Background: Levocetirizine is chemically know as (R)-(-)-2-[4-(4-chlorobenzhydryl)-1-
piperazinyl]-ethoxy acetic acid dihydrochloride. Many publications have reported the synthetic routes
of levocetirizine. Several related substances have been detected in levocetirizine hydrochloride drug
substances. In our study, a pharmaceutical impurity, at the level of >0.1% w/w, was isolated, purified
and identified. It is not included in the European Pharmacopoeia (EP).
Objective: Identification, isolation and characterization of a new pharmaceutical impurity in levocetirizine
Methods: The impurity was enriched by normal phase silica gel, and was further purified by semipreparative
HPLC. It was separated from the crystallization mother liquor of levocetirizine hydrochloride
for the first time. Mass spectrometry and nuclear magnetic resonance spectroscopy are the ultimate
tools in structure elucidation.
Results: The structure was identified as levocetirizine quaternary ammonium. The formation mechanisms
of the impurity are also presented. The method was applied to the determination of the impurity
in levocetirizine hydrochloride in real samples.
Conclusion: The method was applied to the determination the impurity of levocetirizine hydrochloride
in real samples.