A combination of carbonic acid and ethylic ether. From a priori considerations, the distinguished pharmacologist of Strasburg, Professor Schmiedeberg, was led to the conclusion that these compounds of ethyl must have the hypnotic powers, to some extent, of the group. A careful investigation confirmed this view. Of these ethyl compounds, called urethans, he found that the carbamate of ethyl was the most satisfactory, and to this he gave the generic name of the group, urethan. He submitted this to a characteristically thorough examination, and was thus able to confirm his original conception of the physiological actions.

Properties

Urethan occurs in whitish crystals, is without odor, is tasteless, and insoluble in water. The dose is very unequal, for so much depends on the purpose in view, the age, character, and susceptibility of the patient. The dose may be stated as from five grains to a drachm or more. The best form in which to administer it is the compressed pellet, but the capsule, the wafer, or simple powder may be employed. It has been ascertained of late, that the best hypnotic action can be developed only by massive doses. Saundby, however, narrates two cases of insomnia in which two grains at a dose seems to have been sufficient for the purpose; but the general opinion is that from forty to eighty grains must be given to bring about a decided hypnotic action.

Urethan has no irritating effect on the stomach, and does not impair digestion. Although insoluble in water, the stomach juice dissolves it readily, and hence it promptly diffuses into the blood. Two results, apparently opposite in character, are produced in due order: the first impression is of a stimulant character, but very brief in duration; the next consists in diminution of action, slowing of circulation and respiration, decline of temperature, and weakening of the reflexes, which gradually lessen in promptness and finally disappear. With the onset of the depression stage, drowsiness comes on, tranquil sleep succeeds, and this physiological condition passes into coma and insensibility if the quantity administered be toxic. Urethan is not actively toxic, however, for Prof. Anrep maintains that so large a quantity as eight to twelve grammes ( 3 ij — 3 iij) can be taken by an adult, without causing danger-symptoms. By Jaksch, one gramme (15½ grs.) is held to be sufficient to cause sleep. Mairet and Combemale administered it in various forms of mental diseases, and thus ascertained how far its hypnotic power is influenced by the character of the case, the presence of pain, and other disturbing influences. Urethan is not an analgesic, and hence pain will prevent its hypnotic action. The excitement of mania, noises, and odd situations, may also prevent the hypnotic action. The most frequent cause of dissatisfaction is insufficient quantity, for then the desired action fails, and consequently the remedy is discredited.

Unpleasant after-effects do not occur unless stomachal troubles interfere, and headache, nausea, and vertigo are quite exceptional. When the conditions are favorable, sleep comes on in fifteen minutes to an hour, is quiet, and lasts from six to eight hours. When it is administered for many days in succession its power lessens, although the dose may be increased; but if stopped for a time, the susceptibility of the brain is restored, and then urethan can be resumed again.

Therapy

The therapeutical applications of urethan are based on its physiological properties. Schmiedeberg began the consideration of its actions for a priori reasons, and, these being confirmed, he extended his investigations to the physiological and therapeutical aspects of the subject. Its hypnotic powers, its influence over the reflexes, and its antipyretic action, were accurately mapped out by the great pharmacologist, so that now the value of the new agent is known, its limitations are defined, and the morbid states to which it is applicable clearly shown.

In general terms, urethan is a hypnotic which may be successfully used to procure quiet and sleep, when the conditions are favorable to its action. As a hypnotic, its position is similar, but not quite equal, to that of paraldehyde.

Urethan is antagonistic to strychnine, but only the largest doses, under the most favorable circumstances, will make it powerful enough. Being a moderator of reflex action, it may prove useful in epilepsy, chorea, spasm, and cramp. It is probable, also, that it may be beneficial in the spasmodic respiratory neuroses. By way of illustration, the experiences of Dr. Ferreira may be referred to here. Cases of epilepsy, of uraemic convulsions, of tetanus, and of delirium tremens, were all influenced favorably, but a distinctly curative effect was manifest in some of the epileptic subjects, and in the cases of delirium tremens. Urethan should have further trial in the treatment of epilepsy, especially in those nocturnal in occurrence.