Ameredes Bill T, Calhoun William J
Department of Internal Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1083, USA.
Front Biosci (Elite Ed). 2010 Jun 1;2(3):1081-92. doi: 10.2741/e166.
Albuterol has been used in the acute treatment of asthma exacerbations for over 25 years. Its cost is low, and delivery can be tailored to allow dose-effect titration. Like other beta-2-adrenergic receptor agonists, it can exist as a racemate of two enantiomers, one active ((R)-albuterol), and one traditionally considered inert ((S)-albuterol). Basic investigations in airway cells and models from animals and humans have shown that (R)-albuterol, in both racemic and single enantiomer formulations, produces changes consistent with both relaxation of airway smooth muscle cells, and the reduction of inflammation. In contrast, (S)-albuterol typically has produces effects opposite to those of (R)-albuterol, i.e., antagonistic to the beneficial desired effects. Coupled with the fact that (S)-albuterol can persist 12 times longer than (R)-albuterol within the human circulation, findings suggest that paradoxical effects, sometimes seen with chronic racemic albuterol use, are due to (S)-albuterol. A number of clinical studies, to date, have been generally consistent with these findings; however, overwhelming evidence for clinical superiority of the (R)-albuterol single enantiomer over that within racemic albuterol remains to be obtained.
