Comparison between aerosol and powder delivery system of fenoterol plus ipratropium bromide ('Duovent') in patients with asthma and chronic bronchitis.

A study was carried out in 15 stable asthmatics and 5 patients with partially reversible airflow obstruction to compare the efficacy and tolerability of a single dose of 200 micrograms fenoterol plus 80 micrograms ipratropium bromide ('Duovent') administered either by metered dose aerosol or as a dry powder preparation for inhalation ('Inhalets'). Using a double-dummy technique, patients received each formulation, in random order, on 2 separate days within 1 week. Spirometric measurements were made over a period of 6 hours after the dose. The results showed that a 35% peak improvement in mean FEV1 occurred with each method of administration and there was no statistical difference between responses. Improvements of 25% were sustained for over 4 hours and effects on pulse rate and tremor were similar for both preparations.