Gentian root (Gentian, U.S.P.) consists of the dried rhizome and roots of Gentiana lutea, Linn. (N.O. Gentianeae), a perennial herb indigenous to Central Europe. The rhizomes and roots are collected in the autumn and dried. When fresh they are yellowish-white internally, but gradually become darker by slow drying, during which a characteristic odour is developed, a process which is sometimes unduly prolonged. Occasionally they are longitudinally sliced and quickly dried, the drug then being pale in colour and unusually bitter in taste, but this variety is not official. The drug occurs in nearly cylindrical pieces, about 15 to 20 centimetres long, and seldom exceeding 2.5 centimetres in thickness. It is yellowish-brown in colour, and longitudinally wrinkled. When moist it is tough and flexible, but brittle when dry, the fractured surface being of a reddish-yellow colour. A transverse section exhibits a dark cambium ring, separating a somewhat thick bark from the large central wood, which is largely parenchymatous, and exhibits no distinct radiate structure. The rhizome may be distinguished by the absence of well-marked longitudinal wrinkles, and the presence of transverse annulations. Its odour is characteristic, and its taste at first sweet, afterwards bitter. During the slow drying of the root, unduly prolonged hydrolysis of the glucosides, and fermentation of the gentianose present may take place, with progressive diminution in the amount of water-soluble substances present in the root; but slow drying is often employed to prevent deterioration in colour and improve its aroma. Good gentian root yields about 40 per cent. to cold water; highly fermented root may yield as little as 13 per cent. It leaves, on incineration, from 2.5 to 4.5 per cent. of ash. Both the bark and wood of the root consist chiefly of parenchymatous tissue, the cells of which contain numerous minute crystals, and small oil globules, but at most only an occasional starch grain. The vessels are scattered, and either isolated or in small groups; there are no sclerenchymatous cells or fibres in any part of the drug. Gentian powder is well characterised by presenting the above microscopical characters. Commercial powdered gentian root is not infrequently grossly adulterated with ground almond shells, olive stones, various oil cakes, etc., which may readily be detected on microscopical examination. The roots of other species of Gentiana—G. purpurea, Linn., G. pannonica, Scop., G. punctata, Linn., are sometimes collected and dried. They are, as a rule, smaller than the official gentian, but possess similar properties. Gentian root of pale colour and very bitter taste is occasionally seen on the market; whether this is the root of G. lutea, rapidly dried so as to avoid fermentation, or whether it is the root of different species of Gentiana, is at present unknown.
Constituents.—Fresh gentian root contains three bitter principles, gentiopicrin, gentiin, and gentiamarin, of which the last two only are found in the drug, the. gentiopicrin having been hydrolysed by the fermentative changes which take place to a greater or less extent during the process of slow drying. Gentiopicrin forms pale yellow crystals, melting at 191°, and is hydrolysed by emulsin or by dilute mineral acids to gentiogenin and dextrose. Gentiin, which is present in much smaller quantity, is also crystallisable and glucosidal, but gentiamarin is amorphous. In addition to these substances, gentian root also contains a yellow crystalline phenol (gentisin or gentianic acid) and a sugar (gentianose), together with pectin and oil. Gentianose is a hexatriose, yielding by partial hydrolysis gentiobiose and levulose, further hydrolysis splitting up gentiobiose into two molecules of dextrose.
Action and Uses.—Gentian is a typical bitter, and is used to increase the appetite in recovery from acute diseases, atonic dyspepsia, and the like. Bitters increase the flow of gastric juice by improving the appetite. They excite the nerve-endings of taste, and it is this which induces the flow of gastric juice. Patients suffering from gastric trouble have a perverted taste, and in such conditions a powerful gustatory stimulant is administered; and experience teaches that this is best attained by some sharp and unpleasant impression such as may be obtained by taking a bitter substance. Since, however, the action of bitters is purely on the taste nerve-endings it is obviously irrational to swallow them, and all that pharmacology demands is that the mouth be rinsed out with them. The compound infusion is a suitable vehicle for alkaline or acid digestive tonics. Extract of gentian is used as a pill excipient, the mucilaginous and saccharine matters extracted from the root possessing good binding power, which, however, is improved by mixing the extract with an equal weight of liquid glucose.
- Extractum Gentianae, B.P.—EXTRACT OF GENTIAN.
- Add the drug to ten times its weight of water, and infuse for two hours; boil for fifteen minutes, decant, press, strain, and evaporate the liquid to a soft extract. Extract of gentian is sometimes used as a pill excipient, alone or mixed with an equal weight of liquid glucose. It has in some degree the bitter properties of the root, but the process used does not extract all the bitter principles. Dose.—1 to 5 decigrams (2 to 8 grains).
