Fig. 29. Arnica montana. Photo: Arnica montana 5. Preparations: Extract of Arnica Root - Fluid Extract of Arnica Root - Tincture of Arnica Flowers - Tincture of Arnica Root - Arnica Plaster

The flower heads, rhizome, and roots of the Arnica montana, Linné.
Nat. Ord.—Compositae.
COMMON NAMES: Arnica, Leopard's bane.
ILLUSTRATION: Bentley and Trimen, Med. Plants, 158.

Botanical Source.—Arnica montana is a rather hairy plant, with a dark or blackish root, from which are given off numerous radicles. The stem is simple, pubescent, rough, obscurely angled, striated; one to three-headed and from 10 to 12 inches in height. The leaves are entire and opposite; the radical ones obovate or oblong, ciliated, five-nerved; the cauline in one or two pairs. The flowers are large, orange-yellow; in erect or drooping heads. The involucre is cylindrical and rough with glands. There are many tubular, five-lobed disk-florets, and about fourteen strap-shaped, three-toothed, striated ray-florets, downy at the base. The achenia are somewhat cylindrical, downy, ribbed, and blackish, with a straw-colored, hairy pappus.

History and Description.—This perennial herb inhabits Siberia; also the cooler parts of Europe from the sea coast to the limits of constant snow; in moist, shady situations, flowering in June and July; it is likewise found in the northwestern parts of the United States. The whole plant has been used in medicine; more especially the flowers. The flowers are compound, radiated, yellow, with a calyx of linear equal follicles, the length of the disc, ligulate, floscules twice the length of the disc, two lines broad, three-toothed, with a sessile pappus, fragile and somewhat scabrous; taste acrid and bitterish; the dust is unpleasant, and causes sneezing. The odor is unpleasant, but is much diminished, as well as the taste, by drying. They yield their properties to water or alcohol. The dried root is about the thickness of a small quill, flexuous, bark brown externally, rugose longitudinally, with a somewhat hard, whitish wood, larger pith, and long, dense radicles on one side; its taste is aromatic, acrid, and slightly bitter. It should be gathered in the spring. Arnica flowers are liable to adulteration with various composite flowerheads, as anthemis, inula, and calendula. As these differ considerably botanically, there will be no difficulty in detecting the spurious flower-heads.

The Pharmacopoeia of the United States gives the following descriptions of the flowers and rhizome:

ARNICAE FLORES (U. S. P.), Arnica flowers.—"Heads about 3 Cm. (1 ¼ inches) broad, depressed-roundish, consisting of a scaly involucre in two rows, and a small, nearly flat, hairy receptacle, bearing about 16 yellow, strap-shaped, ten-nerved ray-florets, and numerous yellow, five-toothed, tubular disk-florets, having slender, spindle-shaped achenes, crowned by a hairy pappus. Odor feeble, aromatic; taste bitter and acrid"—(U. S. P.).

ARNICAE RADIX (U. S. P.), Arnica root.—"Rhizome about 5 Cm. (1 ¾ inches) long and 3 or 4 Mm. (⅛ to ⅙ inch) 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. P.).

Chemical Composition.—Pfaff found the root to contain volatile oil, acrid resin, extractive, gum and woody fiber. Chevallier and Lassaigne found the flowers to contain resin, a bitter, nauseous substance resembling cytisin, gallic acid, a yellow coloring matter, albumen, gum, chloride and phosphate of potassium, traces of sulphates, carbonate of calcium, and silica (T.).

In 1851 Mr. Bastick announced the existence of an alkaloid in the flowers, which he obtained in small quantity and called arnicina (arnicine). It is not volatile, bitter, slightly soluble in water, but more so in alcohol and ether. Its hydrochlorate is crystallizable (P.). Two bodies, known as arnicin, and derived from both the flowers and rhizome, have subsequently been isolated by two observers—Pavesi in 1859, and Walz, in 1861. The principles are totally unlike, though bearing the same name. Pavesi's arnicin is a disagreeably bitter, viscid resin, of a deep-yellow color, dissolving easily in alkaline solutions, from which acids precipitate it, and it dissolves sparingly and with difficulty in both ether and alcohol. Walz's arnicin (sometimes written arnicine, though different from Bastick's alkaloid), on the contrary, is an acrid, amorphous, golden-yellow mass, dissolving sparingly in water, and readily soluble in ether and alcohol. Alkalies also dissolve it. Recently arnicine was isolated from the flowers by Börner (Am. Jour. of Pharm., 1893), who found for it the formula, C12H22O2. It exists in the flowers to the extent of 4 per cent, and is obtainable from a concentrated acetone solution as a micro-crystalline mass, deliquescing after prolonged exposure melts at 40° C, (104° F.), and boils at 83° C. (181.4° F.); is golden-yellow, and easily soluble in ether, alcohol, acetone, benzole, insoluble in water and alkalies. He also found fat (glycerides of palmitic and lauric acids), and a hydrocarbon of the marsh-gas series. A small amount of angelic and formic acids have been obtained from arnica. Dragendorff obtained 10 per cent of inulin from the root (Pharmacographia).

The volatile oil, which is obtained most plentifully from the green rhizome, abounds to the extent of from 0.5 to 1 per cent, and has a specific gravity of 0.990 to 1.000 at 15° C. (59° F.), and contains iso-butyric acid, phlorol-ester, and thymo-hydro-quinone-dimethyl-ether (Schimmel & Co.'s Semi-Annual Report, October, 1893).

Action, Medical Uses, and Dosage.—Locally arnica is irritant, the preparations of the flowers being most powerful. Strong preparations should not be applied full strength, for in some instances of tender skin, or in accidents occurring after its use, an erysipelatous inflammation has followed. Even when used as a local dressing for wounds dangerous inflammation, with vesication, has occurred.

