Aim: The replacement of chlorofluorocarbon (CFC) by hydrofluoroalkane has the potential to improve airway deposition of BDP. We investigated whether HFA-BDP extra-fine solution aerosol 400 μ g day⁻¹is as effective as CFC-BDP 1000 μ g day⁻¹in patients with stable, moderate asthma, having persistent bronchial hyper-responsiveness.

Patients and Methods: One hundred and fifty patients with moderate asthma from 20 centres, on inhaled steroids for ≤3 months, entered a 4-week run-in period with 1000 μ g day⁻¹CFC-BDP. Patients were then allocated to a 10-week study phase, receiving CFC-BDP 1000 μ g day⁻¹or HFA-BDP 400 μ g day⁻¹. Symptom score and PEF were measured daily and recorded as biweekly means. Spirometry, PC₂₀FEV₁, blood eosinophils and serum ECP were determined on days 15, 29, 43 and 71, and compared to the last visit of the run-in period. All group members were trained in a quality control centre.

Results: Treating the population of the HFA-BDP group (n=72) and the CFC-BDP group (n=78) did not show significant differences in terms of symptoms, lung function, airway hyperresponsiveness and serum markers of inflammation at the end of the run-in period and the end of the study phase.

Conclusion: Using HFA instead of a CFC metered dose inhaler, containing less than half the daily dose of BDP, allows control of symptoms and lung function parameters, without changes in bronchial hyperresponsiveness.