The Loss of Smell in Persistent Allergic Rhinitis Is Improved by Levocetirizine due to Reduction of Nasal Inflammation but Not Nasal Congestion (the CIRANO Study)

Background: Persistent allergic rhinitis (PER) has a moderate impact on the sense of smell, but no controlled study has reported the effect of antihistamines on the loss of smell in patients with PER. Methods: Patients with PER and subjective loss of the sense of smell (n = 27) were included in this pilot randomised, double-blind, placebo-controlled study. Nasal symptoms, nasal endoscopy, skin prick test, acoustic rhinometry, peak nasal inspiratory flow, nasal nitric oxide (nNO), and olfactometry (Barcelona Smell Test-24; BAST-24) were performed and evaluated in all PER patients at baseline and after 7 and 30 days of treatment with levocetirizine 5 mg or placebo. Results: The study population was randomized into two homogeneous groups: levocetirizine (n = 14) and placebo groups (n = 13). The evolution of symptoms reflected the therapeutic effect of levocetirizine treatment on rhinorrhea, nasal itching, eye itching, sneezing, and the total symptoms score after 7 and 30 days. Significant improvement in loss of smell by a visual analog scale (VAS) was observed after 7 days of levocetirizine treatment (7.2 +/- 4.3; p < 0.05) compared to placebo (-9.4 +/- 6.2). Improvement in smell identification by BAST-24 was strongly correlated (r = 0.72; p < 0.05) with smell improvement by VAS after 30 days. After 7 days of treatment with levocetirizine, the nNO values decreased (-494 +/- 188) compared to placebo (155 +/- 284 ppb; p < 0.05). Conclusions: The CIRANO study suggests that levocetirizine is effective on PER symptoms, including a transient improvement in loss of smell, and that this improvement concurs more with reduction of nasal inflammation than of nasal patency. Copyright (C) 2012 S. Karger AG, Basel