By Ben Hirschler and Lisa Richwine
LONDON/WASHINGTON (Reuters) - GlaxoSmithKline Plc's diabetes pill Avandia came under intense scrutiny on both sides of the Atlantic on Friday, leaving the drug's future uncertain as its maker battles a growing tide of lawsuits.
In London, the European Medicines Agency (EMA)launched a new review into the risks and benefits of the medicine, adding to pressure on a product that already faces a grilling from U.S. experts next week over its cardiovascular safety.
Ahead of the U.S. panel meeting on July 13-14, the Food and Drug Administration's (FDA) cardiology leader criticized a key Glaxo clinical trial on Avandia and said the true risk of heart attacks could be higher than the firm's study suggested.
Avandia was once Glaxo's second-biggest drug but its sales have plunged since safety fears first erupted three years ago. Revenues totaled 771 million pounds ($1.17 billion) in 2009, equivalent to 2.7 percent of Glaxo's group sales.
The big worry for investors, though, is litigation.
Concerns about the medicine's adverse impact on the heart have triggered a slew of lawsuits in the United States and fresh criticism of the drug from regulators is likely to make matters worse by playing into the hands of plaintiff lawyers.
Both the FDA and EMA will consider a range of options for Avandia, including whether the medicine should be pulled from the market over heart risks.
Experts from both agencies will pore over a mass of clinical studies that have various strengths and weaknesses and provide conflicting findings about the drug.
"There is not complete unanimity within the FDA about the interpretation of these data," Dr. Janet Woodcock, head of the FDA's drugs center, told reporters.
3-YEAR CONTROVERSY
Controversy has dogged the drug since 2007 when Cleveland Clinic researchers linked the pill to a higher heart-attack risk. An advisory panel that year agreed the data suggested Avandia may increase the chances of a heart attack for some patients but said the medicine should remain an option.
European regulators have also concluded in a number of previous reviews -- the last of which was early this year -- that the overall risk-to-benefit balance was favorable.
But that verdict may not last and the EMA said it would decide once all the relevant data was analyzed whether Avandia's marketing authorization should be revoked, suspended or changed.
Experts from the agency's Committee for Medicinal Products for Human Use (CHMP) will discuss the issue at their next plenary meeting in London on July 19-22.
Shares in British-based Glaxo were 1.2 percent lower at 11.28 pounds by 1345 GMT, after an earlier low of 11.16, underperforming a 0.5 percent gain in the European drugs sector.
Glaxo has vigorously defended its product and Tony Hoos, Glaxo's European medical director, said on Friday that Avandia was "an important treatment option for appropriate Type 2 diabetes patients."
Persuading doctors and patients of the benefits of a drug that was already slammed in a highly critical report from U.S. Senators in February is becoming an uphill battle, with two recent anti-Avandia studies adding to Glaxo's difficulties.
In one study, Dr. Steven Nissen, a cardiologist at Ohio's Cleveland Clinic and an outspoken Avandia critic, offered even more ammunition to his 2007 analysis that first suggested Avandia raises heart risks.
In the second, Dr. David Graham of the Food and Drug Administration and others found Avandia was more dangerous to the heart than Actos, a pill in the same class of drugs made by Japan's Takeda Pharmaceutical Co.
(Editing by David Cowell)
