Cetirizine Impurity B dihydrochloride

Cetirizine Impurity B dihydrochloride is a synthetically derived byproduct arising from the alkylation step in cetirizine production, characterized by a substituted piperazine core linked to a chlorinated cyclopropylmethyl group and a phenethyl moiety. The compound exhibits three chlorine atoms, including two from the dihydrochloride salt, and retains the essential aromatic ring substitution pattern of the parent drug. Its structural divergence stems from an additional chlorination event at the cyclopropylmethyl side chain. This impurity serves as a critical HPLC reference standard for quantitative analysis of cetirizine raw material purity.