Levothyroxine EP Impurity C

Levothyroxine EP Impurity C is a critical degradation byproduct arising from oxidative deamination of the parent thyronine scaffold. It retains three iodine substituents on the benzene rings but features a conjugated diketone system replacing the amino group at the lateral chain, introducing a carbonyl functionality at C-1 position. This structural modification disrupts the thyromimetic activity while maintaining chromophore integrity. The compound serves as a reference standard for HPLC method validation in levothyroxine potency assays.