Origin. - The dried flower-heads of Arnica montana L., a plant indigenous in the mountainous regions of Europe and Northern Asia, and also found in the northwestern part of America.

Description and Properties. - Heads about 1 to 2 inches (25-50 Mm.) in diameter, depressed-roundish, consisting of a scaly involucre in two rows, and a small, nearly flat, hairy receptacle, bearing about sixteen yellow, strap-shaped, ten-nerved ray-florets and numerous yellow, five-toothed, tubular disk-florets, with slender, spindleshaped akenes crowned by a hairy pappus. Odor feeble and aromatic; taste bitter and acrid.

Arnica flowers contain a glycosid (?), arnicin, a volatile oil, caproic and caprylic acids, resins, tannin, etc.

Dose. - 5-30 grains (0.3-2.0 Gm.) [15 grains (1 Gm.), U. S. P.].

Official Preparation

Tinctura Arnicae - Tincturae Arnicae - Tincture of Arnica (20 per cent.). -

The root of Arnica montana and all its preparations official in the Pharmacopoeia of 1890, have been dropped from the Pharmacopoeia of 1900.

Physiological Action. - Externally and Locally. - The local action of both the root and flowers is irritant, that of the latter being the more powerful. Occasionally tincture of arnica flowers produces marked inflammation of the skin, resembling erysipelas.

Internally. - The internal effects of arnica are as yet imperfectly understood, it being difficult to assign the drug to its proper group.

Digestive System. - Small doses slightly stimulate the digestive apparatus. Large amounts produce nausea, vomiting, and diarrhea of a choleraic character.

Circulatory System. - Small doses stimulate the heart and increase arterial pressure; full or large doses retard the pulse and depress the circulation.

Nervous System. - Large amounts cause headache, with great depression of the nerve-centers. Toxic amounts occasion motor and sensory paralysis, coma, at times convulsions, collapse, and death.

Respiratory System. - The respiration is slowed, although under small doses there may be temporary acceleration.

Absorption and Elimination. - The active principle of arnica diffuses readily into the blood, the drug being eliminated chiefly by the kidneys, though the skin shares in the excretory process.

Temperature. - Large doses cause a reduction of temperature.

Untoward Action. - The topical application of arnica may cause in susceptible persons violent cutaneous inflammation and the production of pustules, or even distinct bullae, attended with marked constitutional symptoms. When taken internally the drug occasions a sensation of burning in the mouth and throat, violent pain in the stomach, tenesmus, and choleraic diarrhea, intense headache, and dizziness.

Poisoning. - In addition to the above-named symptoms there are great cardiac depression, decided muscular weakness, slow and shallow respiration, paralysis of the nervous system, and death resulting from collapse.

Treatment of Poisoning. - The treatment should be much the same as that prescribed under Aconite. Atropine is probably the best physiological antidote.

Therapeutics. - Externally and Locally. - Arnica enjoys a wide reputation as a remedy for the relief of bruises, sprains, and external inflammations generally. It is highly probable that its efficiency is due in part to a slight counterirritant effect, and to the alcohol contained in the mixtures. It has been recommended also as a topical application in myalgic rheumatism. The local application of the tincture causes the rapid disappearance of ecchymoscs. Equal parts of tincture of arnica and glycerin, diluted with water, have been recommended as a stimulant in inflammation of the mucous membrane of the mouth.

Internally arnica is not a very popular remedy.

Contraindications. - Externally when there exists any acute skin disease; internally in cases of inflammation of the gastrointestinal tract, fatty or valvular disease of the heart, and in all asthmatic conditions.

Administration. - The tincture of arnica is the form generally preferred for external and internal use. In applying any preparation externally the susceptibility to the irritating properties of the drug peculiar to certain persons should be remembered.