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| (Mark One) |                                                                                              |
|------------|---------------------------------------------------------------------------------------------------|
| þ     | Quarterly report pursuant to section 13 or 15(d) of the Securities Exchange Act of 1934 |

| o | Transition report pursuant to section 13 or 15(d) of the Securities Exchange Act of 1934 |
|---|----------------------------------------------------------------------------------------------------|

| Maryland                                                            |   | 33-0724736                                |
|---------------------------------------------------------------------|--------|-------------------------------------------|
| (State or other jurisdiction of incorporation or organization) |   | (I.R.S. Employer Identification No.) |

| 10 North Park Place, Suite 201, Morristown, NJ             |   | 07960                  |
|------------------------------------------------------------|--------|------------------------|
|   (Address of principal executive offices)  |   |   (Zip Code) |

| Large accelerated filer                       | o      | Accelerated filer         | þ |
|-----------------------------------------------|--------|---------------------------|--------|
|                                          |   |                      |   |
| Non-accelerated filer                    | o      | Smaller reporting company | o      |
| (Do not check if a smaller reporting company) |   |                      |

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| ITEM 6. | EXHIBITS |
|---------|----------|

| Exhibit No.        |   | Description                                                                                                                                                                                                                                                                                                                             |
|--------------------|--------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|               |   |                                                                                                                                                                                                                                                                                                                                    |
| 2.1*†‡ |   | Asset Purchase Agreement, dated as of March 10, 2015, between Zogenix Inc., Pernix Ireland Limited, and solely with respect to Sections 5.9.2, 10.2 and 10.14, Pernix Therapeutics Holding Inc.                                                                                                                                         |
| 2.2                |   | Amendment to Asset Purchase Agreement, dated as of April 23, 2015, between Zogenix Inc., Pernix Ireland Limited and Pernix Therapeutics Holding Inc. (incorporated by reference to Exhibit 2.2 to the Company’s Quarterly Report on Form 10-Q filed with the Commission on May 1, 2015)(File Number 001-14494).              |
| 4.1                |   | Third Supplemental Indenture, dated as of April 21, 2015, between Pernix Therapeutics Holdings, Inc. and Wilmington Trust, National Association, as Trustee (incorporated by reference to Exhibit 4.1 to the Company’s  Current Report on Form 8-K filed with the Commission on April 24, 2015)(File Number 001-14494). |
| 4.2                |   | First Supplemental Indenture, dated as of April 21, 2015, between Pernix Therapeutics Holdings, Inc. and U.S. Bank National Association, as Trustee (incorporated by reference to Exhibit 4.2 to the Company’s  Current Report on Form 8-K filed with the Commission on April 24, 2015)(File Number 001-14494).         |
| 4.3                |   | Indenture, dated April 22, 2015, between Pernix Therapeutics Holdings, Inc. and Wilmington Trust, National Association, as Trustee (incorporated by reference to Exhibit 4.3 to the Company’s  Current Report on Form 8-K filed with the Commission on April 24, 2015)(File Number 001-14494).                          |
| 4.4                |   | Forms of 4.25% Convertible Senior Notes due 2021 (included in Exhibit 4.3) (incorporated by reference to Exhibit 4.4 to the Company’s  Current Report on Form 8-K filed with the Commission on April 24, 2015)(File Number 001-14494).                                                                                  |
| 10.1               |   | Consent Solicitation Support Agreement, dated as of April 13, 2015, between the Company and each of the Noteholders party thereto (incorporated by reference to Exhibit 10.1 to the Company’s  Current Report on Form 8-K filed with the Commission on April 16, 2015)(File Number 001-14494).                          |
| 10.2               |   | Inducement Agreement, dated as of April 16, 2015, by and among Pernix Therapeutics Holdings, Inc. and the investors listed on Schedule 1 thereto (incorporated by reference to Exhibit 10.1 to the Company’s Current Report on Form 8-K filed with the Commission on April 17, 2015)(File Number 001-14494).                      |
| 31.1**             |   | Certification of the Registrant’s Chief Executive Officer pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.                                                                                                                                                                                                              |
| 31.2 **       |   | Certification of the Registrant’s Principal Financial Officer pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.                                                                                                                                                                                                          |
| 31.3*              |   | Certification of the Registrant’s Chief Executive Officer pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.                                                                                                                                                                                                              |
| 31.4*              |   | Certification of the Registrant’s Principal Financial Officer pursuant to Section 302 of the Sarbanes-Oxley Act of 2002.                                                                                                                                                                                                          |
| 32.1 ***      |   | Certification of the Registrant’s Chief Executive Officer and Principal Financial Officer pursuant to Section 906 of the Sarbanes-Oxley Act of 2002.                                                                                                                                                                              |
| 101**              |   | Attached as Exhibit 101 to this report are the following items formatted in XBRL (Extensible Business Reporting Language):                                                                                                                                                                                                              |
|               |   | (i) Condensed Consolidated Balance Sheets as of March 31, 2015 and December 31, 2014;                                                                                                                                                                                                                                                   |
|               |   | (ii) Condensed Consolidated Statements of Operations for the Three Months Ended March 31, 2015 and 2014;                                                                                                                                                                                                                                |
|               |   | (iii) Condensed Consolidated Statements of Cash Flows for the Three Months Ended March 31, 2015 and 2014 and                                                                                                                                                                                                                            |
|               |   | (iv) Notes to Condensed Consolidated Financial Statements.                                                                                                                                                                                                                                                                              |

| * | Filed herewith. |
|---|-----------------|

| ** | Previously filed with the Company’s Quarterly Report on Form 10-Q filed by the Company with the Commission on May 1, 2015. |
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| *** | Previously furnished and not “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, with the Company’s Quarterly Report on Form 10-Q filed by the Company with the Commission on May 1, 2015. |
|-----|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| † | Confidential treatment has been requested for portions of this exhibit. These portions have been omitted and filed separately with the Securities and Exchange Commission. |
|---------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ‡ | Schedules omitted pursuant to Item 601(b)(2) of Regulation S-K. The Company agrees to furnish a supplemental copy of any omitted schedule to the Securities and Exchange Commission upon request. |
|---------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

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|                  | PERNIX THERAPEUTICS HOLDINGS, INC. |                                                                                         |
|-----------------------|------------------------------------|----------------------------------------------------------------------------------------------|
|                  |                               |                                                                                         |   |
| Date: August 19, 2015 | By:                                | /s/ DOUGLAS L. DRYSDALE                                                                      |   |
|                  |                               | Douglas L. Drysdale                                                                          |   |
|                  |                               | Chairman and Chief Executive Officer and President and Director(Principal Executive Officer) |   |
|                  |                               |                                                                                         |   |
| Date: August 19, 2015 | By:                                | /s/ SANJAY S. PATEL                                                                          |   |
|                  |                               | Sanjay S. PatelChief Financial Officer                                                       |   |
|                  |                               | (Principal Financial Officer)                                                           |   |

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