Displaying 7 results of Cetirizine Stable Isotopes Cetirizine is an antihistamine medication used to treat allergy symptoms such as itching, runny nose, and sneezing. Cetirizine stable isotopes are isotopically labeled forms of cetirizine used in pharmacokinetic studies to trace the drug's behavior in the body. These isotopes have identical chemical and biological properties to the non-labeled drug, but can be easily tracked and quantified in biological samples.