THE medicinal value of leaves and bark now known to contain salicylates was observed by Hippocrates, and numerous references to the analgesic properties of these plant materials may be found in the literature of the middle ages.1 In 1829, Leroux isolated the active ingredient of the willow bark and identified it as a glucoside, salicin. Salicylic acid was prepared from the latter by Piria in 1838, and the acetic acid ester, acetyl salicylic acid, was synthesized by von Gerhardt in 1853. The name aspirin was formed from contractions of the terms "acetyl" and Spirsäure, the latter referring to the genus Spiraea, one of the botanical sources from which salicylic acid was obtained.
Aspirin, generally available as powders, was introduced into medicinal practice in Germany before the turn of the century, and the tablet form was introduced into the United States in 1915. It has since become the most widely