As filed with the Securities and Exchange Commission on December 18, 2014

Registration No. 333-      

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C.  20549

FORM S-8

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

SUPERNUS PHARMACEUTICALS, INC.

(Exact name of registrant as specified in its charter)

Amended and Restated 2012 Equity Incentive Plan

Amended and Restated 2012 Employee Stock Purchase Plan

(Full title of the plan)

Jack A. Khattar

President and Chief Executive Officer

Supernus Pharmaceuticals, Inc.

1550 East Gude Drive

Rockville, Maryland 20850

(301) 838-2500

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copy of all communications to:

Mark I. Gruhin, Esquire

Saul Ewing LLP

1919 Pennsylvania Avenue, N.W.
Suite 550
Washington, DC 20006-3434
(202) 342-3444

See next page for calculation of registration fee.

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

CALCULATION OF REGISTRATION FEE

EXPLANATORY NOTE

Pursuant to General Instruction E of Form S-8, this Registration Statement is being filed in order to effect the registration of (i) an additional 1,500,000 shares of Common Stock of Supernus Pharmaceuticals, Inc. (the “Registrant”) under the Registrant’s Amended and Restated 2012 Equity Incentive Plan and (ii) an additional 250,000 shares of Common Stock under the Registrant’s Amended and Restated 2012 Employee Stock Purchase Plan.

The contents of the Registration Statement on Form S-8 filed by the Registrant on May 17, 2012 (File No. 333-181479) are hereby incorporated by reference.

PART II
INFORMATION REQUIRED IN THE REGISTRATION STATEMENT

Item 8.   EXHIBITS.

The following is a list of exhibits filed with, or incorporated by reference into, this Registration Statement:

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SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Rockville, State of Maryland, on December 18, 2014.

POWER OF ATTORNEY

KNOW ALL MEN BY THESE PRESENTS, that each person whose signature appears below hereby makes, constitutes and appoints Jack A. Khattar and Gregory S. Patrick, and each of them, with full power to act without the other, his true and lawful attorney-in-fact and agent, with full power of substitution and resubstitution, for him and in his name, place and stead, in any and all capacities to sign any and all amendments to this Registration Statement, including post-effective amendments, and to file the same, with all exhibits thereto, and other documents in connection therewith, with the Securities and Exchange Commission, granting unto said attorneys-in-fact and agents, and each of them, full power and authority to do and perform each and every act and thing requisite or necessary to be done in connection therewith, as fully to all intents and purposes as he might or could do in person, hereby ratifying and confirming all that said attorneys-in-fact and agents or any of them, or any substitute or substitutes, may lawfully do or cause to be done by virtue hereof.

Pursuant to the requirements of the Securities Act of 1933, this registration statement has been signed below by the following persons in the capacities and on the date indicated.

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EXHIBIT INDEX

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EXHIBIT 5.1

December 18, 2014

Supernus Pharmaceuticals, Inc.

1550 East Gude Drive

Rockville, Maryland 20850

Gentlemen:

We refer to the Registration Statement on Form S-8 (the “Registration Statement”) of Supernus Pharmaceuticals, Inc., a Delaware corporation (the “Company”), to be filed with the Securities and Exchange Commission covering the registration under the Securities Act of 1933, as amended (the “Securities Act”), of 1,750,000 shares of common stock, par value $0.001 per share, of the Company (the “Shares”) authorized pursuant to the Amended and Restated 2012 Equity Incentive Plan and the Amended and Restated 2012 Employee Stock Purchase Plan (hereinafter referred to collectively as the “Plans”).

We have examined the Registration Statement, the Certificate of Incorporation and By-Laws of the Company and such records, certificates and other documents as we have considered necessary or appropriate for the purposes of this Opinion.

The opinions expressed below are limited to the Delaware General Corporation Law.

Based on the foregoing, it is our opinion that:

1.              the Company is duly organized, validly existing and in good standing under the laws of the State of Delaware; and

2.              the issuance of the Shares has been duly authorized and, when issued in accordance with the terms of the Plans, the Shares will be duly and validly issued, fully paid and non-assessable.

We hereby consent to the use of our name in the Registration Statement as counsel who will pass upon the legality of the Shares for the Company and as having prepared this Opinion as an exhibit to the Registration Statement. In giving the foregoing consent, we do not thereby admit that we are in the category of persons whose consent is required under Section 7 of the Securities Act or the rules and regulations of the Securities and Exchange Commission thereunder.

EXHIBIT 23.1

Consent of Independent Registered Public Accounting Firm

We consent to the incorporation by reference in the Registration Statement (Form S-8 No. 333-00000) pertaining to the Amended and Restated 2012 Equity Incentive Plan and the Amended and Restated 2012 Employee Stock Purchase Plan of Supernus Pharmaceuticals, Inc. of our report March 21, 2014, with respect to the consolidated financial statements of Supernus Pharmaceuticals, Inc. included in its Annual Report (Form 10-K) for the year ended December 31, 2013, filed with the Securities and Exchange Commission.