OBJECTIVES DuoResp^® Spiromax^® (budesonide + formoterol fumarate dihydrate) is a fixed-dose combination (FDC) of inhaled corticosteroid (ICS) + long-acting beta agonist (LABA) in a novel dry powder inhaler (DPI).  An economic model was developed to assess the budget impact of using DuoResp^® Spiromax^® instead of Symbicort^® Turbohaler^® – a DPI delivering the same FDC – to manage adult patients with persistent asthma and chronic obstructive pulmonary disease (COPD) in the United Kingdom (UK).  The potential cost benefit of improved inhalation technique, due to the innovative characteristics of the Spiromax^® inhaler, was also investigated.  METHODS The eligible adult patient population was based on current confirmed UK asthma and COPD diagnosis rates, with the proportion of patients receiving FDCs based on market research data.  The costs of Symbicort^® Turbohaler^® and scheduled and unscheduled healthcare events were taken from publically available UK sources.  Frequency of poor inhalation technique with Symbicort^® Turbohaler^® and the associated increased risk of unscheduled healthcare events were taken from a large (n=1,664) cross-sectional, Italian observational study.  The estimated reduction in the proportion of patients with poor inhalation technique with DuoResp^® Spiromax^® compared with Symbicort^® Turbohaler^® was based on a conservative assumption. RESULTS An estimated 409,445 adult patients used Symbicort^® Turbohaler^® annually in the UK and were therefore eligible for treatment with DuoResp^® Spiromax^®, with 178,108 of these exhibiting poor inhalation technique.  Assuming a hypothetical uptake of DuoResp^® Spiromax^® reaching 25% in year 4 and 5 and its anticipated price, the model predicted drug cost savings totalling £36.09 million.  Furthermore, 39,266 unscheduled healthcare events could be avoided due to the predicted improvement in inhalation technique with DuoResp^® Spiromax^® compared with Symbicort^® Turbohaler^®, resulting in further savings of £3.50 million.  CONCLUSIONS DuoResp^® Spiromax^® is likely to offer budgetary savings compared with Symbicort^® Turbohaler^®, with further cost savings potentially resulting from improved inhalation technique.