The term antipsychotic is used for any drug used to control the acute symptoms of schizophrenia, they are also used to prevent relapses and to diminish chronic symptoms. They can also combat the problems of mania. They are sometimes incorrectly referred to as major tranquilizers which is incorrect as they have no relationship to the anti-anxiety drugs.
The drugs interact on a wide range of neuroreceptors and often have antidopaminergic effects. The range of interacts produce many different adverse effects of extrapyramidal reactions, including acute dystonias, akathisia, rigidity and tremour and tardive dyskinesia as well as tachycardia, hypotension, impotence, lethargy, seizures and on and on. They are believed to control the symptoms of schizophrenia by blocking dopamine receptors.
Drugs used as antipsychotics include the three groups of phenothiazines, thioxanthenes, diphenylbutylpiperidines, substituted benzamides, ioxapine (tricyclic dibenzoxazepine), clozapine (dibenzodiazepine) and oxypertine.
The first antipsychotic was thorazine which was developed as a surgical anesthetic but was soon found to have therapeutic benefits to mental patients.
Anti-psychotics can be classified on a spectrum of low potency to high potency where potency refers to the ability of the drug to bind to dopamine receptors and not to the effectiveness of the drug. High potency antipsychotics such as Haldol typically have doses of a few milligrams and cause less sleepiness and calming effects than low potency antipsychotics such as thorazine which have dosages of several hundred milligrams.
Antipsychotics also can be classified as "typical" and "atypical." Typical antopsychotics include drugs which are related to those that have been used in clinical practice since the 1960's. Atypical antipsychotics, the first of which was clozapine, include a large number of new ones have entered practice since the 1990's. "Atypical antipsychotics" act on different neuroreceptors than the typical antipsychotics and have produces remarkable improvement in patients with which typical antipsychotics have not been of much benefit.