• Safety evaluation
  

• Pulmonary function tests.
  

The incidence of respiratory allergy in the US has increased gradually over the past several years, and current estimates suggest that allergic rhinitis and bronchial asthma affect approximately 20% and 5% of the population, respectively. Rhinitis and asthma frequently coexist, and large-scale population surveys indicate that up to 38% of subjects with rhinitis have asthma, and up to 78% of subjects with asthma have chronic nasal symptoms. Safety concerns with the increased use of inhaled corticosteroids, the heterogeneity of the disease, and poor compliance with asthma medication regimens, point to the need for the development of safe and convenient oral therapies for asthma. Oral leukotriene receptor antagonists (eg montelukast) are the latest class of inflammation-modulating asthma drugs and appear to cause fewer long-term side effects than systemic corticosteroids and reduce the need for shorter-acting bronchodilator reliever medicines. However variability in response between patients has been observed and clinical experience with these agents is still limited.

Histamine is an important chemical mediator of inflammation in asthma. The benefits of antihistamine treatment in patients with mild to moderate asthma have been well documented, however their clinical use has been previously limited due to the high doses required for efficacy and their associated side effects including sedation and cognitive impairment. Recent evidence indicates that in addition to H1-receptor antagonism, some of the newer nonsedating, non-impairing antihistamines appear to possess various anti-inflammatory properties at concentrations achieved at therapeutic dosages suggesting an additional benefit of these drugs in the management of allergic diseases and asthma. The purpose of this study is to assess the long-term safety performance of fexofenadine compared to montelukast in subjects with asthma.