Amyl Nitris

Amyl Nitrite

Amyl nitrite. Nitrite d'amyle, Fr.; Amylnitrit, Ger.

Properties

A yellowish or reddish-yellow liquid, rather oily in consistence, very volatile, and having a peculiar and very diffusive ethereal odor. It is insoluble in water, but soluble in all proportions in alcohol, ether, chloroform, benzol and benzin. It has a neutral or a slightly acid reaction. It may contain, as impurities, nitric acid, amyl-nitric ether, amylvalerianic ether, and hydrocyanic acid. The specific gravity is ·877. Dose, τη ij—τη v, by inhalation or subcutaneously.

Antagonists

The actions of the nitrite of amyl are antagonized by all those agents which increase the functional activity of the spinal cord and sympathetic — as strychnine, brucine, picrotoxin, digitalis, ergot, belladonna, and, as McCullough has shown, it is an efficient remedy in chloral - poisoning. The opposing action of amyl nitrite and ergot has been demonstrated clinically by Dr. Fancourt Barnes, in cases of hour-glass contraction induced by ergot. This antagonism may not be available, owing to the difference in the rate at which they are diffused, to affect the system.

Synergists

All of the motor depressants increase the effects of the nitrite of amyl.

Physiological Actions

The following are the symptoms produced by nitrite of amyl when inhaled: acceleration of the action of the heart; sudden flushing of the face; dilatation of the arterioles in consequence of paresis of the muscular layer of these vessels; a sense of extreme fullness of the brain, with vertigo; fall in the blood-pressure; lowering of the temperature; complete resolution of the muscular system of animal life. The vapor of nitrite of amyl applied directly to the tissues—muscular or nervous—suspends or completely arrests functional activity. Circulating in the blood, it undoubtedly affects most the vaso-motor nervous system and unstriped muscular fiber.

The marked acceleration of the heart (Pick) is in part consecutive, doubtless, to the sudden dilatation of the arterioles, permitting such an increased quantity of the blood to enter these vessels as to require renewed effort on the part of the heart to supply it; in part also to the paretic state which it induces in the inhibitory apparatus. The great fall in the blood-pressure noted by Brunton, Wood, and Amez-Droz, is also due to dilatation of the arterioles, and consequent diminution of tension in the peripheral vascular system. Dilatation of the retinal vessels, when nitrite of amyl is inhaled, has been ascertained by ophthalmoscopic examination (Aldridge).

On the nervous system of animal life the nitrite of amyl acts as a depressant—impairing motility first, and, at the last, sensibility. It affects both the spinal cord and the nerves, lessening the sensibility to all forms of irritation, and diminishing the reflex functions. It also impairs the contractility of muscle. Death ensues from failure of respiration, and the cerebral functions are unaffected until carbonic-acid poisoning ensues.

Decided lowering of temperature is produced by the nitrite of amyl. This result is no doubt due to the action of this agent on the haemoglobin, whereby the carrying capacity of the red blood-globules of oxygen is lessened (Gamgee), metamorphosis of tissue is interfered with, and the generation of animal heat is diminished. A peculiar change ensues in the color of the blood as a result of the lessened oxygenation: all the blood of the body assumes a modified venous hue.

A curious fact has been noted by Hoffmann, viz. : the hypodermatic injection of lethal doses of nitrite of amyl produces in rabbits a temporary glycosuria.

Therapy

The applications of the nitrite of amyl in the treatment of disease have been deduced from a study of its physiological actions. It is especially indicated when morbid symptoms result from vaso-motor spasm. It has been shown that epileptic attacks may be warded off by the inhalation of nitrite of amyl at the beginning of the movement of the aura. Patients who have a distinct warning of the seizures should be constantly provided with a small quantity of this remedy in order to practice the inhalation whenever an attack is impending. The mechanism of the action is very simple: the vaso-motor spasm of the cerebral vessels, which is the initial symptom of an epileptic convulsion, is relaxed, and the vessels dilated by the nitrite of amyl.

