This section is from the book "Materia Medica Pharmacy, Pharmacology And Therapeutics", by W. Hale White. Also available from Amazon: Materia Medica Pharmacy, Pharmacology And Therapeutics..
Arnica Flowers. The flower heads of Arnica montana Linne (nat. ord. Compositae). Synonym. - Leopardsbane.
Europe and Northern Asia; in mountainous districts.
Heads about 3 cm. broad, depressed-roundish, consisting of 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, having slender, spindle-shaped achenes, crowned by a hairy pappus. Odor feeble, aromatic; taste bitter and acrid.
l) Arnicin, an amorphous, yellow, acrid, bitter principle; easily soluble in Alcohol and Ether. (2) Volatile Oil. (3) Caprylic and Capronic Acids. (4) Resin. (5) Tannic acid. Dose, 10 to 20 gr.; .60 to 1.20 gm.
Arnica Flowers, 200; by percolation with Diluted Alcohol to 1000. Dose, 10 to 30 m.; .60 to 2.00 c.c.
The rhizome and roots of Arnica montana Linne (nat. ord. Compositae).
Rhizome about 5 cm. long, and 3 or 4 mm. thick; externally brown, rough from leaf-scars; 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. Resembling Arnica. - Valerian and Serpentaria, each having a characteristic odor; Veratrum Viride, having thicker rootlets.
The same as of the flowers.
Dose, 5 to 20 gr.; .30 to 1.20 gm.
1. Extractum Arnicae Radicis. - Extract of Arnica Root. By maceration and percolation with Diluted Alcohol, and evaporation. Extract of Arnica Root is used to make Emplastrum Arnicae. Dose, 5 to 10 gr.; .30 to .60 gm.
2. Extractum Arnicae Radicis Fluidum. - Fluid Extract of Arnica Root. By maceration and percolation with Alcohol and Water, and evaporation.
Dose, 5 to 20 m.; .30 to 1.20 c.c.
3. Tinctura Arnicae Radicis. - Tincture of Arnica Root. Arnica Root, 100; by maceration and percolation with Alcohol and Water to 1000.
Dose, 5 to 10 m.; .30 to .60 c.c.
4. Emplastrum Arnicae. - Arnica Plaster. Extract of Arnica Root, 330; resin plaster, 670.
The action of arnica is the same as that of volatile oils generally. Externally the tincture is used as an application to bruises, but it is very doubtful how far its good effects are owing to the alcohol and how far to any increase of cutaneous vascularity due to the volatile oil of the arnica.
It is rarely given internally, but in small doses it is a stomachic, a carminative, and a reflex stimulant, and in larger doses causes vomiting and purging. It is excreted by the kidneys and mucous membranes, and it has been credited with obscure effects on the central nervous system.