the dried peeled root and peeled underground stem of Glycyrrhiza glabra, Linn. (N.O. Leguminosae), and other species. Glycyrrhiza, U.S.P., may be obtained from either G. glabra or G. glandulifera;the latter contains an amorphous bitter substance named glycyramarin. The plants are widely distributed over Southern Europe, and are cultivated to a limited extent in England, but the official drug is imported chiefly from Spain. In the autumn, the whole of the underground part of the plant is collected, peeled, and carefully dried. Peeled Spanish liquorice root occurs in long cylindrical pieces, varying usually from 1 to 2 centimetres in thickness. Its surface is yellow in colour, and nearly smooth, but somewhat fibrous, owing to the exposure of the bast fibres caused by the peeling. The fracture is fibrous in the bark and splintery in the wood. A smoothed transverse section appears dense, and exhibits a yellow radiate wood, with large vessels, and very numerous medullary rays; it also exhibits a comparatively wide bark, containing numerous radially arranged yellowish groups of strongly thickened bast fibres, accompanied by small prismatic crystals of calcium oxalate; groups of sieve tissue are also numerous, the outer ones being collapsed. The medullary rays of the wood are three or four cells wide, and separate the wood bundles, which are characterised by the presence of large (100μ wide), yellow vessels, the pores of which are elongated or large, areolated, rounded, or angular. There is an abundance of starch grains and of calcium oxalate crystals in the parenchyma; the former are small (3μ to 15μ) and rounded or ovoid in shape, the crystals are prismatic (10μ to 30μ). Liquorice powder is characterised by the yellowish groups of thick-walled bast fibres, accompanied by regular rows of cells with prismatic crystals of calcium oxalate, by the abundance of small starch grains (3μ to 15μ), and by the large, thick-walled, yellow, pitted vessels. The odour of the drug is faint, and its taste characteristic, being sweet and free from any bitterness. Russian and Persian liquorice root obtained from G. glandulifera, W. and K., is very largely used. It is imported chiefly in the peeled condition, and may be distinguished from the official (Spanish) root by its larger size, more fibrous and less dense structure, and distinct acrid after-taste; in addition, it consists almost entirely of root with very little underground stem.

Constituents.—The chief constituent of liquorice root is glycyrrhizin, which can be obtained as a sweet, white, crystalline powder, consisting of the calcium and potassium salts of glycyrrhizic acid; the acid has been obtained in colourless crystals, melting at a temperature near 205°, and imparts a sweet taste to water in a dilution of 1 to 20,000. The quantity present has been variously estimated at from 2 to 7 per cent. On hydrolysis, the acid yields glycyrrhetinic and glycuronic acids. The drug also contains sugar, starch (29 per cent.), proteins, fat, resin, and asparagin 1.25 per cent. When dried at 100° it yields from 3 to 4 per cent. of ash, and from 15 to 27 per cent. of aqueous extract.

Action and Uses.—Liquorice root is demulcent and mildly expectorant. For these properties it is a constituent of domestic remedies for cough and bronchitis, generally with decoction of linseed or marshmallow. Powdered liquorice root is used as a flavouring agent in Pulvis Glycyrrhizae Compositus; for medicinal use the solid and fluid extracts are usually administered. Extractum Glycyrrhizae enters into the composition of cough lozenges and pastilles with sedatives and expectorants. The liquid extract is used in cough mixtures and to disguise the taste of nauseous medicines, especially the alkali iodides, ammonium chloride, quinine and liquid extract of cascara. It should, however, be prescribed only in alkaline or neutral solution. Powdered liquorice root is frequently used as an absorbent pill excipient.


