Non-sedating antihistamines

History

The first H₁ receptor antagonists were discovered in the 1930s and were marketed in the 1940s. Piperoxan was discovered in 1933 and was the first compound with antihistamine effects to be identified. Piperoxan and its analogues were too toxic to be used in humans. Phenbenzamine (Antergan) was the first clinically useful antihistamine and was introduced for medical use in 1942. Subsequently, many other antihistamines were developed and marketed. Diphenhydramine (Benadryl) was synthesized in 1943, tripelennamine (Pyribenzamine) was patented in 1946, and promethazine (Phenergan) was synthesized in 1947 and launched in 1949. By 1950, at least 20 antihistamines had been marketed. Chlorphenamine (Piriton), a less sedating antihistamine, was synthesized in 1951, and hydroxyzine (Atarax, Vistaril), an antihistamine used specifically as a sedative and tranquilizer, was developed in 1956. The first non-sedating antihistamine was terfenadine (Seldane) and was developed in 1973. Subsequently, other non-sedating antihistamines like loratadine (Claritin), cetirizine (Zyrtec), and fexofenadine (Allegra) were developed and introduced.