EXECUTIVE EMPLOYMENT AGREEMENT

Exhibit 10.3

MIDDLEBROOK PHARMACEUTICALS, INC.

EXECUTIVE EMPLOYMENT AGREEMENT

     THIS EXECUTIVE EMPLOYMENT AGREEMENT (this “ Agreement ”) is made this 1st day of July, 2008 by and between John S. Thievon, a resident of Denton County, Texas, (the “ Employee ”), and MiddleBrook Pharmaceuticals, Inc., a corporation organized and existing under the laws of the State of Delaware and formerly known as Advancis Pharmaceutical Corporation (the “ Company ”).

BACKGROUND

     WHEREAS, the Company is engaged in the business of developing, improving and promoting antibiotic therapies and the delivery and dosage of antibacterials, as well as extending the market and patent life of important anti-infectives and oncological agents (as may be modified or expanded by the Company during the term of this Agreement, collectively and individually, the “ Business ”); and

     WHEREAS, concurrently with the execution of this Agreement, Equity Group Investments, LLC (“ EGI ”) and the Company are entering into a Securities Purchase Agreement of even date herewith (the “ Purchase Agreement ”), pursuant to which the parties thereto have agreed, upon the terms and subject to the conditions set forth therein, that the Company will sell to EGI (i) 30,303,030 shares of the authorized but unissued shares of common stock, $0.01 par value per share, of the Company (the “ Common Stock ”) and (ii) a warrant to purchase an aggregate of 12,121,212 shares of Common Stock (such transaction known as the “ Transaction ”); and

     WHEREAS, the Company desires to employ the Employee and the Employee desires to be employed by the Company, upon the terms and conditions set forth in this Agreement.

     NOW, THEREFORE, in consideration of the mutual covenants and obligations contained herein, and intending to be legally bound, the parties, subject to the terms and conditions set forth herein, agree as follows:

     1.  Employment and Term . The Company hereby employs the Employee and the Employee hereby accepts employment with the Company, as President and Chief Executive Officer (the “ Position ”), effective as of the Closing Date of the Transaction (the “ Commencement Date ”), and contingent upon the Closing of the Transaction. The “ Closing ” and the “ Closing Date ” shall have the definitions assigned to such terms in the Purchase Agreement. Employee is employed by the Company on an at will basis. The Employee shall be entitled to terminate this Agreement at any time upon ninety (90) days prior written notice to the Company. The Company shall be entitled to terminate this Agreement at any time subject to the provisions of Section 8 hereof. (The entire period of time during which the Employee is employed by the Company is referred to herein as the “ Term ”).

     2.  Duties . During the Term, the Employee shall serve the Company faithfully and to the best of his/her ability and shall devote his/her reasonable and prudent attention, skill and efforts to the performance of the duties required by or appropriate for the Position. Subject to the oversight of the Board of Directors of the Company (the “ Board of Directors ”), the Employee shall have the duties and responsibilities customarily associated with the Position, including such duties and responsibilities as may be assigned to him/her from time to time by the Board of Directors. The Employee shall perform such duties and responsibilities at the Company’s facility located in Germantown, Maryland or at such other location as may be mutually agreed upon by the Company and the Employee in accordance with the business needs of the Company. The Employee, as President and Chief Executive Officer shall report to the Board of Directors. The Employee, as Chief Executive Officer, will be elected to the Board of Directors in accordance with past practice.

     3.  Other Business Activities . Except with the prior written consent of the Company in its sole discretion, the Employee shall not engage, directly or indirectly, during the Term, in any other business activities or pursuits whatsoever, except activities in connection with charitable or civic activities, his position on the board of directors of DaySpring Pharma, LLC, personal investments and serving as an executor, trustee or in other similar fiduciary capacity; provided that any such activities do not interfere with the performance of his/her responsibilities and obligations pursuant to this Agreement.

     4.  Compensation . The Company shall pay the Employee, and the Employee hereby agrees to accept, as compensation for all services to be rendered to the Company and for the Employee’s intellectual property covenants and assignments and covenant not to compete, as provided in Sections 6 and 7 hereof, the compensation set forth in this Section 4.

          4.1 Salary . The Company shall pay the Employee a base salary at the annual rate of Five-Hundred Thousand USD ($500,000) (as the same may hereafter be adjusted, the “ Salary ”) during the Term of this Agreement. The Salary shall be inclusive of all applicable income, social security and other taxes and charges that are required by law to be withheld by the Company (collectively, “ Taxes ”) and shall be paid and withheld in accordance with the Company’s normal payroll practice for its executive employees from time to time in effect. The Salary shall be subject to increase at the option and in the sole discretion of the Company based upon the demonstrated performance of the Employee.