Elixir Adjuvans, B.P.C.—ADJUVANT ELIXIR 1 (liquid extract) in 8.
A useful flavouring agent for mixtures, in the proportion of 1 part to 8, to disguise the taste of cascara, ammonium chloride, and the alkali iodides. Dose.—4 to 8 mils (1 to 2 fluid drachms).
Elixir Adjuvans, C.F. and U.S.P.—ADJUVANT ELIXIR, C.F. AND U.S.P.
Fluidextract of glycyrrhiza, 12; aromatic elixir, sufficient to produce 100.
Elixir Glycyrrhizae, C.F. and N.F.—ELIXIR OF GLYCYRRHIZA. Syn.—Elixir of Licorice.
Fluidextract of glycyrrhiza, 12.5; aromatic elixir, 87.5; magnesium carbonate, 1. Triturate the magnesium carbonate with the fluidextract, add the elixir, and shake the mixture occasionally (luring one hour, then filter. Average dose.—8 mils (2 fluid drachms).
Extractum Glycyrrhizae, B.P.—EXTRACT OF LIQUORICE.
Liquorice root, in No. 20 powder, 100; distilled water, 500. Add the drug to 250 of the water, set aside for twenty-four hours, then strain and press; repeat the process with the same quantity of water, but set aside for six hours only. Finally mix the liquids, heat the mixture to 100°, strain through flannel, and evaporate to a soft extract. Extract of liquorice is used in pills, and when excess of moisture is removed by evaporation, as "liquorice pellets," with or without menthol. These are sucked slowly for catarrhal colds. Extract of liquorice is also made into lozenges and pastilles of various forms, especially with aniseed or ammonium chloride. "Salmiak" tablets are an esteemed Continental remedy, composed of ammonium chloride and liquorice. Extract of liquorice is sometimes ordered as a constituent of fluid medicines. It should be rubbed in a mortar with a little warm water to effect solution. For incompatibles see Extractum Glycyrrhizae Liquidum. The commercial extract sold simply as "liquorice" in flattened rolls or sticks contains a variable proportion (10 to 40 per cent.) of insoluble matter.
Extractum Glycyrrhizae, U.S.P.—EXTRACT OF GLYCYRRHIZA.
This preparation is the ordinary commercial extract of liquorice root, in flattened cylindrical rolls, containing not less than 60 per cent. of matter soluble in cold water.
Extractum Glycyrrhizae Purum, U.S.P.—PURE EXTRACT OF GLYCYRRHIZA.
Liquorice root, in No. 20 powder, 100; solution of ammonia (10 per cent), 1.5; glycerin, a sufficient quantity; water, a sufficient quantity. The liquorice is first macerated with a portion of a mixture of the ammonia and 300 of the water, and then percolated with the remainder, and finally water is passed through the percolator until the root is exhausted. The liquid is evaporated to a pilular consistence, and while this is warm 5 per cent. of its weight of glycerin is added. Average dose.—1 gramme (15 grains).
Extractum Glycyrrhizae Liquidum, B.P.—LIQUID EXTRACT OF LIQUORICE.
Liquorice root, in No. 20 powder, 100; distilled water, 500; alcohol, a sufficient quantity. Proceed as in the case of Extractum Glycyrrhizae, but stop the evaporation when the strained liquid, after cooling, has a specific gravity of 1.20; add to the liquid one-fourth its volume of alcohol, and filter after standing for twelve hours. Liquid extract of liquorice is used for its expectorant and demulcent properties in catarrhal conditions, and as a flavouring agent (for those who do not object to its sweetness) to disguise the taste of ammonium chloride, aloes, the iodides, quinine, etc. It is compatible with alkalies, but incompatible with acids. Not only are acid mixtures of the liquid extract very unsightly, but in such combinations the flavour of the liquorice is to a great extent lost. The deposit often found in the liquid extract is due to the formation of acid as a result of fermentation, by which a portion of the glycyrrhizin is precipitated. Strong solutions of sodium or magnesium sulphate precipitate liquid extract of liquorice, as do acid solutions of quinine. Solutions of the neutral soluble salts of quinine make less unsightly mixtures with the liquid extract, and the bitterness is well covered. Liquorice is a suitable flavouring agent for liquid extract of cascara. Dose.—2 to 4 mils (½ to 1 fluid drachm).
Extractum Glycyrrhizae Spirituosum, I.C.A.—SPIRITUOUS EXTRACT OF LIQUORICE. Syn.—Alcoholic Extract of Liquorice.
Extract of liquorice, 50; alcohol, 25; distilled water, sufficient to produce 100. Mix the extract with sufficient of the distilled water to dissolve it, and add the alcohol; then make up the required volume with distilled water, stirring constantly, and filtering if necessary. Spirituous extract of liquorice is official in India and the Eastern Colonies, where the proportion of alcohol may be increased to one fourth by weight of the finished product, in order to prevent fermentation. Dose.—2 to 4 mils (½ to 1 fluid drachm).
Fluidextractum Glycyrrhiziae, U.S.P.—FLUIDEXTRACT OF GLYCYRRHIZA.
Prepared by exhausting 100 of liquorice root, in No. 20 powder, by percolation with boiling water, evaporating the percolate to 45, cooling, adding 45 of alcohol (95 per cent.), setting aside for three days, then filtering, distilling until the distillate measures 50 and adding to the residue 25 of glycerin, 5 of solution of ammonia (10 per cent.), 20 of alcohol (95 per cent.), and sufficient water to produce 100. Average dose.—2 mils (30 minims).
Mistura Glycyrrhizae Composita, B.P.C.—COMPOUND LIQUORICE MIXTURE. Syn.—Compound Mixture of Glycyrrhiza; Brown Mixture.
Extract of liquorice, 3; syrup, 5; gum acacia, in coarse powder, 3; compound tincture of camphor, 12: antimonial wine, 6; spirit of nitrous ether, 3; distilled water, sufficient to produce 100. This preparation is a popular remedy for coughs in the acute and sub-acute stages of bronchitis and laryngitis. It allays irritation, promotes the activity of the bronchial and laryngeal mucosa, and so increases secretion, and promotes expectoration. Dose.—4 to 8 mils (1 to 2 fluid drachms).
Mistura Glycyrrhizae Composita, U.S.P.—Similar to B.P.C., but prepared with Extractum Glycyrrhizae Purum, U.S.P.
Pulvis Glycyrrhizae Compositus, B.P.—COMPOUND POWDER OF LIQUORICE.
Senna, in fine powder, 2; liquorice root, in fine powder, 2; fennel fruit, in fine powder, 1; sublimed sulphur, sifted, 1; refined sugar, in powder, 6. Mix the powders intimately. This preparation is a mild laxative suitable for the use of children and delicate persons. Dose.—4 to 8 grammes (60 to 120 grains). For a similar preparation without sugar see Pulvis Sennae Aromaticus.
Pulvis Glycyrrhizae Compositus, U.S.P.—COMPOUND POWDER OF GLYCYRRHIZA.
Senna, in No. 80 powder, 18; liquorice root, in No. 80 powder, 23.6; washed sulphur, 8; oil of fennel, by weight, 0.4; sugar, in fine powder, 50. Average dose.—4 grammes 60 grains).
Trochisci Glycyrrhizae B.P.C.—LIQUORICE LOZENGES. Syn.—Brompton Cough Lozenges.
Each lozenge contains extract of liquorice, 3 grains; oil of anise, ½ minim; with simple basis. These lozenges are given to allay cough.
Trochisci Glycyrrhizae et Opii, U.S.P.—TROCHES OF GLYCYRRHIZA AND OPIUM.
Extract of glycyrrhiza; in fine powder, 15 grammes; opium, 5 decigrams; acacia, 12 grammes; sugar, 20 grammes; oil of anise, 2 decimils (0.2 milliliters); water, a sufficient quantity. To make 100 troches.


