Sedative-hypnotics currently used drugs

A class of sedative/hypnotic type drug that exert their effects through the benzodiazepine binding site on GABAa receptors. The class consists both of molecules that contain the benzodiazepine moiety, for example diazepam, lorazepam and flunitrazepam, and the newer, non-benzodiazepine compounds such as zolpidem, zopiclone, indiplon and zaleplon. BzRAs are primarily used for the treatment of anxiety, insomnia and to elicit varying levels of sedation. The wide selection of compounds currently available affords the prescribing clinician extensive options in terms of relative efficacies and durations of action. 

Allgulander, C. History and current status of sedative-hypnotic drug use and abuse. Acta Psychiatr. Scand. 73, 465-478, 1986. 

Historically the first sedative hypnotics to be introduced were the bromides in the mid 19th century, shortly followed by chloral hydrate, paraldehyde and urethane. It was not until the early years of this century that the first barbiturate, sodium barbitone, was developed and this was shortly followed by over 50 analogues, all with essentially similar pharmacological properties. The major breakthrough in the development of selective, relatively non-toxic sedative hypnotics followed the introduction of chlordiazepoxide in 1961. Most of the benzodiazepines in current use have been selected for their high anxiolytic potency relative to their central depressant effects. Because of their considerable safety, the benzodiazepines have now largely replaced the barbiturates and the alcohols, such as chloral hydrate and trichloroethanol, as the drugs of choice in the treatment of insomnia. 

The elimination half-lives of a number of commonly used hypnotics are shown in Table 10.1. It should be noted that many of the drugs in current use have active metabolites which considerably prolong the duration of their pharmacological effect. This is particularly true for the elderly patient in whom the half-life of the hypnotic is prolonged due to decreased metabolism and renal clearance such individuals are also more sensitive to the sedative effects of any psychotropic medication. 

As noted, the barbiturates once were used extensively as sedative-hypnotic drugs, but except for certain specialized uses they now have been replaced by the safer benzodiazepines. Short-acting barbiturates still are used to produce anesthesia. Other current uses include emergency treatment of convulsions and prevention of seizures in persons with certain types of epilepsy (Perrine, 1996). 

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