WASHINGTON - GlaxoSmithKline's drug Avandia should stay on the market, federal health experts voted Wednesday, but the controversial diabetes pill should be subject to new restrictions due to risky heart side effects.

A panel of Food and Drug Administration advisers voted 20-12 to keep the once blockbuster pill available for diabetics. But 10 panelists also called for limiting who can receive and prescribe the much-debated medication.

The vote marks a tough win for British drugmaker Glaxo, which is facing thousands of lawsuits from patients who say Avandia caused their heart attacks or strokes. While the company may fare better in court due to the panel ruling, sales of Avandia are likely to shrink to minuscule levels.

The FDA is not required to follow the advice of its panelists, though it usually does. FDA officials said they would review the recommendations and make a decision on Avandia as soon as possible.

The vote came despite an earlier ruling by the panel that Avandia appears to increase heart attack risk, underscoring the often contradictory evidence for and against the drug.

Panelists voted 21-4 that Avandia is more likely to cause heart attack than its closest competitor Actos. Eight panelists said there was not enough information to make a decision.

Ultimately though, panelists said the risks were not severe enough to justify removing a drug used by hundreds of thousands of patients.

"I didn't want to take away a drug without definitive evidence that it was bad for those few patients who need it," said University of Missouri Lamont Weide, who voted to leave the drug on the market with new restrictions.

The agency convened the two-day panel meeting to help untangle over 1,000 pages of conflicting evidence about Avandia's risks.

The drug has a long, knotty history at the FDA.

Since diabetics are already predisposed to heart risks it is extremely difficult to tell which heart attacks are drug-related and which are simply caused by the disease.