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Buprenorphine implant edges closer to approval

March 25, 2013
by Gary A. Enos, Editor
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Developers of a subdermal implant version of the opioid addiction medication buprenorphine reached a milestone last week that could lead to federal approval of their treatment sometime this year.

The Food and Drug Administration’s (FDA’s) 15-member Psychopharmacologic Drugs Advisory Committee on March 21 voted 10-4 (one abstention) in favor of approval of the long-acting treatment known as Probuphine. The FDA is not bound by its advisory panel’s recommendation in rendering its final decision on whether to approve Probuphine for the treatment of opioid dependence.

The FDA granted priority review status for the under-the-skin implant, which is normally placed in the patient’s upper arm area in a medical office procedure, with a target action date of April 30. California-based Titan Pharmaceuticals submitted a New Drug Application for Probuphine last October, and drug manufacturer Braeburn Pharmaceuticals is its partner on the project.

In a conference call held the day after the advisory panel met last week to review and act on data regarding Probuphine, officials with Titan Pharmaceuticals indicated that the major hurdle they still have to clear involves a Risk Evaluation and Management Strategy (REMS) program for the treatment.

Titan executive chairman Marc Rubin, MD, referred to the REMS-related discussions with the FDA as a “dynamic” process during the March 22 conference call, in which several investment experts asked questions of company officials. There have been lingering questions about site irritations experienced by a small number of patients in clinical trials, as well as about medical professionals’ degree of comfort in performing the implant procedures.

As evidence of Rubin’s characterization, the advisory committee last week was largely divided on the REMS program for the treatment, with 6 members abstaining from a vote on the program, 5 voting in favor of it and 4 opposed. The advisory panel’s separate votes on the safety and effectiveness of Probuphine were similar to its vote on the overall recommendation for FDA approval.

Placebo-controlled research published in 2011 in the Journal of the American Medical Association (JAMA) reported that Probuphine treatment over 24 weeks offered statistically significant benefits in a group of 163 patients. Also, a confirmatory study of 287 patients, with results reported in 2011, reported that Probuphine was not inferior to the sublingual tablet formulation of buprenorphine, according to Titan.

The possible emergence of a subdermal implant comes at a time when the manufacturer of the original tablet formulation of buprenorphine for opioid dependence, Reckitt Benckiser Pharmaceuticals, is moving exclusively to use of sublingual film as its patent protection on Suboxone expires and as makers of generic alternatives to Suboxone enter the market.

The subdermal implant is designed to deliver continuous blood levels of buprenorphine for six months following one treatment, thus offering a potential advantage in patient retention in treatment. Titan executive vice president and chief development officer Katherine Glassman-Beebe, PhD, said in the March 22 conference call that prescriber training in the process of administering the implant would likely take place through regional workshop sessions.

Titan president Sunil Bhonsie said in the conference call that if the implant receives FDA approval, “We expect Probuphine to be a transformative treatment for opioid dependence.”

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