Mometasone furoate impurity C-III

Mometasone furoate impurity C-III is a low-molecular-weight degradation byproduct derived from the hydrolytic cleavage of the furoate ester moiety in the parent corticosteroid. It contains a furan ring fused to a dihydroxy-substituted pentanoic acid backbone, featuring two vicinal hydroxyl groups and a terminal carboxylic acid. This impurity arises via non-enzymatic hydrolysis under acidic conditions during API synthesis or storage. Structurally distinct from the parent drug’s glucocorticoid core, it serves as a critical HPLC reference standard for quantifying process-related impurities in mometasone furoate formulations.