An important caveat for patients with mild asthma is that although the risk of a severe, life-threatening attack is low, it is not zero. All patients with asthma should be instructed in a simple action plan for severe, frightening attacks: to take up to four puffs of albuterol every 20 minutes over 1 hour. If no improvement is noted after the first four puffs, additional treatments should be taken while on the way to an emergency department or other higher level of care.
Inhaled muscarinic antagonists have so far earned a limited place in the treatment of asthma. The effects of short-acting agents (eg, ipratropium bromide) on baseline airway resistance are nearly as great as, but no greater than, those of the sympathomimetic drugs, so they are used largely as alternative therapies for patients intolerant of β-adrenoceptor agonists. The airway effects of antimuscarinic and sympathomimetic drugs given in full doses have been shown to be additive only in reducing hospitalization rates in patients with severe airflow obstruction who present for emergency care.
The long-acting antimuscarinic agents tiotropium and aclidinium have not yet earned a place in the treatment for asthma, although the addition of tiotropium to an ICS has been shown to be as effective as the addition of an LABA. As a treatment for COPD, these agents improve functional capacity, presumably through their action as bronchodilators, and reduce the frequency of exacerbations through currently unknown mechanisms.
If asthmatic symptoms occur frequently, or if significant airflow obstruction persists despite bronchodilator therapy, inhaled corticosteroids should be started. For patients with severe symptoms or severe airflow obstruction (eg, FEV1 < 50% of predicted), initial treatment with a high dose of an ICS in combination with an LABA is appropriate. Once clinical improvement is noted, usually after 4–6 weeks, the dose of treatment should be stepped down to no more than is necessary to control symptoms and maintain pulmonary function.
An issue for ICS treatment is patient adherence. Analysis of prescription renewals shows that only a minority of patients take corticosteroids regularly. This may be a function of a general “steroid phobia” fostered by emphasis in the lay press on the hazards of long-term oral corticosteroid therapy and by ignorance of the difference between glucocorticoids and anabolic steroids, taken to enhance muscle strength by now-infamous athletes. This fear of corticosteroid toxicity makes it hard to persuade patients whose symptoms have improved after starting treatment that they should continue it for protection against attacks. This context accounts for the interest in reports that instructing patients with mild but persistent asthma to take ICS therapy only when their symptoms worsen is nearly as effective in maintaining pulmonary function and preventing attacks as is taking the ICS twice each day.