Why fexofenadine is considered as a truly non-sedating antihistamine with no brain penetration: a systematic review.

Objective: Fexofenadine is a second-generation inverse agonist of H₁-receptor of histamine which is highly selective with proven efficacy in relieving symptoms associated with allergic conditions. It has an additional benefit of not penetrating the blood-brain barrier and therefore do not induce sedation and not impair the cognitive function/psychomotor performance. This review aimed at providing evidence based on available controlled studies to reinforce the non-sedative property of fexofenadine for treating patients with allergic rhinitis and urticaria.

Methods: We performed an electronic literature search using keywords such as fexofenadine, drowsiness, somnolence, sedation, fatigue, cognitive, impairment, psychomotor, driving performances, sleep, rapid eye movement, alertness, clinical study, in vitro study, in vivo study, and pharmacodynamics in the Embase search engine. The review included randomized controlled trials, review articles, systematic reviews, and meta-analyses, together with post-marketing analysis conducted in healthy subjects and patients with allergy and were focused on comparing the antihistaminic potential or safety of fexofenadine with other antihistamines or placebo.

Results: Positron emission tomography (PET) and proportional impairment ratio (PIR) data along with other objective tests from various studies confirmed the non-sedative property of fexofenadine. Results of brain H₁-receptor occupancy (H₁RO) obtained from PET showed no H₁RO by fexofenadine, the receptor which is known to cause sedation of H₁ antihistamines. Most studies calculating PIR value as 0 showed fexofenadine to be a non-impairing oral antihistamine regardless of dose. Clinical trials in adults and children showed fexofenadine to be well tolerated without sedative effect or impairment of cognitive/psychomotor function even at higher than recommended doses.

Conclusion: Published literature based on various parameters and clinical trials conducted for evaluating the effect of fexofenadine on sedation and central nervous system shows fexofenadine is both clinically effective and non-sedating.