SEDATIVE-HYPNOTIC

Sedative-hypnotic drugs are used to reduce motor activity and promote relaxation, drowsiness, and sleep. The term is hyphenated because, by adjusting the does, the same group of drugs can be used to produce mild sedation (calming, relaxation) or sleepiness. Thus, the distinction between a sedative and a hypnotic (sleeping pill) is often a matter of dose—lower doses act as sedatives and higher doses promote sleep.

In some people, sedative-hypnotics can produce a paradoxical state of excitement and confusion. This tends to occur more frequently in the very young and older populations. Some of these drugs have the potential to be abused. Very high doses of most sedative-hypnotic drugs will produce general anesthesia and can depress respiration so much that breathing must be maintained artificially or death will occur. The benzodiazepines are an exception to this in that higher doses typically produce sleep and are far less likely to severely depress respiration.

One of the first agents to be added to the list of the classic sedatives (alcohol and opiates) was bromide, introduced in 1857 as a treatment of epilepsy. Chloral hydrate was introduced in 1869, and paraldehyde was first used in 1882. The barbiturates were introduced in the early 1900's and remained the dominant drugs for inducing sleep and sedation until the bezodiazepines were developed in the late 1950's and early 1060's. A number of miscellaneous non-barbiturate sedatives (ethchlorvynol, glutethimide, carbromal, methylparafynol, methprylon, methaqualone) were introduced in the 1940's and 1950's, and for a brief period rivaled the barbiturates in popularity, but their used declined rapidly along with the use of barbiturates. The bromides were recognized to have toxic properties, but they were still in use until the mid-twentieth century; chloral hydrate and paraldehyde were used well into the late 1970's and are still used in some places. Some drugs with other medical uses are prescribed as hypnotics, but the effectiveness of these substances remains to be proven in well-controlled clinical trials.

An advance in the development of sedative-hypnotics occurred with the discovery of non-benzodiazepine drugs that also act on the bensodiazepine receptor. Zolpidem and zaleplon are short acting hypnotics that demonstrate fewer side-effects and less tendency for rebound insomnia when they are discontinued, a common problem with the benzodiazepines. These drugs also demonstrate less abuse potential than many of the other sedative-hypnotics and little respiratory depression.

(See also: Abuse Liability of Drugs ; Drug Interactions and Alcohol ; Drug Types ; Suicide and Substance Abuse )

BIBLIOGRAPHY

Gilman, A. G., et al. (Eds.). (1996). Goodman and Gilman's the pharmacological basis of therapeutics, 9th ed. New York: Macmillan.

Nemeroff, C. B. & Schatsberg, A.F. (Eds.). (1998). The American psychiatric press textbook of psychopharmacology. Washington D.C.: American Psychiatric Press.

Scott E. Lukas

Revised by Nicholas DeMartinis