Side effects appear after drugs get OK, research suggests

CHICAGO -- New research estimating that 20 percent of recently approved prescription drugs have serious and even life-threatening side effects suggests doctors should prescribe older medication whenever possible.

"It's like playing Russian roulette when a doctor prescribes a newly approved drug that doesn't have a big breakthrough," said Dr. Sidney Wolfe of Public Citizen Health Research Group, a co-author of the study.

The findings, published in Wednesday's Journal of the American Medical Association, should prompt the Food and Drug Administration to consider raising its threshold for approving new drugs when safe and effective alternatives exist, the researchers said. They said pressure from pharmaceutical companies and doctors' failure to closely read warning labels are partly to blame.

An accompanying editorial by two FDA experts said the analysis overstates the problem.

Safety studies that are conducted before a drug wins approval typically involve a few thousand patients and may not detect all side effects, especially relatively rare ones, Drs. Robert Temple and Martin Himmel said.

"Frequent post-marketing label changes are therefore inevitable and should be anticipated," they wrote.

Temple also noted that some medications cause side effects in only certain groups of patients, such as pregnant women, which does not mean a drug is dangerous for everyone.

The researchers analyzed 548 drugs approved from 1975 through 1999.

Most troublesome new drugs do not represent any advance in treatment and are at best no better than older, safer drugs already on the market, he said.

The study analyzed what are known as "black-box" warnings published in the Physicians Desk Reference, a compendium of drugs and labeling information published annually. The warnings highlight the most serious side effects. Sixteen drugs studied were taken off the market, about half of them two years after winning FDA approval.