Vioxx Case Illustrates Dual Nature of Drugs Researchers Also Discover Positive Side

In one of the great examples of the mixed messages of science, the same study that killed the blockbuster arthritis drug Vioxx after showing that it had heart risks also found that the drug had a significant benefit: It prevented precancerous colon polyps in some patients, one of the study's principal researchers said.

But the drug's maker, Merck, and the researcher, Dr. Robert Bresalier, said that neither Merck nor the researchers had known that Vioxx prevented polyps when Merck stopped the study and withdrew the drug from the market.

"At the time we made our decision to voluntarily withdraw Vioxx, the study had not yet been completed, and efficacy results had not been disclosed to Merck by the study's steering committee," Christopher Loder, a Merck spokesman, said.