Heart risks associated with Merck & Co.'s painkiller Vioxx began much sooner than the company has claimed, The Wall Street Journal Online reported on Tuesday, citing a new study.

Merck withdrew Vioxx from the market in September 2004 after a study showed the one-time $2.5 billion-a-year drug doubled the risk of heart problems after 18 months of use. The company has since argued in trials that there is no evidence that short-term use increased heart risks.

But a new study approved for publication in the New England Journal of Medicine says half of patients who experienced cardiovascular events did so within 12 months, the Journal reported. Risk of heart attack and stroke went away within 14 days after patients stopped taking the drug, according to the report.

The new study, known as Victor, was conducted by researchers at Oxford University in England, the Journal said.

Ted Mayer, outside counsel for Merck in the Vioxx litigation, said, We will wait until publication of the study before going into detail about what the data show or do not show.

The reported findings with respect to confirmed thrombotic events in short-term use are not supported by the data found in the other available large placebo studies with Vioxx, Mayer said in a statement.

Merck faced more than 27,000 product liability lawsuits over Vioxx as of March 31, and has said it will try each case individually rather than seek to enter into a broad settlement.

The New Jersey-based drugmaker so far has won nine cases that have gone to trial and lost five.

Merck shares were up 11 cents at $49.68 in early trading on the New York Stock Exchange.