Amyl nitrite is produced by distilling nitric acid with amylic alcohol (fusel oil), sulphuric acid, and copper, and purifying with alkalies by various intricate processes. An ethereal liquid of yellow color and fruity odor.
It is given by inhalation usually. The vapor enters the blood through the lungs with extreme rapidity, reaching the tissues and producing its characteristic effects almost instantaneously.
Amyl nitrite is a motor depressant. Its leading physiological action is upon the spinal cord and the circulation, other effects being secondary. The motor centres in the cord are directly and strongly depressed, and a similar but less powerful action is exerted on the motor nerves and muscles. The sensory nerves are but little affected.
Two effects are produced on the circulation. First, the muscular walls of the arteries are paralyzed; the vessels dilate, and the blood pressure falls. Second, by this reduction of the blood pressure the resistance which was met by the left ventricle in discharging its contents disappears, with consequent relief to the heart, which has at once less work to do, with the same, or increased, strength to do it. The heart-beats are increased in number - not always in force, - and the depression of the inhibitory apparatus gives the beats an energetic and thumping character.
In this way amyl nitrite acts as a heart stimulant, not by actually strengthening the heart itself, but by clearing away obstructions to a free circulation which increased the work of the heart and exhausted it by compelling it to put forth abnormal exertions.
From 2 to 5 drops, inhaled, will give this result, with the attendant symptoms of fulness and throbbing of the head, amounting sometimes to severe pain.
If inhalation is carried beyond this there will be vertigo; flushing of the face, with visible pulsation of the carotids; deep, labored respiration; tingling of the surface; dilatation of the pupils; restlessness and anxiety. These symptoms disappear rapidly on the withdrawal of the drug, and the heart-beats fall to normal.
It is stated that all objects look yellow to one fully under the influence of amyl nitrite.
Larger doses increase all these symptoms in severity, to the point of grave depression, with cold extremities; heavy, clammy perspiration; slow, almost imperceptible pulse; irregular respirations; and severe persistent headache. There may sometimes be convulsions. Toxic doses paralyze the heart and respiratory centres. In cases of poisoning by amyl nitrite all the blood of the body becomes a uniform hue, which is described as being nearer a chocolate color than ordinary venous blood.
The poisonous dose is not certainly known. A dessert-spoonful taken internally has been recovered from, by the aid of emetics, and hypodermically ʒ ii. have been given in an hour and a half without unpleasant symptoms.
In giving inhalations of amyl nitrite, from 1 to 3 drops are placed on a handkerchief, or piece of lint or cotton, held near the nose, and withdrawn as soon as fulness in the head or flushing of the face is produced. The symptoms usually are a little more prominent for a moment or two after the drug has been withdrawn. It has been given hypodermically and also by mouth. In the latter way the dose is e i. - ii. on sugar. Amyl nitrite is inflammable.
Amyl nitrite escapes by the kidneys. The urine is increased in amount and in acidity, and may sometimes contain sugar.