A group of major antipsychotic drugs, colloquially called ‘TRANQUILLISERS’, widely used to treat psychoses (see PSYCHOSIS). They can be divided into three main groups. Chlorpromazine, methotrimeprazine and promazine are examples of group 1, usually characterised by their sedative effects and moderate ANTIMUSCARINE and EXTRAPYRAMIDAL SYSTEM side-effects. Group 2 includes pericyazine, pipothiazine and thioridazine, which have moderate sedative effects but significant side-effects. Fluphenazine, perphenazine, prochlorperazine and trifluoperazine comprise group 3. Their sedative effects are less than for the other groups and they have little antimuscarinic action but marked extrapyramidal side-effects (involuntary movements such as tremor).
In the short term they are used to calm disturbed patients, whatever the underlying condition (which might have a physical or psychiatric basis). They also alleviate acute anxiety and some have antidepressant properties, while others worsen DEPRESSION (see also MENTAL ILLNESS). The choice of drug depends on the extent of sedation required and the susceptibility of the patient to extrapyramidal side-effects. The differences between the drugs, however, are less important than the variabilities in patients’ responses.