Viscum. Mistletoe.
Mistletoe is an evergreen, dioecious parasite, Viscum album, Linn. (N.O. Loranthaceae), which grows on the branches of deciduous trees, chiefly the apple, poplar, plum, etc., forming a pendant bush from 6 to 15 decimetres (2 to 5 feet) in diameter. The branches are numerous and forked, and covered with a smooth bark of a yellowish-green colour; the leaves are tongue-shaped, entire, opposite, coriaceous, fleshy, very shortly petiolate, and without distinct veins. The fruit is a globular, whitish berry, with a viscid pulp, and appears in winter. The root insinuates its fibres into the woody substance of the tree upon which it grows, and thus derives some of its nourishment from the host. Various preparations of the plant are used in medicine, chiefly of the young twigs and leaves. The leaves, when dried, lose 58 to 60 percent. in weight. Guipsine is a proprietary preparation stated to contain the active principlesof mistletoe.
Constituents.—Mistletoe contains a volatile alkaloid, two saponins, mucilage, sugar, a crystallisable acid, a fixed oil, resin, an odorous principle, tannin, various salts and also viscin, a substance which is mainly developed by fermentation, and becomes a yellowish, sticky, resinous mass. The plant yields about 23 per cent. of extractive matter to water.
Action and Uses.—Mistletoe was at one time supposed to have properties resembling digitalis, and has been used in the treatment of cardiac and other dropsies; also in albuminuria and arteriosclerosis. In reality it has a depressant action on the heart, certainly it has no effect in any way resembling that of digitalis. It is said to lower arterial tension, but the clinical evidence in support of this is unconvincing. The berries are purgative and emetic, and are said to have emmenagogue and ecbolic properties when given in large doses. Its principal action is to depress the nervous system, especially the medulla. The extract is administered in pill form with or without tannin. An infusion or decoction, made by boiling 2 ounces of the bruised plant with 10 fluid ounces of water, may be given in tablespoonful doses several times daily. A liquid extract for hypodermic or intravenous injection is prepared in the same way as the extract, except that evaporation is stopped when the mixed liquids measure 50; sodium chloride, 0.35, is then added and the liquid filtered, after which the preparation is sterilised by heating to 120° in an autoclave for twenty minutes.
Dose of the leaves in powder.—1 to 4 grammes (15 to 60 grains).
PREPARATIONS.
- Extractum Visci, B.P.C.—EXTRACT OF MISTLETOE.
- May be prepared by macerating 10 of the coarsely powdered young shoots and leaves with 60 of boiling water for twelve hours; then straining, pressing, and twice macerating the residue with 30 of boiling water for twelve hours, afterwards filtering the mixed liquid, and evaporating to the consistence of a thick extract Dose.—10 to 15 decigrams (15 to 24 grains).
- Tinctura Visci, B.P.C.—TINCTURE OF MISTLETOE. 1 in 8.
- Dose.—3 to 6 decimils (0.3 to 0.6 milliliters) (5 to 10 minims).
