A team of Harvard researchers are calling for the US Food and Drug Administration (FDA) to develop guidelines detailing its decision-making process for removing black box warnings from drug labels.
For example, the researchers point to two recent cases where drugmakers petitioned FDA to lift a black box warning from one of their products.
In one case, Pfizer unsuccessfully petitioned FDA to lift a boxed warning for severe psychiatric events, including suicidality, from its smoking cessation drug Chantix. Five years after FDA recommended a boxed warning on the label for Chantix, Pfizer asked the agency to remove the warning based on data from five short-term observational studies.
However, after convening a joint meeting of its Psychopharmacology Drugs and Risk Management Advisory Committees, FDA opted to maintain the black box warning for the drug.
In another case, GlaxoSmithKline (GSK) managed to persuade FDA to remove the black box warning for its blockbuster diabetes drug, Avandia, using an independent analysis of data from a large randomized open-label controlled trial.
In both cases, the researchers say FDA's decision to impose a black box warning was based on less evidence than was necessary to support the removal of a warning. This is necessary, they argue, as FDA must act quickly to protect patients when safety issues emerge.
However, when it comes to removing a warning, the researchers argue that FDA should require more substantial evidence than it used to impose the warning in the first place.
"To avoid frequent flip-flopping, we believe it is ethically justified for the FDA to require a greater burden of proof, or a greater level of certainty provided by the evidence at hand, to justify removal of a boxed warning than it did to impose one," they write.