Abstract

Background:Asthma is a chronic inflammatory disease of airways in which many cells and
cellular elements play a role in particular, mast cells, eosinophils, T lymphocytes, macrophages,
neutrophils and epithelial cells. Inflammation causes recurrent series of wheezing,
breathlessness, chest tightness and coughing, particularly at night or in the early morning.
These episodes are usually associated with widespread and variable airflow obstruction that is
often reversible either spontaneously or with treatment.The inflammatory process can lead to an
associated increase in bronchial hyper- responsiveness (BHR) to a variety of stimuli (e.g.,
allergens, respiratory viruses and some occupational exposures). Reversibility of airflow
limitation may be incomplete in some asthmatic patients.Asthma is a heterogeneous disorder,
with different mechanism of disease processes. Many clusters of demographics, clinical and
pathophysiological characteristics are often called "asthma phenotypes"The
antibronchoconstrictor efficacy of antileukotriene drugs provided the main impetus behind their
introduction as the first novel class of asthma therapy in more than 20 yr. However, clinical
trials also provided surprising evidence for a hitherto unsuspected role of cysteinyl-leukotrienes
in promoting persistent eosinophilia in the airway and blood of patients with asthma, and
possibly influencing pathways involved in airway wall remodeling. A better under