Aciclovir EP Impurity Q

Aciclovir EP Impurity Q is a structurally related degradation byproduct arising from oxidative hydroxylation at the purine ring's 9-position, introducing a hydroxyl group adjacent to the 6-amino functionality. This impurity retains the cyclopropane side chain of the parent drug but exhibits altered electronic properties due to the 9-hydroxyl substitution, which enhances polarity and reduces aromaticity. It serves as a critical HPLC reference standard for quantifying oxidative degradation pathways in aciclovir formulations.