Prodrug not its intended target. This reduces adverse or unintended effects of a drug, especially important in treatments like chemotherapy, which can have severe unintended and undesirable side effects. Many herbal extracts historically used in medicine contain glycosides (sugar derivatives) of the active agent, which are hydrolyzed in the intestines to release the active and more bioavailable aglycone. For example, salicin is a β-D-glucopyranoside that is cleaved by esterases to release salicylic acid. Aspirin, acetylsalicylic acid, first made by Felix Hoffmann at Bayer in 1897, is a synthetic prodrug of salicylic acid. However, in other cases, such as codeine and morphine,
Pyrophosphoric acid it is difficult to recrystallise from the melt. In aqueous solution pyrophosphoric acid like all polyphosphoric acids hydrolyses and eventually an equilibrium is established between phosphoric acid pyrophosphoric acid and polyphosphoric acids. When highly diluted, an aqueous solution of pyrophosphoric acid contains only phosphoric acid. Pyrophosphoric acid is a medium strong inorganic acid. Anions, salts, and esters of pyrophosphoric acid are called pyrophosphates. While pyrophosporic acid is corrosive, it is not known to be otherwise toxic. The name pyrophosphoric acid was given by a "Mr. Clarke of Glasgow" in 1827 who is credited with its discovery following the heating to