Isolation and characterization of cetirizine degradation product: mechanism of cetirizine oxidation.

Purpose: The goal of the study was to isolate and analyze a cetirizine degradation product, formed within a PEG-containing formulation and to elucidate the mechanism of oxidation of cetirizine.

Methods: Cetirizine, formulated in PEG-containing matrix, was subjected to forced degradation conditions in the pH range from 3 to 10, and the product was analyzed by HPLC and LC-MS/MS. Additionally, pure cetirizine was subjected to selective oxidization by hydrogen peroxide and sodium percarbonate.