Real Life Pharmacology - Pharmacology Education For Health Care Professionals

On this episode of the Real Life Pharmacology Podcast, I discuss cetirizine pharmacology. Cetirizine, commonly known as Zyrtec, is a 2nd generation antihistamine. Compared to 1st generation antihistamines, like diphenhydramine and chlorpheniramine, 2nd generation antihistamines have fewer anticholinergic effects. Pharmacologically, cetirizine works by selectively blocking histamine from binding to the H1 receptor. The uses for cetirizine are allergic rhinitis, itching, and sometimes acute allergic reactions. Commonly, cetirizine is dosed at 10 mg daily, and can even be escalated to 10 mg twice daily in rare situations. In adults 77 years old and older, the manufacturer recommended dose tops out at 5 mg daily. There are also liquid and chewable formulations for children.  The adverse drug reactions cetirizine are mostly dose-dependent and related to its pharmacology. Out of all of the 2nd generation antihistamines, like fexofenadine and loratadine, cetirizine is the most sedating. Other adverse drug rea