UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or Section 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): February 23, 2015

BioDelivery Sciences International, Inc.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: 919-582-9050

Not Applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation to the registrant under any of the following provisions:

On February 23, 2015, BioDelivery Sciences International, Inc. (the “Company”) issued a joint-press release with Endo International plc (“Endo”) announcing the acceptance by the U.S. Food and Drug Administration (the “FDA”) of a New Drug Application (the “NDA”) for Buprenorphine HCl Buccal Film, to be marketed as BELBUCA^™ (the “Product”) for the management of severe pain. The NDA was a joint submission by the Company and Endo who are developing the Product pursuant to a worldwide license and development agreement between the Company and Endo. A copy of such press release is attached as Exhibit 99.1 hereto.

Also on February 23, 2015, the Company separately announced that the acceptance of the NDA by the FDA triggers a $10 million milestone payment to the Company from Endo. A copy of such press release is attached as Exhibit 99.2 hereto.

Cautionary Note Regarding Forward-Looking Statements

This Current Report on Form 8-K, the press release included herein, and any statements of representatives and partners of BioDelivery Sciences International, Inc. (the “Company”) related thereto contain, or may contain, among other things, certain “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995. Such forward-looking statements involve significant risks and uncertainties. Such statements may include, without limitation, statements with respect to the Company’s plans, objectives, projections, expectations and intentions and other statements identified by words such as “projects,” “may,” “will,” “could,” “would,” “should,” “believes,” “expects,” “anticipates,” “estimates,” “intends,” “plans,” “potential” or similar expressions. These statements are based upon the current beliefs and expectations of the Company’s management and are subject to significant risks and uncertainties, including those detailed in the Company’s filings with the Securities and Exchange Commission. Actual results (including, without limitation, the results of the Company’s NDA application, and FDA review of the NDA application, for Buprenorphine HCl Buccal Film) may differ significantly from those set forth in the forward-looking statements. These forward-looking statements involve certain risks and uncertainties that are subject to change based on various factors (many of which are beyond the Company’s control). The Company undertakes no obligation to publicly update any forward-looking statements, whether as a result of new information, future events or otherwise, except as required by applicable law.

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has caused this report to be signed on its behalf by the undersigned hereunto duly authorized.