Among the 467,809 cases reported during the eight years covered, 51 drugs accounted for almost half of these cases.
Safety experts are criticizing the voluntary system that reports side effects, saying that many rare and unexpected consequences of prescription drug use are missed because doctors fail to link their patients' conditions to their medication. Now, U.S. lawmakers are considering legislation that would call on the Food and Drug Administration to use databases like those of insurance companies to more systematically detect harmful side effects.
Says lead researcher Thomas Moore of the Institute for Safe Medication Practices, a non-profit group in Pennsylvania: "Substantially growing numbers of patients are experiencing serious injuries from drug therapy.
"The existing system is not adequately protecting patients and underscores the importance of recent reports urging far-reaching legislative, policy, and institutional changes.''
Coming to solid figures, more than 15,000 people died from drug reactions in 2005, compared with 5,519 people in 1998, the researchers say. Most of the fatalities were linked to generic pain pills like Teva Pharmaceutical Industries Ltd.'s generic oxycodone, fentanyl, morphine and acetaminophen (sold without a prescription by Johnson & Johnson as Tylenol).
A total of 89,482 serious side effects from drug treatment were reported to the FDA in 2005, more than 2 1/2 times the 34,966 reported in 1998, the study also found. About 1,500 drugs had reported side effects.
The voluntary system of reporting works by reports from doctors and other health-care providers directly to the FDA or to the companies that make the medications, about these drugs. The manufacturers are required to forward any information they receive on the unintended consequences of their drugs (including deaths, birth defects, disabilities and hospitalizations) to the FDA.
Among the drugs causing the most nonfatal adverse events were estrogens, insulin, interferon beta, Paroxetine, Clozapine, Oxycontin, warfarin and Fentanyl. Paroxetine is an antidepressant, interferon beta is used to treat multiple sclerosis and cancer, and warfarin is an anti-clotting agent.
Moore said he was particularly disturbed by the appearance of drugs such as insulin and warfarin on the list.
"We have drugs out there we know how to manage, whose risks are well-known, and for which we don't have adequate programs in place to manage those risks," he said.
Estrogen, sold by Wyeth as Premarin and Prempro, was one of the medications with 500 or more reported serious adverse events in a single year. The hormones were the subjects of 3,996 reports in 2004, two years after the Women's Health Initiative found estrogen replacement therapy increased the risk of heart complications. A year before the report, there were 617 side- effect reports on estrogen.
Says Ken Johnson, senior vice president of the Pharmaceutical Research and Manufacturers of America: "Although there is always room for improvement, the U.S. has the world's best drug safety record.
"As a result of the combined efforts of FDA and pharmaceutical research companies, only about 3 percent of prescription medicines have been withdrawn from the American market for safety reasons over the last 20 years.''