The prevalence of asthma continues to increase. Despite the large number of available therapies, many patients continue to require emergency deparment (ED) visits and intensive therapy. However, ED visits continue to be a major contributor to the healthcare cost of asthma treatment. In the United States alone, asthma is the 11th most common reason for ED visits, with ED visits and hospitalizations accounting for almost 50% of the healthcare cost for asthma. Additionally, while only 20% of asthmatics have had ED visits or hospitalizations, these patients account for over 80% of the direct costs for asthma treatment. Current National Asthma Education and Prevention Program (NAEPP) guidelines regarding management of acute asthma exacerbations in the ED setting include: oxygenation for most patients, inhaled short-acting β2-agonists and systemic corticosteroids.

Zileuton, a specific 5-lipoxygenase inhibitor, has been extensively studied in inflammatory diseases such as asthma, which involve leukotrienes as mediators of inflammation. Zileuton Immediate Release (IR) tablets (Zyflo®) were approved by the Food and Drug Administration (FDA) in December 1996 for the prevention and treatment of asthma in adults and children 12 years of age and older. The results of the 2 pivotal studies in asthmatics with zileuton IR tablets demonstrated that zileuton at a dose of 600 mg QID produced and maintained a lasting improvement of lung function. In addition to the lasting effect of zileuton, an acute bronchodilation (as early as 60 minutes) was observed after administration of the first 600 mg oral dose.

This acute bronchodilator effect may benefit patients during an acute exacerbation of asthma when added to the usual care in the ED or clinic setting. Critical Therapeutics has developed an injectable formulation of zileuton that will be explored for use in acute asthma exacerbations. This initial study is intended to provide PK data, information on safety and tolerability and some indication of pharmacologic activity as evidenced by lung function changes. In an attempt to enhance the potential for observing effects on lung function, only those patients with a demonstrated ability to respond by an increase in FEV1 of at least 10% within 3 hours after oral zileuton dosing will be enrolled.