FDA is reviewing new data and reports on the safety of GlaxoSmithKline’s blockbuster diabetes drug Avandia, and will present findings at a public meeting this summer.

Discussions over the drug’s cardiovascular side effect were reignited last weekend after internal FDA reports expressing concern about Avandia surfaced in the New York Times, in addition to a report from Sens. Max Baucus (D-MT) and Chuck Grassley (R-IA) that examined internal GSK communications, FDA documents and other materials beginning in May 2007.

According to Baucus and Grassley’s report, GSK sought to suppress negative findings about Avandia’s side effects – from intimidating independent physicians to downplaying published studies – since 1999, the year Avandia was approved. The report also contains statements made by two FDA officials – David Graham and Kate Gelperin – that rosiglitazone, the active ingredient in Avandia, should be “removed from the market.” GSK issued a statement rejecting the Senate findings.

Sales of Avandia have steadily decreased over the last few years, while sales of Takeda’s Actos have increased, based on fewer heart-related side effects. According to IMS Health data, Avandia prescriptions for the year ending in July 2009 were down 28% to 1.6 million. During the same period, Actos had over 8 million scripts filled, earning $1.7 billion. Avandia will begin losing some patent protection in 2012. According to FDA’s Orange Book, Actos will hold a majority of its patents until 2016.

Advertising materials for Takeda’s Actos (pioglitazone) have targeted Avandia’s safety risks in the past. In November 2007, just days after Avandia picked up a second black box warning, Actos launched a print campaign touting the drug’s ability to ”lower blood sugar without increasing your risk of having a heart attack or stroke.” Calls to Takeda about any new advertising materials were not immediately returned.