Abstract
Nineteen patients with chronic airflow obstruction measured their morning and evening peak expiratory flow (PEF) daily for 28 days. A placebo was taken for the first week and prednisolone 20 mg twice daily was taken for the last three weeks. The mean PEF in 13 patients who responded to prednisolone reached a maximum after eight days' treatment. The majority of the 19 patients had asthma and were thought to represent a typical cross section of patients who would be considered for a trial of oral corticosteroids. Most responsive patients will achieve a maximum response within eight days.