Treatment of asthma as add-on therapy in patients with mild to moderate persistent asthma who are inadequately controlled on inhaled corticosteroids and in whom “ as-needed” short acting β -agonists provide inadequate clinical control of asthma; as an alternative treatment option to low-dose inhaled corticosteroids for patients with mild persistent asthma who do not have a recent history of serious asthma attacks that required oral corticosteroid use, and who have demonstrated that they are not capable of using inhaled corticosteroids; prophylaxis of asthma in paediatric patients in which the predominant component is exercise-induced bronchoconstriction.