Focus on Inhaled β₂‐Agonists: Efficacy, Safety, and Patient Preference

Abstract

Inhaled β2‐agonists are a standard therapy for patients with obstructive lung diseases. Clinical efficacy, safety, and patient preference are important reasons that these agents have become so widely used. In addition to significant bronchodilatory effects, β2‐agonists have potentially clinically important effects on the lungs including promotion of mucociliary clearance and effects on inflammation. Albuterol, levalbuterol, and salmeterol are the most frequently used agents in the United States. In the acute care setting, short‐acting β2‐agonists are standard therapy for obstructive lung disease whereas the use of long‐acting β2‐agonists in this setting is less clear. Potential clinical issues regarding the use of β2‐agonists in the acute care setting include type of inhalational delivery method used, such as metered‐dose inhaler versus nebulization, use of heliox instead of oxygen, safety issues, and selection of agent. The role of the more recently available β2‐agonists—levalbuterol (the R‐isomer of albuterol) and formoterol—are evolving. Levalbuterol may have clinical and economic advantages in the emergency department setting, however, additional research is necessary to validate this observation.

Present and Prospective Therapeutic Regimens for COPD

“…Albuterol is a racemic mixture of (R)-albuterol which produces a bronchodilator effect and (S)-albuterol which has no therapeutic effect, but may worsen airway inflammation and increase intracellular calcium levels promoting smooth muscle contraction and bronchial hyperresponsiveness. [23][24][25][26] It may also recruit and activate eosinophils in the airway. Levalbuterol is the single isomer of (R)-albuterol and some believe this gives it an advantage over albuterol.…”

“…1,9 Chronic administration of B2 agonists causes downregulation and decreased binding affinity to the B2 receptors. 26 As a result, patients develop tolerance to the effects of the drugs; however the lungs seem less affected than other tissues because of the large amount of B2 receptors found there. Tolerance usually develops the first week after initiation of chronic use and does not seem to worsen after this.…”