2-Hydroxy-Atorvastatin calcium salt

2-Hydroxy-Atorvastatin calcium salt is a structurally modified derivative of Atorvastatin, featuring an additional hydroxyl group at the C2 position of the pyrrole ring. This compound retains the core scaffold of the parent drug, including the 2-(4-fluorophenyl)-3-methyl-4-phenyl-1H-pyrrole-5-yl moiety, but incorporates a calcium counterion and a hydroxyl substitution at the β-lactone ring's adjacent carbon. The hydroxylation introduces steric and electronic alterations, affecting metabolic stability and solubility. It arises as a degradation byproduct under oxidative stress conditions during Atorvastatin synthesis or storage. This compound serves as a critical HPLC reference standard for quantifying process-related impurities in atorvastatin calcium drug substance.