The seeds of Strychnos nux-vomica, an East Indian tree. The active principle is the alkaloid, strychnine, an important poison. Two other important principles are brucine and igasuric acid. Brucine is of half the strength of strychnine.

Physiological Actions

Nux vomica in medicinal doses is tonic, with the qualities of bitter stomachics; it increases appetite, aids digestion, and promotes peristalsis. It also stimulates respiration, the heart, and vaso-motor centres. These actions are largely due to the presence and influence of strychnine. Strychnine enters the system rapidly, especially the nervous tissues, on which its pre-eminent action, that of a motor excitant, is shown. It is excreted very slowly, not disappearing from the tissues for several days, and therefore accumulates in the system when given in continuous doses, even small ones.

The power of strychnine in regard to the nervous system is exerted on the motor centres of the spinal cord and all the important nerve centres in the medulla.

The first constitutional symptoms are a feeling of restlessness, with slight trembling of the extremities.

After a full dose (gr. 1/10), there are noticeable muscular twitching and jerking of the limbs, slight stiffness of the jaw, a tense feeling about the head, stricture of the throat and chest, shuddering, and a feeling of anxiety.

Symptoms Of Poisoning

After poisonous doses (gr. 1/2 for an adult), violent symptoms come on very suddenly, probably within fifteen minutes, with tonic convulsions resembling the spasm of tetanus. The legs are rigid, extended, and the feet averted, or the body may be bent backward until the head and heels meet (opisthotonos). The arms are bent, and hands clinched; the eyes open and staring. The corners of the mouth are drawn up by the muscles in a mechanical grin, the "risus sar-donicus," which gives a ghastly unmeaning expression, and the face - at first pale - presently becomes livid from asphyxia.

Between the paroxysms there is a period of relaxation and quiet, but the slightest sound, or touch, or breath of air brings on the spasms again instantly by reflex action, owing to the condition of intense irritability.

In cases which terminate fatally, the spasms succeed each other quickly, and death takes place in two or three hours from paralysis of the respiratory muscles. The mind usually remains clear up to the last. Sometimes asphyxia produces insensibility just before death.

Strychnine convulsions resemble tetanic and hysterical convulsions in some particulars. The special points of difference are as follows: