Time course of response to oral and inhaled corticosteroids in non-asthmatic chronic airflow obstruction.

One hundred and twenty one patients considered on clinical grounds to have non-asthmatic chronic airflow obstruction completed a double blind, crossover trial comparing oral prednisolone 40 mg per day with inhaled beclomethasone dipropionate 500 micrograms thrice daily, each given for 14 days, with a 14 day washout period between treatments. The time course of response was analysed for the 57 occasions where there was a significant increase in mean daily peak expiratory flow (PEF) over the treatment period. Mean daily PEF was still rising at day 14 on 12 occasions. After withdrawal of treatment mean daily PEF remained above pretreatments levels for more than two weeks in half the responses analysed. The peak response occurred earlier with inhaled beclomethasone (median 9.5 (range 3-14) days) than with oral prednisolone (median 12 (range 1-14) days), though both treatments produced a response that was sustained for a similar period. The results suggest that a trial of treatment with corticosteroids in this group of patients should last more than 14 days, and that in a study with a crossover design the washout period should be longer than two weeks.