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In 1933, the French pharmaceutical company Laboratoires Rhône-Poulenc began to search for new anti-histamines. In 1947, it synthesized promethazine , a phenothiazine derivative, which was found to have more pronounced sedative and antihistaminic effects than earlier drugs.  A year later, the French surgeon Pierre Huguenard used promethazine together with pethidine as part of a cocktail to induce relaxation and indifference in surgical patients. Another surgeon, Henri Laborit , believed the compound stabilized the central nervous system by causing "artificial hibernation", and described this state as "sedation without narcosis ". He suggested to Rhône-Poulenc that they develop a compound with better stabilizing properties.  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 "Laborit's 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 .