阿托伐他汀内酰胺钙盐杂质

Atorvastatin Lactam Calcium Salt Impurity (CAS 1046118-41-5) is the calcium salt of the lactam analog of the HMG-CoA reductase inhibitor atorvastatin (free acid C33H35FN2O6, MW 574.64; calcium salt C66H68CaF2N4O12, MW 1187.3), in which the pyrrole ring of atorvastatin bears an additional carbonyl at C2 to give a 2-oxopyrrole (lactam) structure. This related substance is known as an oxidative/photodegradation product of atorvastatin. It is used as a reference standard for the identification and quantification of this impurity in atorvastatin and atorvastatin calcium APIs and finished formulations, supporting HPLC impurity profiling, method validation, and regulatory quality control.