Fentanyl, a highly dangerous painkiller at the heart of the US opioid epidemic, has been overprescribed by doctors, according to a report Tuesday that accused health authorities and manufacturers of being too lax in their oversight.   
The drug is a synthetic opioid up to 100 times more powerful than morphine and which is largely sold on the black market. 
But it is prescribed in certain cases of cancer under what are supposed to be very tight restrictions, in the form of lozenges, lollipops or sprays under the tongue. It is supposed to be used only on cancer patients for whom other opioid painkillers have been insufficent.
The report in Journal of the American Medical Association, or JAMA, said that this was not the case, however.
The investigation, carried out by experts from Johns Hopkins University, said that of the thousands of patients who had been prescribed fentanyl, between a third and half of them should never have received the drug. 
One doctor in five did not know that fentanyl was only supposed to be used by opioid-tolerant cancer patients, the researchers found. 
As a result, it has been wrongly prescribed for far less serious conditions like lower back pain or chronic headaches.
‘The drug can kill you,’ said one of the authors of the report Caleb Alexander, co-director at the Center for Drug Safety and Effectiveness at Johns Hopkins.
‘There’s no question that individuals have died from inappropriate prescribing of these products,’ he said.
‘The whole point of this program was to prevent exactly the use that commonly occurs,’ he said of fentanyl, which has become the deadliest drug in an epidemic that killed 70,000 people in the United States in 2016.
The team of researchers battled for four and a half years to get 5,000 pages of documents on the fentanyl program from the FDA. 
Legally, doctors are allowed to prescribe a drug for an ailment other than the one it is indicated for. The role of the FDA is to regulate the laboratories that make the drugs, not the doctors.
But as part of their oversight responsibility, manufacturers ‘were supposed to monitor and potentially disenroll prescribers who violated the terms of the program. And yet not a single prescriber was identified and disenrolled,’ said Alexander.
An FDA spokesperson said the agency shared the concerns raised in the report.
‘The FDA will soon be sharing planned next steps … to make sure the program is working to mitigate the risks of these medicines and that they’re prescribed only to opioid-tolerant patients,’ the spokesperson said.