Ammoniated glycyrrhizin may be prepared in the following manner:—Macerate 100 of liquorice root in No. 20 powder in a mixture of 95 of distilled water and 5 of solution of ammonia for twenty-four hours, then transfer to a percolator and gradually add distilled water until the percolate measures 100; add sulphuric acid slowly and with constant stirring to the percolate until a precipitate ceases to form; collect the precipitate on a strainer, wash until free from acid, redissolve in water with the aid of solution of ammonia, filter if necessary, and repeat the precipitation, with sulphuric acid; again collect, wash, and dissolve the precipitate in a sufficient quantity of solution of ammonia, previously diluted with an equal volume of distilled water; finally, evaporate the clear solution to a thin syrup, scale on porcelain tiles or sheets of glass, and preserve the dry product in well-closed vessels. Ammoniated glycyrrhizin is official in the U.S.P., and occurs in the form of dark brown or brownish-red odourless scales, having a very sweet taste. At 100° the scales become darker in colour, and at a higher temperature melt with decomposition; on complete incineration not more than a trace of ash should be left. The aqueous solution treated with excess of acid throws down a precipitate of glycyrrhizin, which, when dissolved in hot water, forms a jelly on cooling, and this when washed with diluted alcohol and dried occurs as an amorphous yellow powder having a strong bitter-sweet taste and an acid reaction. The scales consist chiefly of ammonium glycyrrhizate, but may contain a variable proportion of glycyramarin, if Russian or Persian liquorice root has been used.

Readily soluble in water or diluted alcohol, insoluble in ether, sparingly soluble in strong alcohol.

Uses.—Ammoniated glycyrrhizin is used as a substitute for extract of liquorice in neutral mixtures. One grain is sufficient to flavour 6 fluid ounces of mixture. Glycyrrhizin is incompatible with acids.

Dose.—¼ to 3 decigrams (½ to 5 grains).

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