The original antipsychotic drugs were happened upon largely by chance and then tested for their effectiveness. The first, chlorpromazine, was developed as a surgical anesthetic. It was first used on psychiatric patients because of its powerful calming effect; at the time it was regarded as a non-permanent "pharmacological lobotomy". Lobotomy at the time was used to treat many behavioral disorders, including psychosis, although its effect was to markedly reduce behavior and mental functioning of all types. However, chlorpromazine proved to reduce the effects of psychosis in a more effective and specific manner than lobotomy, even though it was known to be capable of causing severe sedation. The underlying neurochemistry involved has since been studied in detail, and subsequent antipsychotic drugs have been developed by rational drug design.
The discovery of chlorpromazine's psychoactive effects in 1952 led to further research that resulted in the development of antidepressants, anxiolytics, and the majority of other drugs now used in the management of psychiatric conditions. In 1952, Henri Laborit described chlorpromazine only as inducing indifference towards what was happening around them in nonpsychotic, nonmanic patients, and Jean Delay and Pierre Deniker described it as controlling manic or psychotic agitation. The former claimed to have discovered a treatment for agitation in anyone, and the latter team claimed to have discovered a treatment for psychotic illness.
Until the 1970s there was considerable debate within psychiatry on the most appropriate term to use to describe the new drugs. In the late 1950s the most widely used term was "neuroleptic", followed by "major tranquilizer" and then "ataraxic". The first recorded use of the term tranquilizer dates from the early nineteenth century. In 1953 Frederik F. Yonkman, a chemist at the Swiss-based Cibapharmaceutical company, first used the term tranquilizer to differentiate reserpine from the older sedatives.
The word neuroleptic was coined in 1955 by Delay and Deniker after their discovery (1952) of the antipsychotic effects of chlorpromazine. It is derived from the Greek: "νεῦρον" (neuron, originally meaning "sinew" but today referring to the nerves) and "λαμβάνω" (lambanō, meaning "take hold of"). Thus, the word means taking hold of one's nerves. It was often taken to refer also to common side effects such as reduced activity in general, as well as lethargy and impaired motor control. Although these effects are unpleasant and in some cases harmful, they were at one time, along with akathisia, considered a reliable sign that the drug was working.
The term "ataraxy" was coined by the neurologist Howard Fabing and the classicist Alister Cameron to describe the observed effect of psychic indifference and detachment in patients treated with chlorpromazine. This term derived from the Greek adjective "ἀτάρακτος" (ataraktos), which means "not disturbed, not excited, without confusion, steady, calm". In the use of the terms "tranquilizer" and "ataractic", medical practitioners distinguished between the "major tranquilizers" or "major ataractics", which referred to drugs used to treat psychoses, and the "minor tranquilizers" or "minor ataractics", which referred to drugs used to treat neuroses.
While popular during the 1950s, these terms are infrequently used today. They are being abandoned in favor of "antipsychotic", which refers to the drug's desired effects. Today, "minor tranquilizer" can refer to anxiolytic and/or hypnotic drugs such as the benzodiazepines and nonbenzodiazepines, which are useful as generally short-term management for insomnia together with cognitive behavioral therapy for insomnia. They are potentially addictive sedatives.
Antipsychotics are broadly divided into two groups, the typical or first-generation antipsychotics and the atypical or second-generation antipsychotics. The difference between first- and second-generation antipsychotics is a subject of debate. The second-generation antipsychotics are generally distinguishable by the presence of 5HT2A receptor antagonism and a corresponding lower propensity for extrapyramidal side effects compared to first-generation antipsychotics.