- Extractum Gentianae, U.S.P.—EXTRACT OF GENTIAN, U.S.P.
- Gentian, in No. 20 powder, 100; water, a sufficient quantity. The gentian is exhausted by maceration and percolation and the percolate evaporated to a pilular consistence. Average dose.—25 centigrams (4 grains).
- Fluidextractum Gentianae, U.S.P.—FLUIDEXTRACT OF GENTIAN.
- Gentian, in No. 30 powder, 100; alcohol (49 per cent.), sufficient to produce 100. Average dose.—1 mil (15 minims).
- Infusum Gentianae Compositum, B.P.—COMPOUND INFUSION OF GENTIAN.
- Gentian root, thinly sliced, 1.2,5; dried bitter orange peel, cut small, 1.25; fresh lemon peel, cut small, 2.5; distilled water, boiling, 100. Infuse the drugs in the water for fifteen minutes, in a covered vessel, and strain. This infusion is used as a vehicle, and as an aromatic bitter. Dose.—15 to 30 mils (1/2 to 1 fluid ounce).
- Infusum Gentianae Compositum Concentratum, B.P.C.—CONCENTRATED COMPOUND INFUSION OF GENTIAN.
- A product closely resembling compound infusion of gentian is obtained by diluting 1 part of this preparation with 7 parts of distilled water. Dose.—2 to 4 mils (1/2 to 1 fluid drachm).
- Mistura Gentianae, B.P., 1867.—GENTIAN MIXTURE.
- Gentian root, sliced, 2.5; bitter orange peel, cut small, 0.75; coriander fruit, bruised, 0.75; alcohol (60 per cent.), 20; distilled water, sufficient to produce 100. Macerate the gentian root, orange peel, and coriander in the alcohol for two hours; then add the water, again macerate for two hours, and strain through calico. Gentian mixture is employed as a bitter in dyspepsia and in any condition in which it is desired to improve the appetite. Dose.—15 to 30 mils (1/2 to 1 fluid ounce).
- Mistura Gentianae Acida, B.P.C.—ACID GENTIAN MIXTURE.
- Each fluid ounce contains 10 minims of diluted nitro-hydrochloric acid, and 10 minims of emulsion of chloroform, with a sufficient quantity of compound infusion of gentian. This preparation has the action of a simple bitter. It is commonly employed during convalescence. Dose.—15 to 30 mils (1/2 to 1 fluid ounce).
- Mistura Gentianae et Sodae, B.P.C.—GENTIAN AND SODA MIXTURE. Syn.—Mistura Gentianae cum Soda.
- Each fluid ounce contains 15 grains of sodium bicarbonate, with a sufficient quantity of compound infusion of gentian. This mixture is given before meals to promote appetite and to prevent excessive secretion of gastric juice. Dose.—15 to 30 mils (1/2 to 1 fluid ounce).
- Mistura Gentianae et Sodae Composita, B.P.C.—COMPOUND GENTIAN AND SODA MIXTURE.
- Each fluid ounce contains 15 grains of sodium bicarbonate, 5 minims of emulsion of chloroform, 30 minims of tincture of orange, with a sufficient quantity of compound infusion of gentian. This preparation is more agreeable than Mistura Gentianae et Sodae. Dose.—15 to 30 mils (1/2 to 1 fluid ounce).
- Tinctura Gentianae B.P.C.—TINCTURE OF GENTIAN. 1 in 10.
- Used as a bitter. Dose.—2 to 4 mils (1/2 to 1 fluid drachm).
- Tinctura Gentianae Composita, B.P.—COMPOUND TINCTURE OF GENTIAN.
- Gentian root, cut small, and well bruised, 10; dried bitter orange peel, well bruised, 3.75; cardamom seeds, bruised, 1.25; alcohol (45 per cent.), 100. Prepared by the maceration process. Compound tincture of gentian is used as an aromatic bitter and flavouring agent. Dose.—2 to 4 mils (1/2 to 1 fluid drachm).
- Tinctura Gentianae Composita, U.S.P.—COMPOUND TINCTURE OF GENTIAN, U. S. P.
- Gentian, 10; bitter orange peel, 4 cardamom, 1; all recently reduced to No. 40 powder; alcohol (57 per cent.), sufficient to produce 100. Prepared by a process of percolation. Average dose.—4 mils (1 fluid drachm).
The British Pharmaceutical Codex, 1911, was published by direction of the Council of the Pharmaceutical Society of Great Britain.