By the timely inhalation of the nitrite, the cold stage of an ague may be aborted, but the hot stage is not modified in any way (Price, Ziegler). This power may be most serviceable in cases of pernicious intermittent, the danger of which consists in the extreme depression of the cold stage. The cardiac failure caused by chloral, chloroform, and other heart-poison, and the condition of sudden weakness which may ensue from various causes, in cases of fatty heart, are often remarkably relieved by the inhalation or hypodermatic injection of amyl nitrite.

An attack of migraine, of that form characterized by vaso-motor spasm (pallor of the face), may be quickly relieved and sometimes aborted by the inhalation of two or three drops of amyl nitrite

When there are redness of the face, injection of the conjunctivae, ana fullness of the cerebral vessels, this remedy is contraindicated. Cases of neuralgia of the fifth nerve, second division, have been cured by inhalation of amy], repeated from time to time as the pain required its administration.

Asthma, when purely spasmodic, is usually quickly checked by this remedy. The paroxysms of difficult breathing which accompany emphysema and cardiac disease are not relieved in this way; indeed, the author has known the most serious distress to be produced by the inhalation under these circumstances.

Exaltation of the reflex function of the spinal cord and muscular spasm are morbid states in which good results may be expected from inhalation of the nitrite of amyl. It has been used with success in tetanus. It should also be fairly tried in strychnine-poisoning and in hydrophobia. Michael has administered it in tinnitus aurium, a most obstinate and distressing condition, with comparatively good effects: of a group of thirty-three cases, nineteen were distinctly benefited.

Most signal relief has been obtained from the inhalation of amyl nitrite in angina pectoris. We owe this important suggestion and practice to Brunton, who had ascertained that when the paroxysm of angina pectoris occurs, a great rise of arterial tension takes place. When the pain, praecordial distress, and anxiety are felt, there should be no delay in the use of the remedy. Some cautions are, however, needed. It may be unsafe when advanced degeneration of the cerebral vessels exists (Anstie). Fatty degeneration of the heart, which is so frequently a cause or an accompaniment of angina pectoris, may also render the use of so powerful a paralyzer of doubtful expediency.

Dr. Mary Putnam Jacobi has found the inhalation of nitrite of amyl very serviceable in neuralgic dysmenorrhoea. As an antagonist to ergot, it may prove in a high degree useful, when ill effects are caused by this remedy. Thus, in a case of hour-glass contraction produced by ergot, the inhalation of amyl nitrite procured immediate relief. On theoretical grounds this agent was proposed for the relief of cholera asphyxia (Brunton, Gamgee), but the trials thus far made with it have demonstrated its inutility. Owing to the fact, shown by Gamgee, that nitrite of amyl combines with haemoglobin, Brunton proposes that this remedy, if given at all in cholera, must be administered by the stomach or by subcutaneous injection, and not by inhalation.

Repetition in the use of the nitrite of amyl diminishes its effects, and hence increasing doses are necessary when it is often employed in the same case.

Authorities referred to:

Aldridge, Dr. Charles. The West Riding Lunatic Asylum Medical Reports, vol. i, p. 97.

Amez-Droz, Dr. Archives de Physiologie Normale et Pathologique, 1873, p. 467.

Anstie, Dr. F. E. Transactions of Clinical Society. Lancet, March 5, 1870. Brunton, Dr. T. L. The British Medical Journal, July 13, 1872. Ibid. The Lancet, July 27, 1867.

Gamgee, Dr. Arthur. Philosophical Transactions, 1868, p. 589.

Haddon, Dr. John. Edinburgh Medical Journal, July, 1870, p. 45.

Jacobi, Dr. Mary Putnam. The Medical Record, New York, January 15, 1875.

Mitchell. Dr. S. Weir. The Philadelphia Medical Times, vol. v, p. 553.