Nasal nitric oxide and nasal eosinophils decrease with levocetirizine in subjects with perennial allergic rhinitis

Allergic rhinitis is commonly treated with antihistamines. Monitoring improvement of airway inflammation noninvasively using nasal nitric oxide (nNO) would be clinically useful. To determine the anti-inflammatory effect of oral levocetirizine dihydrochloride (LC), we measured nNO and nasal eosinophils (nEos) in perennial allergic rhinitis (PAR) subjects.

A randomized double-blind placebo-controlled crossover design was used. Inclusion criteria consisted of subjects having a PAR history, exam and diary scores consistent with active symptoms, and positive skin testing. Subjects taking allergy medications 1 month before the study were not enrolled. After consenting, 31 subjects (24 female subjects; mean age, 29 years) were randomized to either oral LC (5 mg) or matching placebo for 2 weeks. After 2 week washout, subjects started the other 2-week treatment. At each visit, nNO was measured by aspiration at each nare using a nasal kit from NIOX (Aerocrine, Sweden) in parts per billion; nEos was collected from nasal smears and measured by microscopy using the scoring system (0-4+) and symptoms were self-reported using the allergic Rhinitis Quality of Life Questionnaire (RQLQ). Daily allergy symptom scores (total symptom score [TSS] 4) were collected at each visit.

During LC, mean baseline nNO was 807 ± 317 parts per billion (ppb; left) and 831 ± 332 ppb (right) and decreased significantly to 688 ± 266 ppb and 702 ± 286 ppb, respectively (p < 0.05). No significance was found during placebo treatment (778 ± 270 ppb, 808 ± 299 ppb to 802 ± 271 ppb, 813 ± 273 ppb). The mean nNO change was also significant compared with placebo (-125 ppb versus +14 ppb; p < 0.05). There was a significant decrease in nEos with LC compared with placebo (3.1-2.5 versus 2.9-2.6; p < 0.05). RQLQ scores were significantly improved with LC only. In TSS-4 scoring, a trend toward improvement during LC and significant worsening during placebo was found. Baseline nNO predicted changes in nasal eosinophils (nEos) and RQLQ.

We showed that oral LC therapy decreased objective markers of rhinitis inflammation, nNO and nEos, in patients with PAR. Improvement in symptom scoring was also found with LC treatment.