Maker of buprenorphine implant releases encouraging study data

The developer of a subdermal implant of buprenorphine lasting six months appears to be on course for resubmission of a New Drug Application (NDA) for approval of the formulation, given this week's release of positive results from a Phase 3 double-blind study involving 177 patients.

The study findings, formally released in a June 8 conference call, state that Titan Pharmaceuticals' Probuphine implant led to increased treatment response and fewer opioid-positive drug screens when compared with daily sublingual buprenorphine/naloxone tablets. Titan and development partner Braeburn Pharmaceuticals in 2013 saw their NDA for Probuphine rejected by the Food and Drug Administration (FDA), partly over concerns about the surgical insertion procedures for the formulation.

The companies intend to resubmit an application later this year. Because the formulation is still considered to be under priority review status by the FDA, the maker of the drug is hoping to win approval in the first half of 2016.

“Probuphine holds great promise, not just because of its potential for treating opioid addiction, but also because, as a six-month implant, it allows patients to resume their lives without the constant reminder of their addiction,” Genie L. Bailey, MD, a study co-investigator and clinical associate professor of psychiatry and human behavior at Brown University's Warren Alpert Medical School, said in a Titan news release.

The study found response rates of 96.4% in the Probuphine group and 87.6% in the sublingual buprenorphine/naloxone group, with response defined as at least four of six months opioid-free based on drug testing and self-report. Also, 88% of Probuphine patients had six full months of negative urine tests over the course of the study, compared with 72% of the buprenorphine/naloxone patients.

The medication groups showed no differences in symptoms of opioid withdrawal and in cravings. An implant site adverse event (the implant is usually placed in the upper arm) occurred in 23% of Probuphine patients, with most of these cases considered mild in severity, the company reported.