United States Dispensatory 1926
Compiled and Edited by Ivor Hughes.

ARNICA. N. F. (Br.) ARNICA Arnic. [Arnica Flowers]
" Arnica is the dried flower-head of Arnica montana Linne (Fam. Composites). Arnica contains not more than 3 per cent, of foreign organic matter." N. F.

"Arnica Flowers are the dried flower-heads of Arnica montana, Linn." Br.

Arnicas Flora, Br.; Leopard's Bane, Wolf's Bane, Mountain Tobacco: Fleurs d'Arnique, Fr.; Flores ArnictB, P. G; Wohlverleihblilthen, Arnicablttthen, Arnika, Blutblume, Gemsblume, Fallkraut, G.; Fieri di arnica, It.; Flor de arnica, Sp.

Arnica montana is a perennial herbaceous plant, having a woody, brownish, horizontal rhizome, from 2 to 10 cm. long, and 0.5 to 5 mm. thick, ending abruptly, and sending forth numerous slender fibers of the same color. The stem is about 3 dm. high, cylindrical, striated, hairy, and terminating in one, two, or three peduncles, each bearing a flower. The radical leaves are ovate, entire, ciliated, and obtuse; those of the stem, which usually consist of two opposite pairs, are lance-shaped. Both are bright green, and somewhat pubescent on their upper surface. The flower-heads are yellow.

This plant is a native of the mountainous districts of western and central Europe, and is found, according to Nuttall, in the northern regions of this country, west of the Mississippi. It has been introduced into England, and might no doubt be cultivated in the United States. The flowers, leaves and root are employed; but the flowers only are official. In the Swiss and German Pharmacopeias the definition of arnica flowers is restricted to the flowers separated from the receptacles, this being done as the latter contain the larvae of Trypeta arnicivora. On the other hand the Austrian Pharmacopoeia permits the use of the entire flower heads, but the receptacles containing larva must be removed.

Description and Physical Properties.
Unground Arnica.� Consisting chiefly of the tubular and ligulate flowers, usually with the involucre and receptacle present; involucral bracts narrowly lanceolate, about 1 cm. long, dark green and pubescent; receptacle slightly convex, deeply pitted and densely short hairy; ray flowers yellow, the ligulate portion up to 2 cm. long, more or less folded lengthwise, 3-toothed, 7- to 12-veined, pistillate; tubular flowers perfect, reddish yellow, stamens without a tail-like appendage; the achenes spindle shaped, 5 to 7 mm. long, dark brown, finely striate; glandular pubescent and surmounted by a pappus a little longer than the achene and composed of a single circle of nearly white barbellate bristles. Odor characteristic and agreeable, taste bitter and acrid.

Powdered Arnica. � Yellowish brown; pollen grains numerous, 0.025 to 0.035 mm. in diameter, spherical triangular in section and spinose; non-glandular hairs of three kinds, either unicellular, 4- to 6-celled, or consisting of a pair of unicellular hairs with numerous pores on the dividing wall; glandular hairs of three kinds, either with a large unicellular stalk and a unicellular glandular head, or with a 4-celled stalk and a unicellular glandular head, or a stalk of a double row of 5 cells which may be more or less broken and a 2-celled, glandular head; pappus consisting of a multicellular axis with unicellular branches." N. F.

Receptacle nearly flat, bristly, with two rows of dark-green, linear-lanceolate, acute, hairy bracts. Each ray-floret possesses a much shriveled dark yellow ligulate corolla which, after expansion in water, exhibits from eight to twelve veins and three terminal teeth. Disc-florets numerous, yellow. Fruits slender, shriveled, with numerous appressed hairs, and crowned with a single row of stiff, whitish, barbed bristles. Slight aromatic odor; taste bitter and acrid." Br.

