While most of the generic labels showed relatively small differences from brand-name labeling, 9 percent showed differences of more than 10 side effects. Errors included out-of-date information, incomplete data and, in one case, information for the wrong drug altogether. The causes included missing tables, outdated post-marketing reports and formatting issues (here is the abstract).
"We found that generic drug labels may contain incomplete or incorrect safety information. Until this problem is resolved, physicians and patients should rely on brand drug labeling only, even when the patient is getting a generic version of a drug," Jon Duke, an assistant professor of medicine at the Indiana University School of Medicine, who led the study, says in a statement.
Although the FDA requires bioequivalent drugs to carry identical warnings, the findings are only the latest development to point up the differences that may be found in labeling between brand-name and generic medications.
In a contentious ruling last year, a slim majority of US Supreme Court justices decided that generic drugmakers are not required to strengthen product labeling if alerted to side effects, even when the same change has not been made to the labeling for the branded medications.
As we wrote at the time, the decision came in response to a pair of lawsuits by two women who claimed such changes could have been made under state law and without FDA approval for such changes. They argued generic drugmakers would create uncertainty about safety if they are not held liable under state laws and update labeling in the face of evidence of serious side effects (back story).
Since then, the FDA was petitioned to revise its regulations so generic drugmakers can update product labeling to warn patients about risks associated with their drugs. Under current FDA regulations, generic drugmakers cannot update labeling, even if they become aware of a potential risk not mentioned in the labeling (back story).
The study findings, however, may prompt still more scrutiny not only of the regulations, but of FDA oversight. "Physicians frequently use labeling information, either directly or indirectly, to make prescribing decisions. They need to know about side effects, drug interactions and other safety issues," says Duke.
In reaching their conclusions, the researchers reviewed 9,105 labels for more than 1,500 drugs on DailyMed, an online repository of labeling information maintained by the FDA and the National Library of Medicine. They calculated standard deviations in ADR labeling or each bioequivalent drug and the percent deviation of each generic label from its corresponding brand, according to a statement. They also analyzed the performance of individual generic drugmakers.