Chloral Hydrate

CHLORAL HYDRATE, Chloralum hydratum (Ф УП)(more precise Russian designation-hydrate of chloral), hydrate of trichloroacetaldehyde, CCl₃-CH(OH)₂, or CCl₃-CH(OH)₂; colorless transparent dry crystals with a slightly bitter, abrasive taste and a characteristic sharp aromatic odor, melting point (with rapid heating) at t°+57°. With slow heating, it melts at t° +47° to +49°, and at +51° begins to decompose into chloral and water. It dissolves 3 parts in 1 part water; in aqueous solution, gradual elimination of HCl occurs and the solution becomes acidic; for this reason, solutions of chloral hydrate are not prepared in advance; those prepared for dispensing by prescription must be kept cold. It easily dissolves in alcohol and ether, in 5 parts chloroform; only with heating does it dissolve in gasoline, petroleum ether, and fatty oils. When triturated with camphor, chloral hydrate forms an oily liquid. Chloral hydrate is stored with caution, in a dry place, in glassware with a well-fitting stopper. The property of chloral hydrate to induce sleep became known first in 1861 to Buchheim, who tested this remedy on himself and on patients, but it was introduced into medical practice only in 1869 by Libreich. Doses of chloral hydrate 0.5-1.0 (preferably in the form of an enema) are often sufficient to induce in the patient, 10-20 minutes after administration, a calm, normal-duration sleep, after which the patient awakens without special unpleasant sensations. During such sleep, cardiac activity, respiration, pupil constriction, and reflex state do not usually differ from those during normal sleep, and the patient can be easily awakened. Large doses of chloral hydrate (5.0) cause a deeper sleep with significant loss of consciousness, with diminished reflexes and sensitivity; respiration becomes less frequent, pulse is rare and of small volume, blood pressure drops sharply; duration of sleep in such cases is up to 10-15 hours; t° drops by 1-2°. After awakening, the patient feels unwell, has a headache, feels nauseous, and vomits. From even larger doses, reflexes and pain sensitivity disappear, t° drops by 3-4°, pulse becomes small and weak, respiration becomes rare and shallow, cyanosis appears, respiration may cease completely; cardiac contractions are sometimes observed after cessation of respiration. Asphyxial convulsions usually do not occur due to paralysis of the central nervous system. The action of chloral hydrate depends on its depressing and paralyzing effect on the central nervous system, on the sensitive or receptive functions of the brain, and on the motor areas of the cerebral cortex and spinal cord (Cushny). In the medulla oblongata, chloral hydrate depresses the vasomotor center most strongly, therefore blood vessels dilate, heat output increases and t° decreases; the latter is also facilitated by decreased muscle movements. The effect of chloral hydrate on a healthy heart becomes dangerous only with large doses, but on a diseased heart, chloral hydrate even in medium therapeutic doses can have a paralyzing effect. When inhaling vapors of chloral hydrate in animals, a state of anesthesia can occur, which in essence does not differ from chloroform anesthesia. From chloral hydrate, phenomena of excitement are sometimes observed in patients; more often such cases occur in nervous, hysterical, and alcoholic individuals. Metabolism under the influence of chloral hydrate decreases, the organism consumes less oxygen and less carbon dioxide is excreted. With chronic use of chloral hydrate, fatty degeneration of the liver, kidneys, and heart may be observed. Thus, the effect of chloral hydrate on the organism is similar to that of chloroform. Phenomena of idiosyncrasy to chloral hydrate are not uncommon. It is expressed by skin rashes of erythematous and eczematous character, resembling urticaria, sometimes with pustules, there may be asthmatic-type attacks, hyperemia of the conjunctiva, jaundice. Systematic prolonged use of chloral hydrate leads to habituation and to phenomena of chronic poisoning - chloralism, expressed by disorders of the nervous system and gastrointestinal tract, as well as the appearance of various skin rashes; at this time, mental disorders similar to alcoholic ones are common. Local action from chloral hydrate is strongly irritating. From chloral hydrate in substance or its concentrated solutions, inflammation and necrosis of tissues occur. Therefore, subcutaneous or intramuscular administration of chloral hydrate is not practiced. The antiseptic action of chloral hydrate is considerable. Chloral hydrate is excreted from the body with urine in the form of urochloralic acid - a paired compound of glucuronic acid with trichloroethyl alcohol, CCl₃CH₂OH, to which chloral is reduced in the body; part of chloral hydrate is excreted through the kidneys and gastric mucosa unchanged. The fact of formation of CCl₃CH₂OH led to the idea of using this alcohol, and in view of its extreme instability - tribromoethyl alcohol, for anesthesia (see Avertin). Acute poisoning with chloral hydrate and assistance in this case - see Poisoning. Therapeutically, chloral hydrate is indicated: 1) for all types of insomnia, however, for insomnia due to painful irritation, opium is more effective; 2) especially for insomnia in nervous and mentally ill patients; 3) as an anticonvulsant for tetanus, eclampsia, hydrophobia, chorea, persistent hiccups, poisoning with strychnine, cocaine, etc.; 4) as a sedative for delirium tremens, during manic attacks, during infectious psychoses. It is contraindicated in patients with cardiac obesity, with degeneration of the heart muscle, arteriosclerosis, etc.; with inflammatory and ulcerative processes in the gastrointestinal tract; in exhausted, weak individuals. External use of chloral hydrate is now rare: it can replace in the form of a compress the vesicant fly. The property of chloral hydrate to form liquid eutectics with camphor, salol, thymol, etc. at room temperature is used in the preparation of dental drops. Furthermore, chloral hydrate is used in mixtures for hair growth. If chloral hydrate cannot be given internally, the remedy is administered per rectum in the form of enemas. The highest single dose is 2.0, per day - 6.0 (ФУП) in aqueous solutions, to which mucilage is added to reduce the locally irritating action in the stomach and intestines; for the same purpose, after taking a mixture with chloral hydrate, the patient is advised to drink half a glass of water; to the mixture as a corrigens, some syrup (Sir. Cort. Aurantii) is added. Chloral hydrate cannot be prescribed in powders or capsules, so as not to cause irritation or even necrosis of the gastric mucosa. From chloral hydrate, chloroform for anesthesia is obtained industrially. Chloral hydrate is used in microscopy, technique for clearing plant specimens. Chloralose is a combination of chloral hydrate with glucose.

V. Nikolaev. Discovery of chloral hydrate in forensic chemical cases - see Chloroform, discovery in forensic chemical cases. In urine, chloral hydrate can sometimes be detected directly by the formation of chloroform when standing with alkali.