Antihistamines are drugs used to relieve the symptoms of allergies caused by histamine, an amino acid derivative found throughout the body. Histamine was first recognized and suggested as the cause of allergic reactions by Henry Dale (1875-1968) and Patrick Playfair Laidlaw (1881-1940) in 1910. By 1932 histamines were confirmed as causative agents in allergic response. Researchers then sought to find agents that could counteract the effects of histamines.
A Swiss-Italian pharmacologist, Daniele Bovet, of the Pasteur Institute in Paris, France, focused on this problem in 1936. Since histamine is extremely toxic except when introduced to the body by absorption through the intestine, Bovet reasoned that histamine must normally exist in the body in combination with a neutralizing substance. Only "free" histamine would produce allergic symptoms, so an antagonist (an substance that opposes or resists the action of another substance) to this free histamine had to be found. However, histamine has no naturally occurring antagonist. Because the two hormones adrenaline and acetylcholine are structurally similar to histamine, Bovet investigated two groups of substances called sympatholitics and parasympatholitics, which block the effects of adrenaline and acetylcholine, hoping that some element of these compounds would also prove to be antagonistic to histamine. This approach proved fruitful, and in 1937 Bovet and his research student Anne-Marie Staub succeeded in synthesizing the first antihistamine, thymoxydiethylamine.
This was too toxic to use in humans, however, so from 1937 to 1941 Bovet conducted thousands of experiments to produce a usable antihistamine. He succeeded with pyrilamine, which was introduced to the public in 1944.
Bovet's work laid the structural basis for safe, effective synthesis of antihistamines. Bernard N. Halpern, a French research biologist and physician, described the use of phenbenzamine in 1942. In 1943 a young lecturer at the University of Cincinnati named George Rieveschl developed diphenhydramine. Marketed to millions by Parke-Davis as Benedryl, this antihistamine made Rieveschl a wealthy man. Once developed, antihistamines became wildly popular, promoted by rival drug companies for relief of symptoms of the common cold as well as of allergies. Side effects of antihistamines include high blood pressure and sedation. Usually taken orally, antihistamine nasa sprays designed to work faster by going directly to the nasal passages have also been developed. Another function of these drugs was discovered by accident in 1947 when an allergy patient took an antihistamine called Dramamine and unexpectedly found that, for the first time in years, she did not suffer from motion sickness when she rode a streetcar.
This is the complete article, containing 408 words
(approx. 1 page at 300 words per page).
