Aciclovir EP Impurity B

Aciclovir EP Impurity B is a pyrimidine derivative featuring a fused imidazole ring, corresponding to the guanine core of the parent compound. This impurity arises from the cleavage of the acyclic cyclopropane moiety in Aciclovir, retaining the 9H-purine-6(9H)-one scaffold with exocyclic amino and oxo functionalities. It serves as a critical HPLC reference standard for quantifying degradation pathways in Aciclovir formulations.