The heart problems associated with the painkiller Vioxx increase soon after beginning treatment, says a new study published in the New England Journal of Medicine that contradicts assertions by the drug's manufacturer.  

Researchers looked at 2,434 patients with stage 1 or stage 2 colorectal cancer, half of whom were taking 25 mg daily rofecoxib, sold under the brand name Vioxx.

The patients were taking Vioxx for an average of just 7.4 months before the trial was suddenly early, because of worldwide warnings about the increased heart risk from Vioxx.

An analysis of the trial found that of 23 heart & circulation problems that occurred during the study period, 16 happened while the patients were taking Vioxx or within two weeks of stopping treatment. This suggests an estimated risk for heart and circulation problems of 2.6 times greater for Vioxx over placebo.

Four of the patients in the Vioxx group died of the cardiovascular event. And six more incidents were reported among in the rofecoxib group within two years after the trial ended.

Vioxx was prescribed primarily for arthritis pain relief. Its manufacturer, Merck & Co., pulled the drug from the market in September 2004 after research showed it doubled risk of heart attacks and strokes in patients who took the drug for more than 18 months.

That triggered an avalanche of lawsuits -- more than 27,000 so far.