U.S. group urges FDA to halt Glaxo's Avandia trial

* Public Citizen: Trial unethical, patients not informed

* Group asks FDA to act before July meeting

WASHINGTON, May 11 (Reuters) - An major trial of Avandia puts patients at risk and should be stopped, a U.S. advocacy group said on Tuesday in calling on regulators to halt the global study of the controversial GlaxoSmithKline Plc GSK.LGSK.N diabetes drug.

The U.S. Food and Drug Administration in 2007 asked the company to conduct the trial to compare the drug's long-term heart effects with those of rival Actos by Takeda Pharmaceutical Co Ltd 4502.T after other evidence suggested Avandia increased the risk of heart attack and chest pain.

But since then, even more data have linked Glaxo’s drug to greater heart risks, the science-based consumer advocacy group Public Citizen said. Continuing to enroll patients in the trial -- which aims to study 16,000 worldwide through 2015 -- unnecessarily puts people with diabetes at risk, it said.

The trial, known as TIDE, is “exposing thousands of high-risk patients with diabetes to a drug with an unfavorable safety profile and no clinical advantage over its comparator,” Public Citizen’s Health Research Group Director Sidney Wolfe and Canadian researcher David Juurlink wrote in a letter to FDA Commissioner Margaret Hamburg.

“A wealth of data now suggests” that Avandia carries greater risks than Actos, the researchers said. Patients are also not adequately informed about the safety differences between the two medicines when deciding whether to participate in the trial, they added.

FDA officials have said they are already taking a closer look at Avandia, also known as rosiglitazone, but have yet to draw any new conclusions about its use.

Glaxo has said it stands behind the safety and efficacy of Avandia when used appropriately.

The FDA’s outside advisory panel noted the drug’s heart risks at a 2007 meeting, but overwhelmingly recommended keeping it on the U.S. market even though an agency staff scientist urged its removal.

The FDA later called for a “black box” warning on Avandia’s label after a review of 42 studies associated the drug with an increased risk of heart problems compared with a placebo, although it called the overall data “inconclusive.”

Another FDA advisory panel is scheduled to meet publicly in July to review Avandia’s safety.

In its letter to the FDA, Public Citizen urged the agency to act before the summer meeting, adding that U.S. and European diabetes associations have already advised against the drug’s use.

According to the group’s letter, Glaxo’s TIDE trial involves 137 sites in 14 countries, including recently added locations in developing countries such as Latvia and Pakistan.

Glaxo has said that scientific evidence has not established an increased risk of heart problems and that it has openly provided data. Still, Avandia sales have dropped by more than half, from roughly $3 billion in 2006 to $1.2 billion in 2009.

Some U.S. lawmakers have also called for the FDA to pull Avandia from the market until the drug’s safety and effectiveness can be firmly established. (Reporting by Susan Heavey; Editing by Lisa Von Ahn)