Lenalidomide Impurity 1,5-Amino-4-(4-amino-1-oxoisoindolin-2-yl)-5-oxopentanoic acid,4-(4-Amino-1-oxoisoindolin-2-yl)-4-carbamoyl Butyric Acid is an open impurity of Lenalidomide, an immunomodulatory drug; analog of Thalidomide.,Lenalidomide Therapeutic