WASHINGTON, Nov. 21 (UPI) -- While shares of GlaxoSmithKline slipped 5 percent in the wake of new label warnings for the British firm's asthma drugs Advair Diskus and Serevent Diskus, an industry analyst predicted that the labeling update won't cause much of a ripple in sales of top seller Advair over the long term.
The Food and Drug Administration late last week requested that GSK and Schering -Plough add new labeling to their asthma drugs -- belonging to a drug class called beta agonists -- warning that the products may increase the risk of severe asthma episodes and death.
The update applies to GlaxoSmithKline's Advair Diskus and Serevent Diskus and Schering-Plough's Foradil Aerolizer.
But despite the new concerns, GSK shares are likely to bounce back in the next few months if it becomes clear that the new warning is not affecting Advair and Serevent's sales, Cynthia Mundy, a pharmaceutical analyst with Decision Resources, told United Press International.
"This is not a lightning bolt from the sky in terms of what physicians knew about the drug," she said. "This is not another Vioxx."
Mundy explained that both GSK drugs have carried black-box warnings for a couple of years, and despite the black box's status as the most serious of all drug label warnings, the change did not make much of a dent in sales of Advair.
She said Advair is the top-selling asthma drug in the United States, racking up more than $2 billion in annual sales.
So this latest regulatory wrinkle is likely to have little impact, she predicted. "Overall, physicians are comfortable prescribing Advair and feel it is safe and the most effective drug for treating asthma," Mundy said. Moreover, while the FDA is advising physicians to no longer use Advair as a first-line asthma treatment, prescribing of the drug as a second-line treatment -- for patients who can't control their condition with other therapies -- is likely to remain robust, she added.
Mundy noted that the latest revision to the asthma drugs' labeling is not based on new safety data, but instead stems from continued evaluation of the GSK-sponsored SMART study, which prompted the previous black-box label update.
Mundy said Advair has no close competitor in the U.S. market and that the drug also leads in Europe, with sales there approaching $1 billion. However, AstraZeneca's Symbicort is gaining on GSK's drug in the European market, racking up about $500 million in yearly sales, she said.
In issuing the new asthma warning, the FDA said that it had notified the companies "to update their existing product labels with new warnings and a Medication Guide for patients to alert health care professionals and patients that these medicines may increase the chance of severe asthma episodes, and death when those episodes occur."
The agency said it was concerned that Advair and the other long-acting beta2-adrenergic agonists decrease the frequency of asthma episodes, but also may make asthma episodes more severe when they occur.
A medication guide that cites these risks will be given to patients when they fill a prescription for one of these drugs, the FDA said.
