OLDER SEDATIVE–HYPNOTIC AND ANXIOLYTIC AGENTS
Before the introduction of the benzodiazepines, a num-ber of drugs from different chemical and pharmacolog-ical classes were used in the treatment of anxiety and insomnia. However, these drugs are more toxic and pro-duce more serious side effects than do the benzodi-azepines. Many also have significant abuse potential. Consequently, most of these compounds are no longer widely used. These drugs include the barbiturates (e.g., pentobarbital, amobarbital), carbamates (e.g., meproba-mate), piperidinediones (e.g., glutethimide), and alco-hols (e.g., ethchlorvynol).
Chloral hydrate (Noctec, Somnos) was developed in the late 1800s and is still used as a sedative–hypnotic agent. It is a hydrated aldehyde with a disagreeable smell and taste that is rapidly reduced in vivo to trichloroethanol, which is considered to be the active metabolite. It produces a high incidence of gastric irri-tation and allergic responses, occasionally causes car-diac arrhythmias, and is unreliable in patients with liver damage.