The benefits of Endo International Plc's long-acting opioid painkiller no longer outweigh its risks, an independent panel to the U.S. Food and Drug Administration (FDA) concluded on Tuesday.
Endo's shares closed down about 4 percent and were down about 1.7 percent in extended trading.
Opioid abuse, overdose and addiction have assumed epidemic proportions in the United States, partly due to unrestricted prescription of narcotic painkillers as well as the paucity of access to substance-abuse treatment programs.
The panel was called to upon to address the high abuse rate of Endo's Opana ER — a long-acting variation of oxymorphine — and other oxymorphone products.
Initially approved in 2006, a new formulation of Opana ER designed to deter abuse hit the market in 2012.
However, data shows that while nasal abuse has reduced with the reformulation, rates of intravenous abuse increased, FDA staff noted in their review on Thursday, acknowledging that it was unclear whether that rise was tied directly to the reformulation.
This trend was apparent before the reformulation hit the market, and abuse rates are similarly high for oxymorphone generics, they said.
Of particular concern is the increased rate of certain rare blood disorders and HIV that are linked to the intravenous abuse of the reformulation, panelists said on Tuesday.
Since the introduction of the new Opana formulation, a number of opioids with abuse-deterrent labels have been approved by the FDA.
Eighteen panelists recommended that the risks of the reformulation eclipse the benefits, while eight disagreed and one member abstained from voting.
Panelists expressed concerns that the voting question posed to them did not expect them to evaluate the risk-benefit profile for the intended user, versus an addict.
Some questioned whether withdrawing the product would stop an addict from abusing other opioids, or whether oxymorphone was still an integral part of the arsenal of treatments for chronic pain.
The FDA typically follows the recommendations of the panel but is not obliged to do so. It could choose to change the product's labeling, restrict prescribing and/or remove it from the market altogether.
As long as oxymorphone is still on the market Opana will still benefit patients, because otherwise they'll just move on to generic oxymorphone that has no abuse-deterrant properties, panelist Ronald Litman said.
"I voted yes, but I strongly believe there is no place for oxymorphone in American society today - but that's not what you asked me."
(Reporting by Natalie Grover in Bengaluru; Editing by Maju Samuel and Shounak Dasgupta)