The researchers found that the weak oversight occurred just as the opioid crisis was taking root and tens of thousands of people were dying from overdoses every year, according to The New York Times.

The researchers at the Johns Hopkins Bloomberg School of Public Health looked at nearly 10,000 pages of FDA documents about the agency's "risk evaluation and mitigation strategy," which it launched in 2012 to address the risks that accompanied extended-release and long-acting opioids, as CNN reported.

Although these drugs "can be clinically useful among appropriately selected patients, they have also been widely oversupplied, are commonly used nonmedically, and account for a disproportionate number of fatal overdoses," the authors wrote, as CNN reported.

The FDA did ask the makers of OxyContin and other highly addictive long-acting painkillers for safety training for the more than half the physicians prescribing the opioids in 2011. The FDA also asked the drug makers to track the efficacy of their training and steps they are taking to reduce addiction and overdoses, as The New York Times reported. However, the FDA was never able to determine if their request was effective because the drug makers failed to collect the proper data.

The researchers found that when the FDA realized through its own review that it was apparent the drug makers were not tracking their training regimen correctly, the agency still did not demand improvement to the risk evaluation and mitigation strategy program, as The New York Times reported.

The study found that after more than five years after implementation, the FDA had no ability "to assess whether these outcomes were achieved," as CNN reported.

"What's surprising here is the design of the program was deficient from the start," said Caleb Alexander, the senior author of the study, who serves as a paid expert witness in litigation against opioid manufacturers and distributors, according to The New York Times. "It's unclear why the FDA didn't insist upon a more scientifically rigorous evaluation of this safety program."

The FDA was aware that allowing the drug companies to fund the analysis of their training was providing insufficient and missing data. A 2013 inspector general report said the agency "lacks comprehensive data to determine whether risk evaluation and mitigation strategies improve drug safety." Furthermore, a 2016 FDA advisory committee "noted methodological concerns regarding these studies," according to the authors, as CNN reported.

The study found that the agency is a ripe target for criticism after refusing to take swift and effective action as a crisis was growing.

"FDA has tools that could mitigate opioid risks more effectively if the agency would be more assertive in using its power to control opioid prescribing, manufacturing, and distribution," said retired FDA senior executive William K. Hubbard in an editorial that accompanied the study, as CNN reported. "Instead of bold, effective action, the FDA has implemented the Risk Evaluation and Mitigation Strategy programs that ... do not even meet the limited criteria set out by the FDA."

Hubbard continued that the FDA has the ability to place tight restriction on opioid distribution, but it has dragged its feet in doing that, as CNN reported.

Other critics of the government's response to opioid crisis echoed Hubbard's sentiments. Andrew Kolodny, the co-director of opioid policy research at the Heller School for Social Policy and Management at Brandeis, told The New York Times that the risk evaluation and mitigation strategy program was "a really good example of the way FDA has failed to regulate opioid manufacturers. If FDA had really been doing its job properly, I don't believe we'd have an opioid crisis today."