FDA is requiring that type 2 diabetes drugs Avandia (rosiglitazone), from GlaxoSmithKline, and Actos (pioglitazone), from Takeda Pharmaceuticals, be labeled with a black box citing the risk of congestive heart failure (CHF).

The black-box warning issued for Avandia, however, is not related to the study in the New England Journal of Medicine that reported a 43 percent increased risk of heart attack among patients taking the drug. FDA is currently looking at a report issued by a panel of medical experts on the subject.

According to GSK, Avandia has included information about CHF in the prescribing information since the drug was approved by FDA in 1999 and has displayed a warning for "cardiac failure and other cardiac effects" since 2001.

"A black-box warning is never a good thing, but it's not a death sentence unto itself," said Richard Altus, CEO of ImpactRx. "Sometimes physicians already know that a risk exists, so the box is just the FDA catching up with what the physicians might already know through other studies." He notes that Celebrex was not hurt by the addition of a black-box warning, as physicians are still heavily prescribing it.

Altus continued, "Every time a black-box warning goes out, you have to look at the unique circumstance around that brand to really assess how it is going to adversely affect the brand and its market share."

GSK has already altered its consumer Web site for Avandia, noting the new warnings in bold letters and using half the main page to host safety information.