The effect of montelukast sodium on serum arginase levels in patients with seasonal allergic rhinitis.

BACKGROUND: Nitric oxide (NO) imbalance appears to be important in the pathogenesis of allergic rhinitis. NO is synthesized from l-arginine by NO synthase (NOS). Competing with NOS for l-arginine is arginase, which catalyzes the hydrolysis of arginine to urea and ornithine. Therefore, increased serum arginase activity could potentially limit NO production catalyzed by inducible NOS, thus contributing to allergic rhinitis. This study was designed to investigate the effect of the cysteinyl leukotriene type 1 receptor antagonist, montelukast sodium on serum arginase levels in patients with seasonal allergic rhinitis. METHODS: Twenty-five patients with seasonal allergic rhinitis (SAR; treatment group) and 16 nonasthmatic patients without allergic rhinitis (control group) were included in the study. Serum arginase levels and the mean total nasal symptoms scores were measured before and after oral montelukast sodium (10 mg) was administered daily for 4 weeks to the treatment group. RESULTS: Serum arginase levels and the mean total nasal symptoms scores were significantly lower in the treatment group after montelukast sodium administration compared with the baseline levels (p = 0.001). Serum arginase levels were significantly lower in the treatment group compared with the control group (p = 0.01). There was no statistically significant difference between the serum arginase levels of the treatment group before treatment and the control group (p = 0.05). There was a weak correlation between the mean total nasal symptoms scores and serum arginase levels in the treatment group before montelukast sodium administration (rs = 0.40; p = 0.05). CONCLUSION: Montelukast sodium may reduce serum arginase levels and total nasal symptoms scores of patients with SAR. Additional studies that compare the effectiveness of nasal corticosteroid and montelukast sodium on serum arginase levels should be conducted.