An outside panel of expert advisers to the U.S. Food and Drug Administration declined to recommend approval of Trevena Inc.'s intravenous opioid oliceridine.

At an Oct. 11 meeting, the FDA's Anesthetic and Analgesic Drug Products Advisory Committee narrowly rejected the drug in an 8-to-7 vote against approval.

The FDA, which is not bound by the committee's vote, is expected to make a decision by Nov. 2.

Trevena President and CEO Carrie Bourdow said her company would work with the FDA as the agency completes its review of oliceridine.

"We continue to believe that the totality of evidence presented and discussed today supports the utility of oliceridine as a new analgesic option for the management of moderate to severe acute pain for patients in hospitals or other controlled clinical settings," Bourdow said in a statement after the FDA meeting.

The committee had reviewed data from three phase 3 studies of oliceridine. But panelists raised concerns about the lack of efficacy and safety data.

The FDA's internal review of the studies found that morphine demonstrated a greater reduction in pain intensity than oliceridine. The regulator also questioned whether Trevena's safety database for oliceridine was adequate to support the proposed dosing.

At the meeting, regulators emphasized that oliceridine had a high potential for dependence, overdose and abuse.

Trevena is seeking approval of its opioid at the height of the U.S. addiction and overdose crisis — an epidemic that killed 72,000 Americans last year.

Regulators also raised concerns about the complex dosing for oliceridine in the hospital setting.

In addition, the FDA noted there were other safety concerns with oliceridine, including adverse liver events and a heart rhythm disorder known as QT prolongation.

Review revelations

Documents the FDA made public earlier this week also revealed that Trevena may have misled investors about what regulators told the company in 2016 about its studies of the drug.

In a May 2, 2016, statement, Trevena called the meeting it held with the FDA a little over a month earlier "successful" and said it had reached a general agreement with regulators on key elements of oliceridine's phase 3 program to support a new drug application for the drug.

Then-CEO Maxine Gowen, who was replaced as company chief Oct. 1 with Bourdow, said she was "very pleased with the outcome of our end-of-phase 2 discussion with the FDA."

But the FDA told a different story in its Oct. 9 documents.

At the March 29, 2016, end-of-phase 2 meeting, the FDA told Trevena that the agency did not agree with the proposed dosing in the company's phase 3 studies, according to the agency's account.

The FDA also said it did not agree with Trevena's proposed primary endpoint, nor did regulators agree with the company's proposed noninferiority margin for comparing morphine to oliceridine.