The aim of the study is to investigate the effect of ciclesonide versus fluticasone propionate versus placebo on airway hyperresponsiveness and on the hypothalamic-pituitary-adrenal axis (HPA axis). Treatment medication will be administered as follows: ciclesonide or fluticasone propionate will be inhaled twice daily, using one of the two dose levels. The study duration consists of a baseline period (4 to 6 weeks), five treatment periods (9 days each), and a washout period between treatments (4 to 12 weeks). The study will provide further data on safety and tolerability of ciclesonide.