Comparison of formoterol and terbutaline for as-needed treatment of asthma: a randomised trial

Background Asthma guidelines recommend that long-acting inhaled β-agonists should be used as maintenance therapy for patients with asthma inadequately controlled on an inhaled corticosteroid. We studied the safety and efficacy of the longacting β-agonist formoterol compared with terbutaline, each taken as needed, in patients with moderate to severe asthma. Methods Patients were taking an inhaled corticosteroid (mean dose 870 μg daily) and had a forced expiratory volume in 1 s (FEV1) of at least 50% predicted (mean 74%). Those requiring an inhaled β-agonist three to eight times a day during the study run-in period (362 of 621 who started) were randomly assigned formoterol 4·5 μg or terbutaline 0·5 mg as needed by Turbuhaler in daily doses up to 54 μg and 6 mg, respectively, for 12 weeks in a double-blind, parallel-group study. Analyses were by intention to treat. Findings The 362 randomised patients (157 men, 205 women) had a mean age of 47 years. Patients taking formoterol had a longer time to their first severe asthma exacerbation (relative-risk ratio 0·55 [95% CI 0·34–0·89]), took fewer inhalations of study drug, and had larger increases in FEV1 (5%) and morning and evening peak expiratory flow (mean difference in increase 11 L/min and 8 L/min) than those taking terbutaline. No safety issues were identified. Interpretation When taken as needed, formoterol 4·5 μg provided better asthma control than terbutaline 0·5 mg in patients requiring moderate doses of relief medication despite inhaled corticosteroid treatment. Safety studies should be extended to a wider population of patients with asthma.