Aconite

Aconitum

The tuber of Aconitum napellus Linné (Nat. Ord. Ranunculaceae). (U. S. P.) Racine (d'aconit, Fr.; Eisenhutknollen, Ger.

The Indian aconite-root, or bish, is supposed to be more powerful than the root of Aconitum napellus, and is preferred for the manufacture of aconitine (Flückiger and Hanbury).

Ectractum Aconiti Fluidum

Fluid extract of aconite. Dose, τη j—τηv.

Extractum Aconiti

Extract of aconite. Prepared from the leaves. Dose, gr. 1/6 to gr. ss.

Tinctura Aconiti

Tincture of aconite-root. Dose, τη j—τη v.

Composition

The principal alkaloid is aconitia or aconitinet which exists in two forms, crystalline and. amorphous, and forms with acids crystallizable salts. The crystalline form of aconitine is soluble in chloroform, ether, and alcohol. Aconite contains also another alkaloid which has received various designations—pseudo-aconitine, na-pelline, nepalline, etc., which is closely allied to aconitine, and is found in commerce under this name. It is but slightly soluble in chloroform, ether, and alcohol, and it exists also in two forms, crystalline and amorphous. Besides the foregoing, another base has been discovered, to which the name napelline has also been given (Hübsch-mann). This is an amorphous alkaloid, having strong basic properties, soluble in water, chloroform, and alcohol, but not soluble in ether. These basic substances are united with a peculiar acid—aconitic acid.

Antagonists and Incompatibles

Alcohol, ether, ammonia, turpentine, digitalis, heat, etc., antagonize the actions of aconite. In cases of poisoning, the stomach should be evacuated, stimulants administered by the stomach and rectum, and external warmth applied. Digitalis has been used with considerable advantage (Fothergill). The intra-venous injection of ammonia may be practiced, and artificial respiration resorted to. To overcome the depression of the heart's action, which is the capital point, the hypodermatic injection of atropine is indicated. As the chief danger consists in failure of the heart's action, the recumbent position should be strictly maintained.

Synergists

All the agents of this group increase the effects of aconite. Cold, fatigue, and all depressing emotions, are also synergistic.

Physiological Actions

A drop of tincture of aconite placed on the tongue excites a warm and pungent sensation, followed by persistent tingling and numbness. Prolonged contact with the skin causes similar effects upon the sensory nerves. During the medicinal administration of aconite in considerable doses, irritation and a sense of constriction of the fauces are experienced. Large medicinal doses produce gastric pain, nausea, and even vomiting. When the gastro-intestinal mucous membrane is in an irritable state, aconite impairs the appetite, hinders the digestion, and causes diarrhoea, and in the normal state of the membrane, increases its secretions and hastens the peristaltic movements.

The systemic effects of aconite follow within a half-hour after its administration. The number and force of the heart-beats are reduced, and the arterial tension is lowered. The action of the skin is increased, and a more abundant urinary discharge takes place. If the quantity has been a full medicinal dose, some muscular weakness, tingling in the tongue, lips, and extremities, are also experienced. The whole duration of the effect is about three hours. When a lethal dose is swallowed, the symptoms begin in from five minutes to a half-hour. In a medical student, who swallowed by mistake a tea-spoonful of the tincture of the root, the symptoms began after he had reached the college, having walked from his quarters—the time being about twenty minutes. He experienced an overpowering sense of fatigue in the lower extremities, and he felt, also, great muscular weakness. His eyesight became dim, the globes rather prominent, the pupils dilated. He experienced great dyspnoea, and his respirations were shallow and labored. The pulse was at first slow and small, and at last became imperceptible. The surface of the body, the tongue, and breath, were cold. The skin was covered with a profuse sweat. He was restless, anxious, and sighed frequently; but he had no stupor or convulsions. There were also decided numbness and tingling in the extremities, and in the tongue and lips. Tactile impressions were very faint, and the sense of pain was greatly reduced, so that he seemed almost unconscious of irritants. His temperature fell 2° Fahr. Under the use of heat, brandy, and ammonia, he revived in the course of six hours, and, on the following day, although weak, there were no indications of the effects of the poison.

Aconite affects the sensory nerves before the motor. It paralyzes first the end-organs, next the nerve-trunks, and finally the centers of sensation in the cord. Aconite also impairs the reflex function of the spinal cord; but this effect is, doubtless, secondary to the sensory paralysis. The power of voluntary movement continues after the cessation of the reflex functions; but it is finally lost. The arrest of motility is due to the action of the poison on the motor centers of the cord, and subsequently on the nerve-trunks.

Aconite, applied directly to the heart, lessens the number and force of its beats, and finally arrests its action in the diastole. The cardiac muscle, after the cessation of its movements, does not respond to galvanic excitation. Aconite lowers the arterial pressure, as well as lessens the force of the heart-beat. From these facts it may be concluded that it is a direct cardiac poison, affecting its ganglia and muscle, and also a sedative to the vasor-motor nervous system. It is also a respiratory poison, in virtue of its paralyzing action on the muscles of respiration; but the action of the heart ceases before the respiratory movements.

Aconite increases elimination by the skin and kidneys. With increased discharge of water, there takes place, also, increased excretion of solids.