Doultegravir Imp D(Ring open Impurity)

Dolutegravir Impurity D is a ring-opened degradation product formed via hydrolytic cleavage of the lactam ring in the pyridone core of the parent drug. This impurity retains the sulfonamide functionality but exhibits a linearized structure due to the loss of the cyclic amide moiety. The open-ring configuration introduces a terminal carboxylic acid group, altering the molecule's polarity and hydrogen-bonding capacity. This impurity arises during synthetic processing or storage under acidic conditions and serves as a critical HPLC reference standard for quantifying process-related degradation in Dolutegravir formulations.