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,
Aminohippuric acid was given along with penicillin in order to prolong the time penicillin circulated in the blood. Because both penicillin and "para"-aminohippurate compete for the same transporter in the kidney, administering "para"-aminohippurate with penicillin decreased the clearance of penicillin from the body by the kidney, providing better antibacterial therapy. Transporters found in the kidney eliminate organic anions and cations from the blood by moving substances, in this case, drug metabolites, from blood into urine. In vultures, the NSAID diclofenac, which is extraordinarily toxic to vultures, interferes with the renal transport of uric acid via the PAH channel. p"K" = 3.83 Aminohippuric