Montelukast, widely used in the treatment of asthma, is a selective and potent oral cysteinyl leukotriene-1 receptor antagonist. In this study, we investigated the effects of montelukast on oxidative stress and antioxidant defense in childhood asthma by measuring malondialdehyde and the paraoxonase activity. Twenty-five children with mild to moderate atopic asthma and 25 nonatopic children as controls were enrolled in the study. Asthmatic children were treated with montelukast, 5 mg tablets, for one month. Serum paraoxonase, malondialdehyde and high-density lipoprotein (HDL) cholesterol levels were measured before and after treatment. Serum paraoxonase and paraoxonase/HDL ratios were significantly increased after montelukast treatment. These parameters were significantly higher when compared with the normal subjects. Although montelukast treatment caused an enhancement in serum malondialdehyde, this increase did not reach statistical significance between the groups. The present study clearly demonstrates that montelukast increases paraoxonase activity in children with bronchial asthma. However, for better understanding of this enhancement, additional in vivo and in vitro studies are required.

Montelukast, widely used in the treatment of asthma, is a selective and potent oral cysteinyl leukotriene-1 receptor antagonist. In this study, we investigated the effects of montelukast on oxidative stress and antioxidant defense in childhood asthma by measuring malondialdehyde and the paraoxonase activity. Twenty-five children with mild to moderate atopic asthma and 25 nonatopic children as controls were enrolled in the study. Asthmatic children were treated with montelukast, 5 mg tablets, for one month. Serum paraoxonase, malondialdehyde and high-density lipoprotein (HDL) cholesterol levels were measured before and after treatment. Serum paraoxonase and paraoxonase/HDL ratios were significantly increased after montelukast treatment. These parameters were significantly higher when compared with the normal subjects. Although montelukast treatment caused an enhancement in serum malondialdehyde, this increase did not reach statistical significance between the groups. The present study clearly demonstrates that montelukast increases paraoxonase activity in children with bronchial asthma. However, for better understanding of this enhancement, additional in vivo and in vitro studies are required.