APOCYNUM CANNABINUM. — This is the root of the Apocynum Canna binum, or Canadian hemp. The plant is gray or brownish gray in color, with rather thick bark and porous spongy wood. It contains, besides tannic acid, gallic acid, and gum resin, a bitter prin ciple which is found in the market un der the name of "apocynin." This is an amorphous resinous substance, not a glucoside, easily soluble in alcohol and ether, and almost insoluble in water.
Apocynum itself is inodorous, and has a disagreeable, bitter taste.
Dose. — The powdered root may be given in doses varying from 5 to 30 grains. In small doses it acts as a bitter - tonic; in 10- to 15-grain doses it acts as a diaphoretic, diuretic, and laxative. In larger doses-15 to 30 grains—it very considerably irritates the gastro-intes tinal tract and gives rise to vomiting and diarrhoea.
Dose of the decoction (1 drachm to S ounces), 1 to 2 ounces daily; of the tincture (1 part to 10), 5 to 10 minims. The U. S. P. fluid extract, in doses of from 10 to 30 minims, is a valuable preparation.
Physiological Action.—Apocynum produces a very pronounced retardation of the pulse, with a very considerable enlargement of the pulse-wave and a marked rise of the blood-tension. The initial retardation of the heart is fol lowed by an acceleration of the cardiac action, while the arterial pressure as cends still farther. The cardiac retar dation (first stage) is caused by an irri tating action of the drug, both on the central and peripheral inhibitory appa ratuses. The subsequent acceleration (second stage) is not dependent upon anything like paralysis of the inhibitory 19 apparatus, since the injection of another dose of the infusion can again give rise to a retardation of the heart's work.
On the injection of a very large dose the two stages are followed by a third one, which is characterized by cardiac arhythmia, the appearance of Traube's waves, and a gradual fall of the blood pressure down to O. The rise of the blood-tension during the first and second stages is dependent not only upon the stimulation of the vasomotor centres in the medulla oblongata, but also (and that in a very considerable degree) upon the excitation of the spinal vasomotor centres. Moreover, the heart and blood vessels themselves take a certain active part in the causation of the rise. Both the central and peripheral vasodilatory apparatuses remain wholly intact. (So kaloff.) The physiological action of apocynum is clinically: To strengthen and tone up heart-action; to regulate markedly the irregular heart—not slowing the normal heart, nor increasing the blood-pressure, there being no contraction of the arteries. Its diuretic action is indirect and due to its "eardiokinetic" effect, and not through stimulation of the renal epi thelium. Decoctions of the drug cause mainly catharsis and ernesis. Dose of the tincture is 20 drops, increased to 30 drops thrice daily. T. S. Dabney (Thor. Gaz., vol. xxii, p. 730, '98).
Therapeutics.—The action of the root of the Apocynum Cannabinuin is similar to that of digitalis, without being cumu lative.