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# FDA Backpedals on Alkermes NDA Filing Rufusal
- URL: https://www.fdaweb.com/fda-backpedals-on-alkermes-nda-filing-rufusal/
- Published: 2018-04-16T12:00:00.000Z
- Updated: 2026-09-14T23:59:07.000Z
- Author: David McFarland
- Tags: Drugs, #legacy-id-D5141232

FDA has rescinded an Alkermes refuse-to-file letter issued late last month on its NDA for ALKS 5461 (buprenorphine and samidorphan) an investigational drug for adjunctive treatment of major depressive disorder in patients with an inadequate response to standard antidepressant therapies. In doing so, the agency has now accepted the submission for review and set a user fee target action date of 1/31/2019\. The company says that it recently met with agency reviewers following the 3/30 letter and “clarified certain aspects of the NDA submission. No additional data or analyses were submitted by Alkermes to FDA.”

The refusal letter (see earlier story) said the agency was unable to complete a substantive review of the regulatory package, based on insufficient evidence of overall effectiveness for the proposed indication, and that additional well-controlled clinical trials were needed prior to resubmission. In addition, the agency requested a bioavailability study to generate additional bridging data between ALKS 5461 and the reference listed drug, buprenorphine. At the time, Alkermes said it strongly disagreed with FDA’s position and it planned to appeal the decision.

ALKS 5461 acts as an opioid system modulator and represents a novel mechanism of action for the adjunctive treatment of major depressive disorder in patients with an inadequate response to other therapies, Alkermes says.