Hypnotic

hypnotic

a drug or agent that induces sleep

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hypnotic [hip′näd·ik]

(pharmacology)

A drug which induces sleep. Also known as somnificant; soporific.

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Hypnotic 

any one of a group of drugs that induce sleep. In large doses hypnotics bring on a state of anesthesia. The effect they produce is the result of their inhibitory action on various parts of the central nervous system.

Hypnotics include substances differing in chemical structure, for example, such barbituric-acid derivatives as barbital, phenobarbital, barbital sodium, barbamil, barpental, and cy-clo’oarbital, such piperidine derivatives as Doriden, and such aliphatic compounds as chloral hydrate, carbromal, and bromi-sovalum. Drugs from other pharmacological groups also help normalize sleep; these drugs include sedatives, for example, bromides and valerian preparations, and tranquilizers, for example, diazepam (Seduxen), nitrazepam (Eunoktin), and chlor-diazepozide (Elenium). By diminishing emotional excitement and relieving tension and restlessness, sedatives and tranquilizers facilitate the onset of deep sleep.

Hypnotics are used with a variety of sleep disorders. Preparations with longer action, such as barbital and phenobarbital, are prescribed when an individual can fall asleep easily but soon awakens. When the difficulty consists in falling asleep but subsequent sleep is normal, barbamil, sodium pentobarbital, and Doriden are used. The sleep induced by most hypnotics differs considerably from natural sleep because the physiological succession of sleep periods is disturbed, with certain phases being suppressed. Thus, although barbiturates make it easy to fall asleep, they inhibit paradoxical sleep. If taken for a long time, they inhibit the paradoxical phase only at the start of treatment. Suspending the use of a hypnotic may markedly lengthen paradoxical sleep, intensify insomnia, and bring on nightmares.

The anesthetic action of hypnotics is slight, but they can intensify the effect of such nonnarcotic analgesics as amidopyrine and analgin, which are used with neuralgia. Hypnotics have a tranquilizing effect when used in doses that do not induce sleep. In doses exceeding therapeutic doses they may poison the body, causing the inhibition of breathing, a drop in body temperature and arterial pressure, a slowing of the pulse, and coma. Poisonings caused by hypnotics are treated by a series of measures aimed at maintaining breathing and the activity of the cardiovascular system and rapidly eliminating the drug from the body.

The daily use of long-acting hypnotics causes them to accumulate in the body, resulting in constant sleepiness, mental depression, and motor disorders. Prolonged ingestion decreases the body’s sensitivity to a hypnotic (habituation), which results in an even larger dose being needed to achieve the required effect. Drug dependence may also result.

REFERENCES

Zakusov, V. V. Farmakologiia, 2nd ed. Moscow, 1966. Pages 67–79.
Vein, A. M., and N. A. Vlasov. “Khimiia i farmakologiia sna” (bibliographic survey). Farmakologiia i toksikologiia, 1971, no. 3, pp. 369–80.
Mashkovskii, M. D. Lekarstvennye sredstva, 7th ed., part 1. Moscow, 1972.

V. V. CHURIUKANOV