Study Evaluations Throughout the study, starting with the baseline run-in period, patients will be required to daily record their PEFR and FEV1 (morning and evening), short-acting beta2-agonist use and clinical symptoms using a diary card. Mean weekly scores will be calculated for each parameter starting at week -1 up to week 12. Prior to administration of study drug at week 0 and, in addition, at weeks 1, 8 and 12, the following pharmacodynamic assessments will be made: breath NO levels, breath condensate leukotriene B4 & C4, pulmonary function testing (FEV1, FVC and PEFR), sputum induction for markers of inflammation (weeks 0, 1 and 8 only) and levels of markers of inflammation in peripheral blood. In addition, at weeks 2 and 6, breath NO levels will be measured and pulmonary function testing will be performed.