What is Nandrolone Undecanoate (Dynabolan) ? Nandrolone undecanoate (brand names Dynabolan, Dynabolon, Dynabolin, Psychobolan), or nandrolone undecylate, also known as 19-nortestosterone 17β-undecanoate, is a synthetic androgen and anabolic steroid and nandrolone ester. Dynabolon is a once popular anabolic steroid comprised of the active steroidal hormone Nandrolone attached to the very large Undecanoate ester. Very similar to Nandrolone Decanoate (Deca Durabolin), Dynabolon’s Undecanoate ester …