Nandrolone (INN, BAN), also known as 19-nortestosterone or 19-norandrostenolone, is a semisynthetic anabolic-androgenic steroid (AAS) derived from testosterone. The drug itself is inactive orally due to its lack of a 17α-alkyl group (which renders it vulnerable to extensive first-pass metabolism) and is not actually employed in medicine. Instead, nandrolone is used in the form of a variety of long-acting prodrug esters (see nandrolone ester) for intramuscular injection, the most common of which are nandrolone decanoate (Deca-Durabolin, Eubolin, Retabolil) and, to a lesser extent, nandrolone phenylpropionate (Durabolin, Fenobolin).