Safety called a problem for new-generation drugs

Researchers found that most of the warnings came within five years after these biologicals won government approval in the United States and Europe between 1995 and 2007.

Many traditional medicines wind up with safety warnings, too, after they go on the market. But specialists said there were no similar studies of older medicines that made it possible to compare safety issues between the two groups of drugs.

The new study, by Dutch researchers, is the first comprehensive examination of these newer medicines, a driving part of the biotech revolution.

The drugs are known as biologicals because they're made from living material and they typically affect the body's disease-fighting immune system. Many relieve severe symptoms by suppressing that system.

It's that same mechanism that can result in side effects often not seen with traditional chemical-based medicines, said Dr. Charles Bennett, a Northwestern University drug safety specialist. These can include brain and fungal infections and cancer.

Many are genetically engineered. He said that because they typically resemble naturally occurring proteins, many doctors have assumed they were safer than traditional chemical-based medicines. But he said the study shows that's not necessarily true.

"They have an important role," Bennett said. "They're really the next generation of pharmaceuticals."