This review assesses the evidence regarding the use of long-acting  2 -agonists in the management of pediatric asthma. Thirty double-blind, randomized, controlled trials on the effects of formoterol and salmeterol on lung function in asthmatic children were identified.
Single doses of inhaled salmeterol or formoterol cause prolonged bronchodilatation (>12 h) and extended bronchoprotection against exercise-induced bronchoconstriction in children, some children achieving full protection for more than 12 h. Heterogeneity in bronchoprotection has been observed, and individual dose-titration may be attempted. The onset of action of formoterol is comparable to salbutamol, while salmeterol has a slower onset of action. Partial tolerance develops when long-acting  2 -agonists are used as regular treatment, including cross-tolerance to short-acting  2 -agonists. Regular treatment with salmeterol in children with or without corticosteroids provides statistically significant bronchodilatation, but the degree of improvement in lung function or bronchoprotection against exercise and nonspecific irritants is small with regular use. There is no evidence of anti-inflammatory effects from inhaled long-acting  2 -agonists, which is reflected by unchanged or increased bronchial hyperreactivity and no reduction of exacerbation rates. The evidence does not support a recommendation for long-acting  2agonists as monotherapy, nor does it support their general use as regular add-on therapy.
In conclusion, long-acting  2 -agonists provide effective bronchodilatation and bronchoprotection when used as intermittent, single-dose treatment of asthma in children, but not when used as regular treatment. Future studies should examine the positioning of long-acting  2 -agonists as an "as needed" rescue medication instead of short-acting  2 -agonists for pediatric asthma management.