Asthma treatment guidelines advocate the use of long-acting β2-agonists (LABA) in addition to inhaled corticosteroids (ICS) in patients whose asthma is uncontrolled by ICS alone, thereby addressing two processes fundamental to asthma: bronchoconstriction and inflammation. Superior control - including a reduction in severe exacerbations - of asthma and COPD by ICS/LABA combination therapy has been demonstrated. Results from clinical studies suggest additive and potentially synergistic effects when the two agents are used in combination. No new safety-related issues have been identified with ICS/LABA compared with the monocomponents.
The exact mechanisms for the enhanced efficacy of ICS/LABA combinations are under investigation but likely include drug interactions at the receptor level and interwoven signalling pathways, which may result in improved function of ®2- adrenoceptors and steroid receptors. Data from preclinical studies provide evidence of additive, compensatory, complementary and synergistic effects of ICS and LABA in the control of inflammation and airway and lung remodelling. These effects may contribute to the improved efficacy seen when treating asthma and COPD with ICS/LABA combinations in clinical studies.
Two ICS/LABA combination products are available: budesonide/formoterol (Symbicort®) and salmeterol/fluticasone propionate (SeretideTM). An ICS/LABA combination in a single inhaler represent safe, effective and convenient treatment options for the management of patients with asthma and COPD. Clinical results also suggest that adjustable dosing with budesonide/formoterol provides better asthma control than fixed dosing. Further elucidation of the underlying mechanisms responsible for this superior disease control is needed.