Arnica flowers (Arnica, U.S.P.) are the dried flower-heads of Arnica montana, Linn. (N.O. Compositae), a small plant indigenous to Central Europe. The flower-heads are collected entire and dried, but the receptacles are sometimes removed as they are liable to be attacked by insects. The involucre of arnica flowers consists of two rows of dark green, linear-lanceolate pubescent bracts. The ray florets number about sixteen and possess when fresh, conspicuous, orange-yellow, ligulate corollas traversed by seven to nine veins, and terminating in three teeth; during the drying these corollas shrivel very much. The disc florets are numerous and remarkable for the single row of long white barbed bristles, which crowns the fruit. The latter is five-ribbed and covered with appressed hairs. The odour is aromatic and the taste bitter and acrid. The drug should yield about 6 per cent. of ash. The flower-heads of Inula britannica, Linn., are occasionally offered as arnica flowers, but are easily distinguished from the latter.
Constituents.—The chief constituents of arnica flowers are the bitter, yellow, crystalline body arnicin; a volatile oil (0.5 to 1.0 per cent.); and the colourless, crystalline phytosterol, arnisterol.
Action and Uses.—Arnica has an irritant effect upon the stomach and intestines, and may induce paralysis of the nerve centres. It is rarely given internally, but a tincture is used, diluted with water (1 in 40), as a local application to sprains and bruises. When the skin is delicate arnica may cause extensive dermatitis, and it should not be employed if the skin is broken. Arnica flowers are used in preference to arnica rhizome in the North American Colonies.
- Tinctura Arnicae, U.S.P.—TINCTURE OF ARNICA, U.S.P.
- Arnica flowers, in No. 20 powder, 20; alcohol (49 per cent.), sufficient to produce 100. Average dose.—1 mil (15 minims).
- Tinctura Arnicae Florum, I.C.A.—TINCTURE OF ARNICA FLOWERS.
- Arnica flowers, in No. 20 powder, 10; alcohol (45 per cent.), sufficient to produce 100. Tincture of arnica flowers is official for use in the North American Colonies. Dose.—2 to 4 mils (1/2 to 1 fluid drachm).
ARNICAE RHIZOMA, B.P.
Arnica rhizome is obtained from Arnica montana, Linn. (N.O. Compositae), a small plant indigenous to Central Europe. The rhizome and rootlets should be collected in the autumn, after the stem has died down. The horizontal, cylindrical rhizome is dark brown in colour, varying from 2.5 to 5 centimetres in length, and from 4 to 6 millimetres in thickness. It is usually curved, and bears brittle wiry rootlets on its under surface. The surface is rendered rough by the scars left when these break off, together with the encircling scars of cataphyllary leaves. It is often terminated by the hairy remains of the stem and leaves. The transverse section exhibits a rather thick yellowish cortex, near the inner margin of which is a circle of dark oleoresin ducts. Arnica rhizome is not often adulterated, but foreign rhizomes are occasionally present; the genuine drug may readily be distinguished by the characters given. It yields about 8 per cent. of ash.
Constituents.—Arnica rhizome contains from 0.5 to 1.0 per cent. of volatile oil, with a pungent, aromatic taste, and the bitter, yellow, crystalline principle, arnicin. Tannin and inulin are also present, but the drug is free from starch.
Action and Uses.—The action of arnica rhizome is the same as that of the flowers, and a tincture mixed with water (1 in 40) is a popular application for sprains and bruises when the skin is unbroken.
- Extractum Arnicae Liquidum, B.P.C.—LIQUID EXTRACT OF ARNICA. 1 in 1.
- Liquid extract of arnica is diluted with 20 parts of warm water for use instead of the tincture, being further diluted with 30 to 40 parts of water as in the case of the tincture for application on lint to bruises and swellings.
- Linimentum Arnicae, B.P.C.—LINIMENT OF ARNICA. Syn.—Arnica Opodeldoc.
- Tincture of arnica, 5: camphor, 1; hard soap, 4; alcohol, to 20. Liniment of arnica is applied with friction as a mild counter-irritant.
- Tinctura Arnicae, B.P.—TINCTURE OF ARNICA.
- Arnica rhizome, in No. 40 powder, 5; alcohol (70 per cent.), sufficient to produce 100. Tincture of arnica is rarely given internally. Mixed with 30 to 40 parts of water this tincture is applied to chilblains, bruises, and sprains when the skin is unbroken.
The British Pharmaceutical Codex, 1911, was published by direction of the Council of the Pharmaceutical Society of Great Britain.