External

Antimonial compounds are powerful external irritants. The Liquor Antimonii Chloridi of the B. P., which is a solution of antimony chloride in hydrochloric acid is a severe caustic Tartar emetic produces a pustular eruption at the point of application.

Internal

Alimentary canal. - All compounds of antimony are powerful irritants, internally as well as externally; the action of tartar emetic is best known. The first result of swallowing this is vomiting. The early acts of vomiting are due to the direct action of the drug on the wall of the stomach, but it is quickly absorbed, and by its action on the medulla it also produces sickness, but this action is slight. It will produce vomiting when injected into the blood, partly by its action on the medulla - for it will act if the stomach is replaced by a bladder - but also because some of it is excreted into the stomach and intestines, and thus the vomiting is continued for some time. In large doses tartar emetic is irritant to the intestine. A round mass of metallic antimony was formerly known as the " family pill," because it could be repeatedly used as a laxative.

Heart

Antimony acts upon man as upon the lower animals. It is a powerful cardiac depressant, diminishing both the frequency and the force of the beat of the heart. Experiments on animals have shown that the final stoppage takes place in diastole, and that the chief action of antimony is that of a direct depressant to the cardiac muscle itself. Of course, the cardiac depression causes the arterial pressure to fall; but part of this effect is due to a coincident action upon some portion of the vaso-motor system; the probability being that antimony, by paralyzing the muscular coat of the arteries, relaxes them.

Respiration

Respiration is depressed, the movements become weaker, and inspiration is shortened, but expiration is prolonged. Finally, the pauses become very long and the movements very irregular. The cause of this is not known; probably it is very complex.

Nervous And Muscular Systems

Here also antimony acts as a powerful depressant, especially to the spinal cord, and to a less extent to the brain; hence moderate doses cause a feeling of languor, inaptitude for mental exertion, and sleepiness. Experiments on animals show that, after the administration of large doses of antimony, reflex movement is soon lost, and that this is due to a depressing effect on the sensory part of the spinal cord. This depressant influence is felt also in the muscles, and hence antimony will relieve spasm, but whether it does so by direct action on the muscles or by acting on the nervous system is doubtful.

Temperature

Moderate doses of antimony have little influence on the temperature, but large doses cause a considerable fall, due, no doubt, in the main to the circulatory depression, but, also, it is said, to a direct action in decreasing the amount of heat produced.

Excretion

Antimony is excreted by the urine, bile, sweat, bronchial secretion, milk, and particularly by the faeces. We have seen that part of its emetic effect is due to its excretion into the stomach. As it passes out by the bronchial mucous membrane it increases the amount of secretion, and thus acts as an expectorant. On the skin the action is that of a profuse diaphoretic. This is chiefly a secondary result of the depression of the circulation, but is possibly in part a direct local effect. In frogs the action on the skin is very like that of arsenic, but antimony softens rather than detaches the epidermis, which thus becomes a jelly-like mass. Being excreted in the bile, it aids its flow; therefore it is a cholagogue.

In passing through the kidneys it may be slightly diuretic, but this depends upon the amount of perspiration produced by it. If its use is continued for some time it will cause, like arsenic, fatty degeneration, especially of the liver, and abolition of the hepatic glycogenic function.