Many approved U.S. drugs show side effects

CHICAGO — Almost one-third of new drugs approved by U.S. regulators over a decade ended up years later with warnings about unexpected, sometimes life-threatening side effects or complications, a new analysis found.

The results covered all 222 prescription drugs approved by the U.S. Food and Drug Administration from 2001 through 2010. The researchers looked at potential problems that cropped up during routine monitoring that’s done once a medicine is on the market. The 71 flagged drugs included top-sellers for treating depression, arthritis, infections and blood clots. Safety issues included risks for serious skin reactions, liver damage, cancer and even death.

“The large percentage of problems was a surprise,” and they included side effects not seen during the review process, said Dr. Joseph Ross, the study’s lead author and an associate professor of medicine and public health at Yale University.

While most safety concerns were not serious enough to prompt recalls, the findings raise questions about how thoroughly drugs are tested before approval, said drug safety expert Thomas Moore. But Ross said the results suggest the FDA “is kind of doing a great job” at scrutinizing drugs after approval.

New drugs are generally tested first in hundreds or even thousands of people for safety and effectiveness.

“We know that safety concerns, new ones, are going to be identified once a drug is used in a wider population. That’s just how it is,” Ross said. “The fact that that’s such a high number means the FDA is working hard to evaluate drugs and once concerns are identified, they’re communicating them.”

The researchers analyzed online FDA data on new drugs and the agency’s later safety announcements. Problems surfaced on average about four years after approval. Results were published Tuesday in the Journal of the American Medical Association.

Among the drugs with added warnings: Humira, used for arthritis and some other illnesses; Abilify, used for depression and other mental illnesses; and Pradaxa, a blood thinner. The withdrawn drugs and the reason: Bextra, an anti-inflammatory medicine, heart problems; Raptiva, a psoriasis drug, rare nervous system illness; and Zelnorm, a bowel illness drug, heart problems.