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When did researchers first discover compounds that protected animals against histamine and anaphylactic shock?

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antihistamines, including Benadryl — antihistamine Antihistamines such as Benadryl (diphenhydramine) and Claritin (loratadine) can be purchased without prescriptions. Both of those agents act by blocking H₁ receptors. However, whereas Benadryl binds to those receptors in the central nervous system (CNS), causing drowsiness, Claritin does not readily enter the CNS and thus does not normally cause drowsiness.

French researchers first discovered compounds that protected animals against the lethal effects of histamine and anaphylactic shock in approximately 1937. This breakthrough, led by the pharmacologist Daniel Bovet, marked the development of the first antihistamine substances.12