Response of asthmatic patients to fenoterol inhalation: A method of quantifying the airway bronchodilator dose

Abstract

A radiotracer technique is described which enables direct measurement of the dose and distribution of inhaled aerosol bronchodilator in man. The mean (±SD) amounts of the B₂-adrenergic agonist, fenoterol, administered to a group of 12 asthmatic subjects in a double-blind randomized fashion were: placebo, 0 µg; low dose, 5.6 (± 1.2) µg; medium dose, 32.7 (±7.3) µg; and high dose, 127.5 (±29.2) µg, with a mean of 86.3% of the total subject dose being deposited in the lungs. The medium and high doses of fenoterol produced similar increases above baseline in forced expired volume in 1 sec (FEV₁), maximum flow at 50% of vital capacity (V_{max 50}), and maximum flow at 25% of vital capacity (V_{max 25}). These increases were greater than those with placebo for the entire 4-hr study (p < 0.01). The low dose of fenoterol was more effective than placebo in increasing FEV₁, V_{max 50}, and V_{max 25} above baseline values (p < 0.05), but not for the entire 4-hr study. The high-dose fenoterol caused palpitations and tremor in 3 of the 12 subjects, and the medium-dose fenoterol caused palpitations in one of these subjects.