Cefdinir (Unlabelled)

Cefdinir (Unlabelled) is a cephalosporin-derived API impurity characterized by a beta-lactam ring fused to a 1-azabicyclo[3.2.0]heptane core, substituted with an acetoxy group at C-3, a methylthio moiety at C-7, and a 2-amino-1,3-thiazole side chain. Its structure lacks the N-methyl substitution present in the parent drug, resulting from an incomplete methylation step during synthesis. This impurity exhibits a sulfhydryl group and a 4-carboxylic acid functionality, contributing to its distinct chromatographic behavior. It serves as an HPLC reference standard for quantifying process-related impurities in cefdinir drug substance analysis.