Antihistamines in the treatment of allergic rhinitis

Abstract

Allergic rhinitis is a common allergic disease that have a substantially negative impact on the patients’ quality of life. Pharmacotherapy is essential to the treatment of allergic rhinitis, including the use of antihistamines, leukotriene receptor antagonists, topical steroids, decongestants, cromones, anticholinergics and their various combinations. Antihistamines are commonly prescribed drugs to treat mild, moderate, and severe disease. The article discusses the mechanisms of action of first- and second-generation antihistamines and compares the potential side effects and drug interactions.First-generation antihistamines differ in their significant sedative and hypnotic effect, mainly due to their pronounced lipophilic properties and ability to transverse the blood–brain barrier and bind to H1-histamine receptors in the central nervous system. Due to low selectivity of the first-generation antihistamines, they may interact with other receptors and develop adverse side effects, including dry mouth, nasopharynx, more rarely pupillary dilation, increased intraocular pressure, tachycardia, and urine retention. Bilastine is a highly selective second-generation antihistamine that has a rapid onset and a prolonged action. This drug does not interact with the P450 cytochrome system or undergo significant metabolism in the human body, and therefore the drug has low potential for drug-drug interactions. Bilastine is excreted almost completely unchanged and therefore does not require dose adjustment in patients with renal or hepatic impairment. Bilastine demonstrated similar efficacy in seasonal allergic rhinitis compared to cetirizine and desloratadine, as well as similar efficacy and safety in long-term treatment of patients with perennial rhinitis compared to cetirizine. Bilastine is well tolerated both at standard and at supratherapeutic doses, appears to have less sedative potential than other second-generation antihistamines, and has no cardiotoxicity.