 During development and clinical trials the drug was called AMG531.Romiplostim is indicated as a potential treatment for chronic idiopathic (immune) thrombocytopenic purpura (ITP).Romiplostim was designated an orphan drug by the U.S. Food and Drug Administration (FDA) in 2003, as the chronic ITP population in the USA is under 200,000 (the chronic adult ITP population in the USA is thought to be around 60,000, with women outnumbering men by a factor of two).