Rosiglitazone Versus Theophylline in Asthmatic Smokers

Smoking asthmatics have chronic pulmonary inflammation that is relatively steroid resistant. PPAR agonists (of which rosiglitazone is one example) have been shown to reduce several markers of inflammation in humans and in smoking animal models. This clinical study will use smoking asthmatics as a human model of smoke-induced steroid-insensitive airway inflammation to evaluate both efficacy of rosiglitazone as an anti-inflammatory drug as well as the effect of low doses of theophylline on the response to low-dose inhaled corticosteroid (LD ICS). Mild or moderate (as per GINA guidelines) persistent-asthmatic smokers will be randomised into this study after a 4-week washout period during which they will be withdrawn from inhaled corticosteroids (ICS). Subjects will then receive one of four treatments for 28 days: rosiglitazone, LD ICS, theophylline, or LD ICS plus theophylline. The effects of rosiglitazone and LD ICS on pulmonary function will be compared as a primary objective. In addition, effects of theophylline plus LD ICS will be compared against theophylline and LD ICS separately. Both pulmonary anti-inflammatory and systemic anti-inflammatory activity will also be investigated. Subjects will have baseline assessments of pulmonary function, biomarkers of systemic inflammation, sputum, exhaled breath biomarkers, asthma control questionnaires and safety parameters. Following 28 days of treatment, these parameters will all be reassessed in all subjects.