Objective and Subjective Bronchodilation over 12 Hours After Inhaled Formoterol: Individual Responses

Abstract

The aim of the present study was to compare the duration of bronchodilation obtained with 12 μg formoterol and 24 μg formoterol with that of 200 μg salbutamol over 12 hr. Thirteen stable asthmatics (mean age 59 years, asthma duration 7 years, mean FEV₁ 56% predicted, and reversibility to β-adreno-ceptor stimulation 36%) were studied in a double-blind crossover study. Lung function test (FENA₁ and FVC), heart rate, tremor, and subjective effects were recorded before and 30 min after the test doses and every hour up to 12 hr. The test doses were randomized and given double-blindly as two puffs using a spacer. The median duration of effect, defined as time when FENA₁ fell below 20% the maximum bron-chodilating capacity, was longer than 12 hr for both formoterol doses, whereas it was 7 hr for salbutamol (p < 0.01). No difference between the two doses of formoterol was seen. The median of the patients' subjective evaluation of the duration of effect was 12 hr, more than 12 hr for 12 and 24 μg formoterol, respectively, and 8 hr for salbutamol (p < 0.01). Only 1 patient needed rescue medication on the 2 formoterol days. However, 6 patients inhaled rescue medication during treatment with salbutamol. There were no differences with regard to heart rate, blood pressure, subjective tremor, or palpitations.

Formoterol, 12 μg and 24 μg, was shown to produce at least 12 hr of bronchodilating effect in most patients. However, there was considerable individual variation in duration of effect.