ANALYSTS: ADVAIR'S GROWTH COULD BE IMPEDED BY FDA LABELING PROPOSAL

Future growth opportunity for GlaxoSmithKline's (GSK) best-selling asthma treatment Advair could be curtailed if the firm places restrictions on the drug's use, as was recently recommended by federal regulators, say financial analysts.

The FDA put Advair (fluticasone propionate/salmeterol xinafoate) on shaky ground late last week when it recommended that GSK update its existing product labeling with new warnings and a medication guide to alert healthcare professionals and patients that the drug may increase the chance of severe asthma episodes.

Advair was one of three long-acting beta 2-adrenergic agonists (LABAs), a class of bronchodilators, singled out by the FDA, which warned that although LABAs are intended to reduce the frequency of asthma attacks, clinical data has shown that the drugs may make asthma episodes more severe when they occur. The other products named in the public health advisory were GSK's Serevent (salmeterol xinafoate inhalation powder) and Novartis' Foradil (formoterol fumarate inhalation powder).

Current product labeling for LABAs include warnings alerting patients that postmarketing trials showed the drugs might cause asthma exacerbations in some patients, but the FDA has asked for a stricter warning stating that Advair, Serevent and Foradil should not be first-line treatments for asthma.

Wall Street analysts said such a warning would limit the drugs' potential growth. "In our opinion, Advair's restriction to second line asthma is potentially a greater concern, as it could reduce the potential future growth opportunity for Advair by limiting penetration into early/mild asthmatics," Merrill Lynch analyst Graham Parry wrote in a recent research note.

Current Advair sales would probably not be affected by the proposed labeling revision, said Parry, who noted that a large proportion of Advair sales are likely in the second-line setting anyway, and patients who are well-controlled on Advair are unlikely to be switched onto other medications. However, he noted that the labeling recommendation is a concern, "particularly given [Advair] is one of the company's key growth drivers."

GSK said recently that it intends to "work with the FDA to address the differences of opinion about how best to communicate the benefit-risk profile of these medicines for optimal patient care." The FDA must negotiate labeling revisions with drug manufacturers because it doesn't have the authority to force firms to alter their product labels.