FDA Advisory Committee Recommends RBP-6000 For Opioid Use

The Psychopharmacologic Drugs Advisory Committee of the US Food and Drug Administration (FDA) voted 18 to 1 recommending approval of RBP-6000 for the treatment of opioid use disorder, announced Indivior.

The investigational once-monthly injectable buprenorphine formulation is in the ATGIREL delivery system for the treatment of adults with moderate to severe opioid use disorder, and is part of a treatment plan to include counseling and psychosocial support.

“The Advisory Committees’ favorable recommendation of RBP-6000 moves us one step closer to potentially bringing this once-monthly injectable buprenorphine treatment option to patients struggling with opioid use disorder,” Shaun Thaxter, chief executive officer, Indivior, said in a statement. “We are committed to pioneering new options for patients living with this chronic, yet treatable disease to help address the nation’s growing opioid epidemic.”

The endorsement 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 like methadone and buprenorphine — the active ingredient in RBP-6000.

RBP-6000 consists of a polymeric solution of a biodegradable poly-DL-lactide-co-glycolide co-polymer dissolved in N-methyl pyrrolidone (NMP), a water-miscible biocompatible solvent.

After subcutaneous injection, NMP diffuses out of the polymer matrix and the polymer precipitates, trapping buprenorphine inside to form an amorphous solid depot in situ. The depot then releases buprenorphine throughout a 1-month period by diffusion as the polymer biodegrades.

The phase 3 RBP-6000 study met its primary efficacy endpoint with both dosage regimens demonstrating abstinence rates significantly higher than the placebo (300 mg/300 mg, 41.3%; 300 mg/100 mg, 42.7%; placebo, 5%.

Indivior studied 2 dosing regiments: 300 mg given once a month for 6 months, while the other, 2 doses of 300 mg followed by 4 doses of 100 mg.

There was little difference in effectiveness between the doses, although the higher dose caused more side effects.

It was generally well tolerated and had a safety profile consistent of transmucosal buprenorphine except for injection site reactions, which were not treatment limiting and resulted in less than 1% of subjects discontinuing treatment.

The most common adverse effects, reported in greater than 5% of subjects, included constipation, headache, nausea, injection site pruritus, vomiting, increased hepatic enzyme, fatigue and injection site pain.

Based on data from 2016’s National Survey on Drug Use and Health report, 11.8 million Americans engaged in a misuse of opioids in the last year, and 2 million American adults, ages 12 and older, met criteria for opioid use disorder in the last year.

The FDA will consider the non-binding recommendation in its review of the New Drug Application for RBP-6000, submitted on May 30, 2017.

The Prescription Drug User Fee Act (PDUFA) target action date is set for November 30, 2017.

If approved RBP-6000 will be the first monthly injectable buprenorphine treatment.

A press release is made available.