5-(4-Fluorophenyl)-1-(2-((2R,4R)-4-hydroxy-6-oxotetrahydro-2H-pyran-2-yl)ethyl)-3-isopropyl-2-oxo-N,4-diphenyl-2,3-dihydro-1H-pyrrole-3-carboxamide; 5-(4-Fluorophenyl)-2,3-dihydro-3-(1-methylethyl)-2-oxo-N,4-diphenyl-1-[2-tetrahydro-4-hydroxy-6-oxo-2H-pyran-2-yl]ethyl]-1H-pyrrole-3-carboxamide; 5-(4-Fluprophenyl)-1-{2-[(2R,4R)-4-hydroxy-6-oxotetrahydro-2H-pyran-2-yl]ethyl}-3-isopropyl-2-oxo-N,4-diphenyl-2,3-dihydro-1H-pyrrole-3-carboxamide; Atorvastatin Pyrrolidone Lactone; Atorvastatin Impurity 15; 1H-Pyrrole-3-carboxamide, 5-(4-fluorophenyl)-2,3-dihydro-3-(1-methylethyl)-2-oxo-N,4-diphenyl-1-[2-[(2R,4R)-tetrahydro-4-hydroxy-6-oxo-2H-pyran-2-yl]ethyl]-; 5-(4-Fluorophenyl)-2,3-dihydro-3-(1-methylethyl)-2-oxo-N,4-diphenyl-1-[2-[(2R,4R)-tetrahydro-4-hydroxy-6-oxo-2H-pyran-2-yl]ethyl]-1H-pyrrole-3-carboxamide