Inhaled beta 2-adrenoceptor agonists in asthma: help or hindrance?

Conventional low doses of inhaled beta 2-adrenoceptor agonists produce effective bronchodilation without systemic effects. Higher doses of inhaled beta 2-adrenoceptor agonists may produce substantial improvements in bronchodilator response, which may be helpful to patients with more severe airway obstruction. At higher than recommended doses, in asthmatic patients, fenoterol appears to cause greater dose-related systemic beta 2-responses compared with salbutamol or terbutaline, although there is no evidence to suggest that fenoterol is any less beta 2-selective in vivo. Furthermore, tolerance develops to systemic but not to bronchodilator effects during chronic treatment with inhaled beta 2-adrenoceptor agonists. The link between asthma mortality and systemic adverse effects of inhaled beta 2-adrenoceptor agonists at present remains unproven. A critical reappraisal of the regular use of inhaled beta 2-adrenoceptor agonists including long-acting drugs is now indicated in the light of their possible adverse effects on disease control. Patients requiring regular use of inhaled beta 2-adrenoceptor agonists should be given additional anti-inflammatory therapy with inhaled corticosteroids.