Study of the Effect of Vitamin D as an Add-on Therapy to Corticosteroids in Asthma

Inclusion Criteria

• •Men and women 18 years of age and older
• •Physician-diagnosed asthma for at least previous 12 months
• •Asthma confirmed by: (a) β-agonist reversibility of forced expiratory volume in 1 second (FEV1) ≥12 % following 180 mcg (4 puffs) levalbuterol at visit 1 OR (b) methacholine provocative concentration causing a 20% fall in FEV1 (PC20) ≤ 8 mg/ml if not receiving an inhaled corticosteroid or ≤ 16 mg/ml if receiving an inhaled corticosteroid at visit 2. Source documentation for PC20 from an AsthmaNet methacholine challenge completed within 6 months of visit 2 will be accepted.
• •Stable asthma controller therapy (inhaled corticosteroid or leukotriene modifier only) dose for past 2 weeks
• •FEV1 ≥ 50% of predicted at visit 1
• •Vitamin D level of less than 30 ng/ml at visit 0
• •Experienced no more than one treatment failure in the VIDA run-in or oral corticosteroid (OCS) response periods on previous enrollments
• •For women of childbearing potential: not pregnant, non-lactating, and agree to practice an adequate birth control method for the duration of the study