This is a prospective study of montelukast efficacy in addition to standard treatment of status asthmaticus in children who are in the PICU. The study will be stratified in 2 groups: children 6-12 years of age and adolescents 13-18 years of age. Children who meet eligibility requirements will be randomized to receive a rapid-dissolving oral dose of montelukast or placebo. Participants will be given a physical exam, have FEV1 measurements and clinical asthma scores recorded pre- and post- completion of a nebulized albuterol treatment of 0.1 mg/kg/dose (min 2.5 mg/dose). Blood samples for PK analysis will be collected prior to study drug administration and at predetermined time intervals to determine the plasma level of montelukast. In addition, a blood sample will be obtained for genetic study of polymorphisms of CYP3A4, CYP3A5, and CYP2C9.