The evidence for medication in exercise-induced asthma is limited to small randomized controlled trials (RCTs). Different study designs and dose and duration of medication make it difficult to draw definite conclusions. Overall, short-acting beta2-agonists appear to be the most cost-effective therapy for preventing symptoms of exercise-induced asthma. Very few head-to-head studies have been conducted, and no evidence is available for children younger than 5 years:
- Long-acting beta2-agonists (LABAs): in small RCTs, LABAs were more effective than placebo in controlling exercise-induced asthma, but no more effective than short-acting beta2-agonists. The benefit appears to decrease with long-term use [SIGN and BTS, 2011]:
- An RCT crossover trial (n = 24 children) showed formoterol to be similar to terbutaline in bronchodilator effect for exercise-induced asthma [Hermansen et al, 2006].
- An RCT (n = 20 adults) compared salmeterol (twice daily for 1 month) with placebo. All participants underwent 30 minutes of exercise after the morning dose and 9 hours later. The benefits appeared to be minimal at 9 hours, especially on days 14 and 29 [Nelson et al, 1998].
- Leukotriene receptor antagonists: most evidence is available for montelukast.
- When taken regularly, montelukast appears to be more effective than placebo and at least as effective as LABAs (especially over the longer term) in preventing exercise-induced asthma. Montelukast may provide some benefit in preventing bronchospasm by use of a single dose before exercise, but larger studies are needed to confirm this [Pearlman et al, 2006].
- Cromones (nedocromil and sodium cromoglicate):
- A systematic review (search date September 2001, 20 trials, n = 280) showed that nedocromil given before an exercise challenge test appears to be effective at preventing exercise-induced asthma, especially in people with more severe bronchoconstriction [Spooner et al, 2002].
- A systematic review (search date March 2000, eight RCTs, children > 6 years of age) showed no significant difference between sodium cromoglicate or nedocromil (at different doses) in preventing or reducing exercise-induced asthma symptoms for up to 2 hours [Kelly et al, 2000].