A drug used in inhalers to treat asthma could actually counteract the intended benefits of the therapy, researchers at the University of Pittsburgh School of Medicine reported, which could explain why some asthma patients' conditions worsen over time. The potentially harmful ingredient is albuterol, which has two forms or isomers — a so-called right-handed version and a left-handed one. The "right" version relaxes airways when used with the steroid dexamethasone, but the "left" version increases the inflammatory signals that caused the airways to tighten. One potential explanation for the harm to patients is that long-term repeated usage of albuterol may result in accumulation of the (left) isomer of albuterol, which persists in the body three to four times longer than the beneficial (right) isomer, normally metabolized in roughly three hours. It is now possible to make a version of albuterol that contains only the beneficial, right-handed isomer, and the study recommends companies examine this possibility.


SOURCE: FDA