The prescription pain-killer Zohydro (pure hydrocodone in an extended-release formulation) was approved last fall by the FDA against the advice of its own advisory panel. Given the number of people in the U.S. who live with chronic pain (estimated to be around 100 million, though the figure is disputed), and that about half the drug overdose deaths in the U.S. are from prescription painkillers, Zohydro’s launch has drawn its share of attention.

In March, Gov. Deval Patrick of Massachusetts sought to ban Zohydro outright, calling it “a potentially lethal narcotic painkiller,” and 29 state Attorneys General have asked the FDA to reconsider approval. A number of patients had to leave the clinical study because they had serious adverse side effects or didn’t comply with the terms of the trial. Fewer than 300 subjects made it through a full year in the long-term safety trial, and there were five deaths.

Members of the F.D.A. committee who voted against approval acknowledged they were influenced by the drug overdoses claiming more and more lives each year. But they were also disturbed by red flags raised during the clinical trials of Zohydro.

“You still have a 1 percent, almost, death rate from this drug,” said Dr. Jeanmarie Perrone, a committee member from the University of Pennsylvania. What will happen in the doctor’s office, she wondered, where those receiving the drug will not be as carefully screened?