CinnarizineImpurity B

Cinnarizine Impurity B is a structurally related byproduct arising from the alkylation step in cinnarizine synthesis, characterized by a substituted ethyl group on the piperazine nitrogen and an extended methylene bridge connecting the phenothiazine core. Its molecular architecture retains the tricyclic phenothiazine scaffold but exhibits a modified side chain with reduced steric hindrance compared to the parent drug. This impurity serves as a critical HPLC reference standard for quantifying process-derived deviations in cinnarizine active pharmaceutical ingredient (API) batches.