Merck & Co is in the dock again after a damaging report by the Associated Press which claims the firm was looking to reformulate its now-withdrawn blockbuster painkiller Vioxx (rofecoxib) to reduce cardiovascular side effects in 2000, over four years before the drug was finally recalled [[01/10/04a]].

After a study in March 2000 found that patients taking Vioxx were five times more likely to have heart attacks than individuals using naproxen, Merck said that this was a result of the latter’s cardioprotective properties and not any defect in Vioxx. However, AP is claiming that Merck researchers were considering combining Vioxx with another agent to reduce the risk of heart attacks and strokes and filed an application with the US Patent Office in 2001 to combine the drug with a thromboxane inhibitor, though the project was later dropped.

The news agency goes on to add that it received a document containing this information, which had been mistakenly provided by Merck to plaintiff lawyers in one of the thousands of lawsuits the company is facing over Vioxx.

Law firm Hughes Hubbard & Reed, which is representing Merck in Vioxx product-liability litigation, confirmed that the company had filed such a patent application but stated that it “has nothing to do with Merck’s firm belief in the cardiovascular safety of Vioxx, both before the medicine was approved by the US Food and Drug Administration and right up until Merck voluntarily withdrew Vioxx from the market.”

News of the AP story meant that Merck shares slipped a couple of percentage points and the damage to the company could be considerable given that much of the basis of the lawsuits is that the company hid Vioxx’s risks. Merck has not yet commented officially on the AP story, but the news agency says a lawyer for the firm declined to talk the specifics of the document, stating that it was a privileged internal company discussion.