Apocynum consists of the rhizome and root of Apocynum cannabinum, Linn. (N.O. Apocynaceae), and of other species of Apocynum, all being herbaceous plants growing in the United States and Canada. The drug is official in the U.S.P. The root occurs in long, cylindrical, simple or branched, often tortuous, pieces, from 5 to 10 millimetres thick, and of a grey or brownish-grey colour; they are longitudinally wrinkled, and transversely fissured at somewhat distant intervals. The smoothed section exhibits a thick, pale brownish-grey cortex, enclosing a large, yellowish wood. In the cortex numerous laticiferous vessels may be recognised by their brownish contents. The wood contains small vessels and numerous delicate medullary rays. The drug is inodorous, but has a disagreeable, very bitter taste. The roots of Apocynum androsaemifolium have sometimes been used for apocynum, they have a thicker bark than those of A. cannabinum, a white porous wood, and contain in the outer portion groups of stone cells, which can be detected by the phloroglucin test.
Constituents.—The chief constituent of apocynum is the crystalline lactone cynotoxin, melting-point about 170°, to which the digitalis-like action is due. The crystalline substance apocynin, melting-point 115°, which was formerly considered to be the active principle, is identical with acetovanillone, and has little action. Apocynum androsaemifolium contains apocyanamarin, which is probably identical with cynotoxin; also apocynin, and its glucoside androsin, ipuranol, the two phytosterols androsterol and homo-androsterol, and various fatty acids.
Action and Uses.—Apocynum belongs to the group of cardiac tonics, and has an action corresponding in the main with that of digitalis. It has been largely used in America, where it has been termed the "vegetable trocar," on account of its supposed efficiency in removing cardiac dropsy. It differs from digitalis in being much more irritant to the gastro-intestinal canal, even causing gastric ulcerations in large doses; and, after absorption, it constricts the vessels more, and therefore increases blood pressure. Apocynum is indicated in all conditions in which the use of digitalis appears advisable; it has no action on the kidneys except by increasing the efficiency of the heart. On the whole, it is better to avoid the use of this very irritant drug; and when it is desired to raise blood pressure more than can be effected by digitalis, squill should be preferred. The drug may be administered in powder, but it. is usually given as liquid extract or tincture.
Dose.—½ to 3 decigrams (1 to 5 grains).
- Fluidextractum Apocyni, U.S.P.—FLUIDEXTRACT OF APOCYNUM. Syn.—Extractum Apocyni Liquidum; Liquid Extract of Apocynum; Liquid Extract of Canadian Hemp.
- Apocynum, in No. 60 powder, 100.; glycerin, 10; alcohol, a sufficient quantity; distilled water, a sufficient quantity. The product should measure 100. Liquid extract of apocynum is a powerful cardiac tonic, belonging to the digitalis group; it is said to be especially valuable in dropsy and pleurisy with effusion, but it is very irritant to the gastro-intestinal canal. The extract is a constituent of some American nostrums. Average dose.—10 decimils (1 milliliter) (15 minims).
- Tinctura Apocyni, B.P.C.—TINCTURE OF APOCYNUM. 1 in 10. Syn.—Tincture of Canadian Hemp.
- Used as a tonic and diuretic in cardiac dropsy. Dose.—3 to 6 decimils (0.3 to 0.6 milliliters) (5 to 10 minims).