Ciclesonide is an inhaled corticosteroid (delivered via a hydrofluoroalkane metered-dose inhaler) that is converted to an active metabolite, desisobutyryl-ciclesonide, in the lung, thereby minimising effects on endogenous cortisol. In two 12-week, randomised studies in patients with asthma, ciclesonide 80 or 320 microg once daily was at least as effective as budesonide 400 microg/day at increasing forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) from baseline; ciclesonide 320 microg daily was significantly more effective than budesonide 400 microg once daily in one study. In a randomised, double-blind study in patients with asthma controlled with high-dosages of inhaled corticosteroids, FEV(1) and FVC decreased significantly from baseline at 12 weeks in patients receiving ciclesonide 320 microg daily or budesonide 400 microg daily; peak expiratory flow values decreased significantly only in patients receiving budesonide. Inhaled ciclesonide 80 or 320 microg daily improved asthma symptom scores and decreased the use of rescue medication by a similar, significant amount to budesonide 400 microg/day in two 12-week studies. Inhaled ciclesonide was generally well tolerated in patients with asthma. Ciclesonide did not suppress biochemical markers of adrenal function in 52-week studies. The long-term (>52 weeks) systemic effects of ciclesonide remain unknown.