Arnica flowers of commerce are not infrequently admixed with and substituted by other composite flowers. Farwell states that the heads of Lapachis columnaris T. et G., a western composite, have been offered in large quantities for arnica, Hartwich has recently found a sample of arnica adulterated with the flowers of the common dandelion. Beilstein reported having found in one lot approximately 90 per cent, of the flowers of Inula. The following flowers also have been used: Anthemis tinctoria L., Calendula officinalis L., Doronicum Pardalianches L., Inula britannica L., Scorzonera humilis L., Heterotneca inuloides. The first three of these are distinguished by the fact that the achenes do not have any pappus. In Inula britannica the receptacle is naked and the ligulate flowers are four-nerved. In Scorzonera the flowers are all ligulate and the pappus is feather-shaped. In Heterotheca inuloides the florets have an inner long pappus and an outer short pappus.

The rhizome was formerly official in both the British and U. S. Pharmacopoeias and was described by the latter as follows:

" Rhizome about 5 Cm. long and 3 or 4 Mm. thick; externally brown, rough from leaf-sears; internally whitish, with a rather thick bark, containing a circle of resin-cells, surrounding the short, yellowish wood-wedges, and large, spongy pith. The roots numerous, thin, fragile, grayish-brown, with a thick bark containing a circle of resin-cells. Odor somewhat aromatic; taste pungently aromatic and bitter." U. S., 1890. It appears to contain the same active constituents as the flowers.

The arnicin of Walz (N. Jahrb. Pharm., xiii), extracted from both the root and the flowers, is an amorphous yellow mass of acrid taste, slightly soluble in water, freely in alcohol or ether, and dissolving also in alkaline solutions. It is precipitable from its alcoholic solution by tannic acid or by water. Walz assigns to arnicin the formula C20H3004; other chemists that of C35H54O7. Arnicin has not been proved to be a glucoside, although it is decomposed by diluted acids. Sigel (1873) obtained from dried arnica root about � per cent, of essential oil, and 1 per cent, from the fresh; the oil of the latter had a sp. gr. of 0.999 at 18� C.

The oil was found to be a mixture of various bodies, the principal being the dimethyl ether of thymohydroquinone, C10H12(OCH3) 2, boiling at about 235� C., and "with this, phloryl isobutyrate to the extent of one-fifth of the oil, and the methyl ether of a phlorol. (Pflanzenstoffe, 2d ed., p. 1530.) Kondakow confirmed the results of Sigel's investigations. (J. P. C., 1910, ii, 79.) (See also Gildemeister and Hoffmann, Die Aether-isclie Oele, p. 900.) The water from which the oil separates contains isobutyric acid, probably also a little angelic and formic acids, but neither capronic nor caprylic acid, which had been pointed out by Walz.

Arnica root contains about 10 per cent, of inulin. (Pharmacographia, 2d edition, p. 391.) Klobb reported the presence in arnica flowers of a colorless, Crystalline body which he at first named arnisterin, but in 1905 he changed its name to arnidiol. (Ph. Ztg., 1905, xl, p. 846.)

Uses. � Arnica is an active irritant, which is capable, when taken in overdose, of producing symptoms of violent toxic gastro-enteritis, with great nervous disturbance, reduction or increase of the pulse rate, and collapse. In a number of cases of severe or even fatal poisoning by it, the symptoms have been burning pains in the stomach, vomiting, choleraic diarrhea, giddiness, intense muscular weakness, dilated pupils, finally complete insensibility and collapse. In some cases the disturbances of the gastro-intestinal canal have been absent, and the symptoms have chiefly been of cerebral origin. An ounce of the tincture has produced serious although not fatal, symptoms.

Arnica has been used in Germany in the treatment of palsies and various other diseases, but we have very little positive knowledge concerning its action upon the system, and there is no sufficient reason for believing that it is valuable in the treatment of internal diseases. It is largely employed externally in the treatment of bruises and sprains, generally in the form of the tincture. The powdered flowers and leaves are sternutatory; and the inhabitants of Savoy and the Vosges are said to substitute them for tobacco. A tincture of the root was official in the British Pharmacopoeia, 1898.

Dose, of the flowers, one to two grains (0.6 -1.2 Gm.).

Off. Prep. � Tinctura Arnicas, N. F. (Br.) (from flowers); Fluidextractum Arnica, N. F.

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