Onset of action of single doses of formoterol administered via turbuhaler in patients with stable COPD

We studied 16 patients with stable COPD in a double blind, double dummy, placebo-controlled, within patient study to see if formoterol could be used as a rescue drug. We compared the of onset of bronchodilation obtained with formoterol 12 mug (metered dose corresponding to 9 mug delivered dose) and formoterol 24 mug (metered dose corresponding to 18 mug delivered dose), both delivered via Turbuhaler, with that of salbutamol 400 mug and salbutamol 800 mug delivered via pressurized metered-dose inhaler (pMDI). Patients inhaled single doses of placebo, formoterol and salbutamol on five separate days. FEV1 was measured in baseline condition and 3, 6, 9, 12, 15, 18, 21, 24, 30, 40, 50, and 60 min after inhalation of each treatment. We examined two separate criteria for deciding if a response was greater than that expected by a random variation of the measurement: (1) a rise in FEV1 of at least 15% from the baseline value; (2) an absolute increase in FEV1 of at least 200 ml. Formoterol 12 mug (15.2 min; 95% CI 9.5-21.0) and formoterol 24 mug (15.1 min; 95% CI 8.9-21.2) caused a rise in FEV1 of at least 15% from the baseline value almost rapidly as salbutamol 400 mug (13.6 min; 95% CI 7.1-20.1) and salbutamol 800 mug (14.5 min; 95% CI 7.1-21.9). No significant difference (P = 0.982) in onset of action was seen between the four active treatments. According to Criterion 2, the mean time to 200 mi increase in FEV1 was 11.1 min (95'%, CI: 7.0-15.2) after salbutamol 400 mug, 13.0 min (95% CI: 7.9-18.1) after salbutamol 800 mug, 14.7 min (95% CI: 7.1-22.4) after formoterol 12 mug, and 12.7 min (95%, CI: 7.4-18.0) after formoterol 24 mug. Again, there was no significant difference (P = 0.817) between the four active treatments. Formoterol Turbuhaler 12 mug and 24 mug caused bronchodilation as rapidly as salbutamol 400 mug and 800 mug given via pMDI. (C) 2001 Academic Press.