Indivior Plc's experimental drug to treat opioid addiction is effective and should be approved, an advisory panel to the U.S. Food and Drug Administration concluded on Tuesday.

The panel voted 18-1 that the injectable drug, known as RBP-6000, could benefit addicts and the lower of two doses studied has an acceptable safety profile. The FDA typically follows the recommendations of its advisory panels.

"I think this is a really promising alternative to what's out there and will be attractive to a lot of patients," said Laurel Habel, a panelist and researcher at Kaiser Permanente in Oakland, California.

The recommendation comes less than a week after FDA Commissioner Scott Gottlieb announced the agency's plans to encourage widespread use among opioid addicts of less harmful opioids such as methadone and buprenorphine, the active ingredient in RBP-6000.

The United States is battling an opioid abuse epidemic that in 2015 claimed 33,000 people. President Donald Trump recently declared the problem a national public health emergency.


Indivior studied two dosing regimens. In one, 300 milligrams were given once a month for six months. In the other, two doses of 300 milligrams were followed by four doses of 100 milligrams. There was little difference in effectiveness between the two doses and the higher dose caused more side effects.

Panelists said they would like to see more data about which patients should be given the higher dose, though some said they would like to have it available despite the lack of data supporting any additional benefit.

If approved the product would be the first monthly injectable buprenorphine treatment. Indivior already sells Suboxone Film, a product which combines buprenorphine and nalexone and is placed under the tongue or inside the cheek.

The health regulator is due to make its decision on RBP-6000 by Nov. 30.

The drug could capture about 30 percent of the broader buprenorphine market, Stifel's analyst Max Herrmann said. The analyst expects the drug to generate peak sales of $707 million by the end of 2021.

Lund, Sweden-based Camurus AB and privately held Braeburn Pharmaceuticals are also awaiting the health regulator's decision on their weekly and monthly injectable buprenorphine drug, CAM2038.

Herrmann forecast these once-monthly formulations, RBP-6000 and CAM2038, to garner around 50 percent of the buprenorphine market, just short of the 56 percent Suboxone currently enjoys.