Hexobarbital is a barbiturate

Barbiturate

Barbiturates are drugs that act as central nervous system depressants, and can therefore produce a wide spectrum of effects, from mild sedation to total anesthesia. They are also effective as anxiolytics, as hypnotics, and as anticonvulsants...

 derivative having hypnotic

Hypnotic

Hypnotic drugs are a class of psychoactives whose primary function is to induce sleep and to be used in the treatment of insomnia and in surgical anesthesia...

 and sedative

Sedative

A sedative or tranquilizer is a substance that induces sedation by reducing irritability or excitement....

 effects. It was used in the 1940s-1950s as an agent for inducing anesthesia

Anesthesia

Anesthesia, or anaesthesia , traditionally meant the condition of having sensation blocked or temporarily taken away...

 for surgery and has a relatively fast onset of effects and short duration of action. However it can be difficult to control the depth of anesthesia with hexobarbital which makes it quite dangerous, and it has now been replaced by safer drugs in human medicine, usually thiopental would be the barbiturate of choice for this application these days. Hexobarbital was also marketed as a rapid-acting sleeping medication with short duration (tradenames: Citopan, Evipan and others, usually in 250 mg strength tablets). Hexobarbital is still used in some scientific research.