Despite concerns that use of long-acting β‐agonists (LABA) could be associated with risk of worsening asthma, to date these drugs have proven safe and highly effective 1,2.Early studies demonstrated no increase in asthma exacerbations when added to inhaled corticosteroids (ICS) aslong-term maintenance medication and subsequent studies have shown significantly reduced risks of exacerbations andimproved, more rapid establishment of asthma control compared to adding more ICS 3–5. Formoterol is a potent LABA with a rapid onset of bronchodilatation 6, 7 and a relatively fast clinical response when added as regular medication for patients whoare symptomatic on ICS alone 5, 8, 9. The question therefore arises, could formoterol with its rapid onset of action, also be used safely and effectively as reliever medication for asthma 10? Are there risks of tolerance associated with regular use of formoterol that could reduce its benefit when used as a reliever for acute symptoms 11?Are there other risks, associated with its adrenergic andmetabolic effects, that could be increased by its use whenadded to regular formoterol, resulting in worse outcomes 12?
Some of these questions have already been addressed in two12 week randomised controlled trials. Tattersfield etal.13 showed in a double-blind study in 362 symptomatic patients taking ICS (mean daily dose 870 µg) that formoterol 4.5 µg as reliever medication was associated with fewer asthma exacerbations and a longer time to first exacerbation compared to terbutaline 500 µg. Serum potassium and electrocardiogram variables were monitored at clinic visits and nodifferences between treatments were shown. The relative risk ratio for an exacerbation requiring oral corticosteroids was 0.55 (95% confidence interval 0.34–0.89). The average daily dose of formoterol was four puffs of 4.5 µg, and this didnot change over the period of the study. In a double-blind randomised controlled …