Chlorpromazine (CPZ), marketed under the brand names Thorazine and Largactil among others, is an antipsychotic medication. It is primarily used to treat psychotic disorders such as schizophrenia. Other uses include the treatment of bipolar disorder, severe behavioral problems in children including those with attention deficit hyperactivity disorder, nausea and vomiting, anxiety before surgery, and hiccups that do not improve following other measures. It can be given by mouth, by injection into a muscle, or into a vein.Chlorpromazine is in the typical antipsychotic class, and, chemically, is one of the phenothiazines. Its mechanism of action is not entirely clear but believed to be related to its ability as a dopamine antagonist. It also has anti-serotonergic and antihistaminergic properties.Common side effects include movement problems, sleepiness, dry mouth, low blood pressure upon standing, and increased weight. Serious side effects may include the potentially permanent movement disorder tardive dyskinesia, neuroleptic malignant syndrome, severe lowering of the seizure threshold, and low white blood cell levels. In older people with psychosis as a result of dementia it may increase the risk of death. It is unclear if it is safe for use in pregnancy.Chlorpromazine was developed in 1950 and was the first antipsychotic on the market. It is on the World Health Organizations List of Essential Medicines. Its introduction has been labeled as one of the great advances in the history of psychiatry. It is available as a generic medication.
In December 1950, the chemist Paul Charpentier produced a series of compounds that included RP4560 or chlorpromazine. Simone Courvoisier conducted behavioural tests and found chlorpromazine produced indifference to aversive stimuli in rats.Chlorpromazine was distributed for testing to physicians between April and August 1951. Laborit trialled the medicine on at the Val-de-Grâce military hospital in Paris, using it as an anaesthetic booster in intravenous doses of 50 to 100 mg on surgery patients and confirming it as the best drug to date in calming and reducing shock, with patients reporting improved well being afterwards. He also noted its hypothermic effect and suggested it may induce artificial hibernation. Laborit thought this would allow the body to better tolerate major surgery by reducing shock, a novel idea at the time. Known colloquially as "Laborits drug", chlorpromazine was released onto the market in 1953 by Rhône-Poulenc and given the trade name Largactil, derived from large "broad" and acti* "activity".Following on, Laborit considered whether chlorpromazine may have a role in managing patients with severe burns, Raynauds phenomenon, or psychiatric disorders. At the Villejuif Mental Hospital in November 1951, he and Montassut administered an intravenous dose to psychiatrist Cornelia Quarti who was acting as a volunteer. Quarti noted the indifference, but fainted upon getting up to go to the toilet, and so further testing was discontinued (orthostatic hypotension is a known side effect of chlorpromazine). Despite this, Laborit continued to push for testing in psychiatric patients during early 1952.