Merck announced on Sept. 29 a voluntary worldwide withdrawal of Vioxx (rofecoxib), a so-called COX-2 selective nonsteroidal anti-inflammatory drug, or NSAID. A clinical trial revealed a higher risk of cardiovascular events such as stroke and heart attacks. The trial has been halted.

Approved by FDA in 1999 for pain relief, Vioxx has been taken by a total of 84 million patients worldwide and is currently prescribed to 2 million patients, Peter S. Kim, president of Merck Research Laboratories, said in a press conference. Worldwide sales of Vioxx amounted to $2.5 billion last year.

The negative findings were uncovered in the course of a three-year study on whether Vioxx reduces colon polyp recurrence. After 18 months, Kim said, there was a "discernible and confirmed" greater risk of cardiovascular events for patients on Vioxx. Merck continues to seek approval for another COX-2 inhibitor, Arcoxia, in 47 countries, including the U.S.

The firm had been "relatively comfortable" with its 2004 financial guidance, but expects a hit as a result of the Vioxx withdrawal, another in a series of recent setbacks for the company. In early trading on Sept. 30, Merck's stock price dropped by more than 25%.

Despite the lost business--Vioxx accounted for more than 10% of the company's 2003 sales--Merck & Co. CEO Raymond Gilmartin said at the press conference that the company did not intend to change its fundamental strategy.