American Hellebore. Indian Poke. Nat. Ord. Melanthaceae. Linn. Syst. Polygamia Moncia. Hab. North America.
Med. Prop. and Action. The rhizome or root closely resembles Veratrum Album (q. v.; in its physiological effects, though it differs from it in being destitute of any purgative property. In small medicinal doses it is a powerful arterial sedative, reducing the force and frequency of the pulse in a remarkable degree. In addition to this depressing effect on the arterial system, and often independently of it, it occasions nausea, together with a feeling of prostration and a sense of weakness, or want of due command in certain muscles. When carried so far as to produce nausea and vomiting, its depressing effects on the circulation and nervous system are often very remarkable. The pulse falls from 75 or 80 down to 35 or 40, and at the same time becomes small, feeble, and occasionally almost imperceptible. The surface is pale and covered with a cold sweat; the patient at the same time experiencing a sense of chilliness, and sometimes of tingling and numbness. Headache, vertigo, dimness of vision, with dilated pupils, faintness, a feeling of stiffness of certain muscles and a want of command over them, are other symptoms evincing the sedative operation of the medicine: these are sometimes so great as to become alarming. This depressing operation is attended with stimulation of the secretory functions; the salivary, pulmonary, biliary, and urinary secretions are increased, it is said, by doses insufficient to occasion nausea or vomiting, whilst during the existence of the latter condition the same effect is produced on the function of the skin. Excessive action of any kind is easily controlled by opiates and alcoholic stimulants. With regard to the emesis produced by this agent, it is worthy of remark that its operation is very tardy, three quarters of an hour or more often elapsing before this effect is produced. Locally applied, it is a powerful irritant. Its powder snuffed up into the nostrils excites long-continued and violent sneezing, and applied to the skin in a moist state produces redness and burning. The presence of Veratria in this root was detected by Mr. J. G. Richardson.* Its sedative action relative to other agents of the same class, is fully examined by Dr. Cutter. Compared with venesection, he remarks, it has the advantage of not impairing the quality of the blood by a direct withdrawal of a portion of its solid and fluid constituents, whilst at the same time it equally lessens the force of the circulation, and exerts a sedative influence on the nervous system. Compared with Digitalis, it is sure, prompt, and not cumulative. Compared with Antimony, its effects are not as permanent, but it does not seem to directly change the character of the blood, and it does not purge. No instance of fatal poisoning by it has been recorded; no doubt the vomiting produced is a great safeguard (Braithwaite).
* Sammtl. Media. Schriften, t. i. Ess. Mat. Med. and Therap., p.308.
The dose of the powdered root is gr. j. - gr. ij. every third hour, and may be-increased, if necessary, till it produce its physiological effects. In doses of gr. iv. - gr. vj., it generally acts as an emetic, but in this character it is very objectionable, from the prostration which accompanies its operation. The best form is the Tincture (vj. of the fresh root to Oj. of diluted Alcohol is advised by Dr. Osgood, or viij. of the dried root to Oj. of officinal Alcohol by Dr. Norwood). The dose of the latter, which is to be preferred, is gutt. vj. - viij. every three or four hours. On the development of any of its physiological effects, the dose should be diminished or the remedy discontinued, and if resumed it should be given in smaller doses. Its external application in ointments, decoction, &c., is inadvisable, from the liability of its absorption into the system.