How Much Cetirizine Can Be Used?

Discussion Antihistamine medications have been available for over 70 years. The original H1-antihistamines, while effective in treated allergic rhinitis, urticaria and other allergic problems, easily penetrated the blood-brain barrier and caused somnolence. The newer, second generation H1-antihistamines have much less somnolent side effects because of poor penetrance. Fexofenadine (Allegra®), desloratadine (Claritin®) and levocetirizine (Zyrtec®) are commonly used H1-antihistamines in the US today. Previously Astemazole (Hismanal®) and Terfanadine (Seldane®) were used but were withdrawn because of problems with cardiac arrhythmias with a propensity to prolong the QT interval. Fexofenadine in studies has the same somnolence producing effect as placebo. Desloratadine and cetirizine both can have some sedative effects. Cetirizine is extensively and rapidly absorbed by the gut allowing a rapid onset of action. It interacts with target receptors at effective concentrations, and organs where it would not be effective or toxic are avoided. There is no hepatic metabolism (thus avoiding many potential drug-drug interactions) and the drug is excreted unchanged by the kidney. The half-life is about 10.5 hours in adults. Cetirizine has higher binding affinity for receptors than other similar drugs thus it has “…a more potent, faster onset and longer duration of action…” when used for seasonal allergic rhinitis. “…[T]here is eviden...
Source: PediatricEducation.org - Category: Pediatrics Authors: Tags: Uncategorized Source Type: news