The chemical name of this remedy is dimethyloxy-quinizine, which is so unmanageable that it could hardly be brought into general use. The original discoverers and promoters of the new agent bethought themselves to name it antipyrin, which is at the same time a convenient designation, a trade title to protect the proprietary rights, and a word significant of the most important property possessed by the new remedy.

Preparations and Physiological Actions

Antipyrin is a whitish or grayish-white crystalline powder, slightly but not persistently bitter in taste, and is soluble in water in equal parts by weight. It has basic properties, and combines with acids to form salts. The dose is determined by the uses to which it is applied, and varies from five to sixty grains—the maximum employed to reduce fever-heat. When massive doses are given, it is better to divide into smaller sections, and administer at short intervals, that the impression may be made as a unit. Having ready solubility, it may be prescribed in a solution, or injected subcutaneously.

Antipyrin does not irritate the stomach, but is a stomachic tonic, and the appetite is increased rather than diminished. On the intestine it acts as an antiseptic, inhibits microbes, and thus prevents fermentative changes. It is probable that it increases secretion, and stimulates the intestinal peristalsis also.

Antipyrin diffuses into the blood promptly, and, when the quantity is sufficient, brings about important changes in its constitution; the corpuscles are altered in form, the haematin separated, and the whole mass of the blood assumes in consequence a chocolate tint. On the organs of circulation the first effect is excitant in character, but it is brief in duration; the heart-beat is quicker; there is a flush, and a subjective sensation of warmth. Then perspiration begins, and may be very profuse; the pulse lessens in frequency; a sense of chilliness or a chill accompanies the pallor of the surface, and the temperature declines from one to five degrees according to the nature of the seizure and the doses given. In some instances the decline in body-heat passes below normal, but this result is observed more frequently when some other of this antipyretic group is used. The decline of the febrile heat begins in ten to twenty minutes after the dose has been given, and it persists from an hour to sixteen hours or longer according to circumstances. The normal temperature of the body is not affected, how large soever are the doses administered.

Antipyrin appears to be free from one source of danger common to the germicide antipyretics—the profound depression, almost collapse, which comes on with the sweating and precedes the next exacerbation of the fever, and in fact ushers it in. Although antipyrin is free from this dangerous depression, as a rule, there occur in certain subjects, with the sweating, some cardiac weakness and irregularity, of an unpleasant character, and hence it can not be asserted that this member of the group is free from the dangers inseparable from the action of the others, but it is far less toxic.

Antipyrin rather lessens the reflexes, and it possesses some analgesic property corresponding to that of the class.

It is eliminated chiefly by the kidneys, and induces the changes in the urine characteristic of the group to which it belongs.

Therapy

Having been discovered by Knorr, the power to lessen febrile heat was first investigated by Filehne, Schmidt, Nau-nyn, Gerhardt, and others. It was soon ascertained that antipyrin is an effective remedy for fever, the best, up to the present time, for the relief for that symptom, but not possessed of any power to alter the morbid condition producing the feverish state. As Huchard has happily expressed it, "Antipyrin is an antipyretic, but not an anti-periodic." It has been proved to have special power to reduce the high temperature of tuberculosis. It does not act with equal advantage in all cases, and inattention to the proper mode of administration will impair its usefulness. The experience thus far gained has shown that a few full doses will have a more happy effect than numerous small doses; but in either case, the periods of apyrexia, especially the sweating stage, are not suitable, and if administered at these times there is danger of upsetting the stomach and increasing the cold sweat. Fifteen grains after the onset of the fever, and repeated two or three times in as many hours, according to necessity, is the best mode of giving it.

Although antipyrin is the most efficient antipyretic in cases of tuberculosis, it does not change existing morbid states. The reduction of temperature effected by it lasts six to twenty-four hours, according to the. quantity given, the susceptibility of the patients, and other circumstances, and when the elevated temperature comes on again it may continue for several days below the general level of the fever previously (Huchard).

The published experience in the great journals of professional opinion, in respect to the utility of antipyrin in typhoid, now constitutes a vast literature of itself, and we can utilize here only the epoch-making papers. That antipyrin is a safe and efficient antipyretic in typhoid is generally admitted, but no one takes the position that it has a curative effect, or that the reduction of temperature has any influence of a permanent character on the dangers or duration of the fever. In the condition of hyperpyrexia its timely administration has proved very beneficial.

In the symptomatic fevers, such as pneumonia, the action of antipyrin has not been favorable, although reduction of temperature is a very constant result of its administration. In no form of febrile disease has it been so efficient as in acute rheumatism, and here it maintains the first place as a remedy in this disease, unless the advent of salol shall consign it to the second place. In acute rheumatism it is superior to the salicylates, and to other remedies, unless salol prove more efficient. From fifteen to twenty grains, every three to six hours, will be required until the cessation of joint-pain and the disappearance of the swelling. Under the action of antipyrin, as has been the result from all other remedies, a tendency to relapse is observed in a proportion of the cases, and hence persistence is necessary in the use of the remedy for some days after the attack has apparently ceased, but the amount given should be slowly reduced.

Antipyrin has the same power to reduce temperature in the malarial as in other fevers, but no power to prevent paroxysms—no anti-periodic quality. Hence it can never be used successfully in intermittent and remittent fevers.

The antipyretic quality, which at the outset was supposed to he the one attribute of the chinoline derivatives, has proved to be less valuable than the analgesic property, which they all possess to a varying extent. When Filehne demonstrated the antipyretic actions, he did not pursue the investigations into the effects of antipyrin on the nervous system, and the clinical studies which followed immediately throughout Germany (Guttmann, Bielochowsky, Pibram, and others) were occupied with its influence over the temperature in the course of the more important fevers.

The remarkable relief afforded by antipyrin and other members of the group in acute rheumatism led to their use in cases of neuritis, sciatica, and some other painful diseases. We are indebted to Professors Lepine and Huchard more especially for demonstrating the influence exerted by these agents over certain painful affections. It seems quite clear that the relief given is in maladies due to central and peripheric lesions of the nerve apparatus—for example, the pains of locomotor ataxia, neuralgia of the fifth nerve associated with neuritis, and sciatica due to the same cause.

Affections of a painful character are amenable to the action of antipyrin in proportion to the rheumatic influence or diathesis dominating them. By subcutaneous injection, it has proved to be very effective in many painful affections that have their seat in the nerves.

The members of this group of remedies have the power to diminish the reflex function, and hence have been used in the various spasmodic affections, as epilepsy, chorea, etc., with a measure of success, but not in so great a degree as to become substitutes for other tried remedies.