Internally, in large doses, arnica causes heat in the throat, nausea, vomiting, purging, spasmodic contractions of the limbs, difficulty of respiration, and sometimes inflammation of the alimentary canal, and coma. There is no known antidote to its poisonous influences; vegetable acids have been recommended. Two fluid ounces of the tincture has produced death.

In small doses arnica accelerates the pulse, increases the perspiration, excites a flow of urine, and is said to occasionally cause headache and giddiness. It is esteemed as a stimulant in typhoid fever and other adynamic febrile diseases, in chronic palsy, and amenorrhoea; also as a tonic in chronic rheumatism, and as a tonic and diuretic in the asthenic forms of dropsy. In intermittent fever it has proved very successful; also in nyctalopia, and amaurosis (the best remedy); and is reputed to be highly efficacious in constitutional derangements caused by powerful shocks to the brain, from thumps, kicks, etc., in internal pains, and congestions from bruises, deficient action of parts, etc. It has also been recommended in cases of deficient nervous sensibility, languid vascular action, and almost every disease where there is debility, torpor, or inactivity of function. The conditions calling for arnica are those with evidences of spinal innervation. As a specific stimulant to the spinal nerves it is exceedingly prompt in advanced stages of disease, with feeble respiratory power and sleeplessness due to the same cause; also in lack of control over the voluntary discharges. It is indicated in low typhoid states, and in low forms of typhus fever, diarrhoea, and dysentery, always where there is marked depression and debility. In typhoid pneumonia, with marked asthenia and feeble circulation, great depression, low-muttering delirium, and tongue dry and loaded with foul mucus, it is one of the most efficient agents in use. Its action upon enfeebled respiratory efforts is much like that of phosphorus, as is also its effects in sexual debility from abuse, and in paralytic states of the orifices without active inflammation, particularly in the aged. Small doses are very efficient in anemia with weak circulation, general debility, and especially when associated with diarrhoea and dropsy, provided no inflammation is present (Locke). It is a remedy for hectic fever, with diarrhoea or excessive sweating. In rheumatism, with cold skin and debility, it arouses nervous action and stimulates excretion. It is a good agent in myalgia, and one of the best in muscular soreness and pain dependent upon strains, over-exertion, or other injuries. Here it should be applied locally in weak solutions and taken internally. The nervous headache of the debilitated and depressed calls for it, as does debility of the cardiac muscle due to excitement, over-activity, or "heart-strain." The dull aching in the praecordiae, due to such over-action, is relieved by it. Prof. Scudder (Spec. Med.) writes: "I have frequently prescribed it for lame back, backache, and feelings of debility and soreness in the small of the back. It is only useful in those cases where there is feebleness, with deficient circulation; but in these the influence is direct and permanent."

Externally arnica is used in the form of an infusion, a fomentation, or diluted tincture of the flowers, both to prevent and discuss local inflammations, to remove ecchymosis, and as a dressing for cuts, lacerations, contusions, etc. For this purpose the infusion is attended with the least danger. The late Prof. J. M. Maisch prepared a fluid extract of arnica, which has been found very useful as an application for the bites of mosquitoes and other insects, thus: Exhaust powdered arnica flowers, 1 pound, with diluted alcohol; filter; evaporate to the consistence of an extract, and redissolve this in 2 pints of ordinary alcohol. By adding 4 ounces of this fluid extract to 1 pint of glycerin, placing the mixture on a water-bath, so as to expel the alcohol, an elegant glycerole of arnica may be made; it may be made stronger if desired. This may be used in all cases where the local action of arnica is desired.

Dose of the powder, 5 to 10 grains, 2 to 4 times a day; of the infusion, made by adding ½ ounce of the flowers to 1 pint of water, from ½ fluid ounce to 1 fluid ounce; of the extract, which is an excellent form of administration, from 1 to 10 grains, 4 or 5 times a day. Of specific arnica, from 1 to 10 minims. In preparing an infusion of the flowers they should be loosely tied in a bag in order to prevent the down or fine fibers from getting into the infusion, or else they will cause troublesome irritation of the throat, nausea, and vomiting.

Specific Indications and Uses.—Muscular soreness and pain from strains or over-exertion; advanced stage of disease, with marked enfeeblement, weak circulation, and impaired spinal innervation; embarrassed respiration; lack of control over urine and feces; sleeplessness from impeded respiration, and dull praecordial pain from "heart-strain;" muscular pain and soreness when the limbs are moved; tensive backache, as if bruised or strained; cystitis, with bruised feeling in bladder, or from a fall or blow; headache, with tensive, bruised feeling and pain on movement; hematuria, with dull, aching lumbar pain, or from over-exertion. All cases of debility with enfeebled circulation.

Related Species.Arnica foliosa, Nuttall. Northern and western United States, as far south as Colorado, growing in the mountain districts. This and the following species have flowers which resemble very much those of Arnica montana.

Arnica alpina, Olin, United States. Distribution same as A. foliosa.

Arnica nudicaulis, Elliott (Arnica Claytonia, Pursh). United States, from Virginia to Florida, growing in damp, pine barrens and wet sands. Flowers in April and May.

Arnica mollis, W. J. Hooker (Arnica lanceolata, Nuttall; Arnica Chamissonis, Lessing.) Mountainous regions of northern states, especially in New York and New Hampshire. Blooms in July. This and the preceding species are thought to have properties resembling those of Arnica montana.

King's American Dispensatory, 1898, was written by Harvey Wickes Felter, M.D., and John Uri Lloyd, Phr. M., Ph. D.