In 1952, Laborit was instrumental in the development of the drug chlorpromazine, published his findings, and convinced three psychiatrists to test it on a patient, resulting in great success.

Laborit was recognized for his work, but as a surgeon searching for an anesthetic, he came to be at odds with psychiatrists who made their own discoveries and competing claims.

[1] During World War II he was stationed on the torpedo boat Sirocco, where he witnessed the evacuation of the Dunkerque, and then was sunk by the Germans.

With Pierre Huguenard, Laborit invented the lytic cocktail, a combination of drugs that could be given to patients to reduce the shock and stress they experienced during and after surgery.

Huguenard had success with a combination of promethazine and pethidine, at the time under the trade names Diparcol and Dolossal, and told Laborit of his finding.

Laborit suggested to Rhône-Poulenc (a pharmaceutical company that became Sanofi) that they create antihistamines that optimized stabilization of the central nervous system.

[6] There, chemist Paul Charpentier headed a group trying to improve on the existing drug diphenhydramine (Benadryl, Dramamine, U.S. Sominex).

[3] Simone Courvoisier tested the series on laboratory rats and discovered that RP 4560 (chlorinated promazine, later known as chlorpromazine) could reverse the effects of epinephrine and could induce a state of apathy or indifference.

"[9] Immediately following its synthesis at Rhône-Poulenc in December 1951, Laborit requested a sample of 4560 RP to test for the purpose of reducing shock in injured soldiers.

[10] His observation that people treated with this drug showed reduced interest in their surroundings led him to suggest the first test of antipsychotics by Hamon, Paraire and Velluz.

A 24-year-old patient with mania was released from Val-de-Grâce and ready "to resume a normal life" after 20 days treatment with chlorpromazine and barbiturates.

"[3][nb 2] Laborit shared the prestigious Lasker-DeBakey Clinical Medical Research Award in 1957 with Pierre Deniker and Heinz Lehmann for contributions towards the general use of chlorpromazine.

He received the Lasker-DeBakey Clinical Medical Research Award which he shared in 1957, after traveling to the United States on behalf of Rhône-Poulenc.