Albuterol, in a class of medications called beta-agonists, is combined with steroids and is used to prevent and treat breathing problems caused by asthma and other lung diseases. It relaxes and opens the muscle surrounding air passages in the lungs, making it easier to breathe.
However, the study, presented by Williams Ameredes, Ph.D., research assistant professor of medicine and assistant professor of cell biology and physiology, in the division of pulmonary, allergy and critical care medicine at the University of Pittsburgh School of Medicine, may explain the paradoxical airway constriction and worsening of asthma in patients with continued use of beta-agonists.
"The research team of the Asthma, Allergy and Airway Research Center here at Pitt has had a long interest in mechanisms of beta-agonists, particularly due to the paradoxical responses to albuterol experienced by some asthmatics, that are severe enough to land them in the emergency department," Dr. Ameredes said.
"One potential explanation is that long-term repeated usage of albuterol may result in accumulation of the (S)- isomer of albuterol, which we know persists in the body 3-4 times longer than the beneficial (R)- isomer, which is normally metabolized in about three hours. Since the combination of steroid and beta-agonist therapy is prescribed for the long term for many asthmatics, we believed that it was reasonable to study the interaction of these compounds from the perspective of the isomers," he said.
Like other beta-agonists, chemically synthesized albuterol is typically called a "racemic" mixture. It is composed of 50 percent of the active version, or isomer, designated
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23-Mar-2004