          4.2 Bonus . The Employee shall be eligible to be awarded an annual cash bonus (the “ Annual Bonus ”), which bonus shall be determined by the Board of Directors and shall be at a target amount of Fifty-Five percent (55%) of Salary paid during such applicable period, less Taxes, provided that the Employee shall have achieved all of his/her performance objectives established for such period. Such bonus shall be determined and paid no later than the 15 ^th day of the third month of such succeeding calendar year.

          4.3 Initial Option Award . Immediately following the Commencement Date, and contingent upon the Closing of the Transaction, the Employee shall receive an option to purchase Common Stock under the equity-based incentive compensation plans adopted by the Company for which senior executives are generally eligible. The amount of Common Stock subject to such option shall equal Two and Twenty-Five Hundredths percent (2.25%) of all

issued and outstanding Common Stock of the Company plus issued and outstanding warrants calculated immediately following the Closing Date. The exercise price per share of Common Stock shall equal the fair market value of the Common Stock on the date of grant. The option shall vest over four years with Twenty-Five percent (25%) vesting at the first anniversary following the Commencement Date and then an additional Two and Eight Hundred Thirty-Three Ten Thousandths percent (2.0833%) vesting at the end of each month thereafter for a period of 36 months.

          4.4 Annual Equity Awards . During the Term, the Employee shall be eligible to receive awards under the equity-based incentive compensation plans adopted by the Company for which senior executives are generally eligible. The specific amount, terms and conditions of any such award, if any, shall be determined in the sole discretion of the Company, but with an annual target numbering between Twenty Hundredth percent (0.2%) and Thirty Hundredth percent (0.3%) of the Common Stock of the Company plus issued and outstanding warrants calculated at the time of the award.

          4.5 Fringe Benefits . The Employee shall be entitled to participate in the following programs and receive the following benefits (collectively, the “ Benefits ”) in accordance with the following provisions.

               (a) The Employee shall be entitled to participate in any retirement, health or dental programs generally made available to executive employees of the Company.

               (b) The Employee shall be entitled to participate in all vacation, life and disability insurance and other fringe benefit programs of the Company to the extent and on the same terms and conditions as are accorded to other executive employees of the Company.

          4.6 Reimbursement of Expenses . During the Term, the Employee shall be reimbursed for items of travel, food and lodging and miscellaneous expenses reasonably incurred by him/her on behalf of the Company, provided that such expenses are incurred, documented and submitted to the Company, all in accordance with the reimbursement policies of the Company as in effect from time to time. For purposes of satisfying Section 409A of the Internal Revenue Code of 1986, as amended (the “Code”), the parties agree that the amounts reimbursed under this Section 4.6 for one calendar year shall not affect the amounts reimbursed for other calendar years, and reimbursement payments, if any, shall in all events be made no later than the 15th day of the third month of the calendar year following the calendar year in which the applicable expense is incurred.

     5.  Confidentiality . The Employee recognizes and acknowledges that the Proprietary Information (as hereinafter defined) is a valuable, special and unique asset of the Company. As a result, both during the Term and thereafter, the Employee shall not, without the prior written consent of the Company, for any reason either directly or indirectly divulge to any third-party or use for his/her own benefit, or for any purpose other than the exclusive benefit of the Company, any confidential, proprietary, business and technical information or trade secrets of the Company or of any subsidiary or affiliate of the Company (the “ Proprietary Information ”) revealed, obtained or developed in the course of his/her employment with the Company.

Proprietary Information shall include any confidential or proprietary information or trade secrets relating to any patents or other intellectual property assigned by the Employee to the Company. Proprietary Information also shall include, but shall not be limited to the intangible personal property described in Section 6.2(b) hereof and, in addition, technical information, including research design, results, techniques and processes; apparatus and equipment design; computer software; technical management information, including project proposals, research plans, status reports, performance objectives and criteria, and analyses of areas for business development; and business information, including project, financial, accounting and personnel information, business strategies, plans and forecasts, customer lists, customer information and sales and marketing plans, efforts, information and data. In addition, “ Proprietary Information ” shall include all information and materials received by the Company or Employee from a third party subject to an obligation of confidentiality and/or non-disclosure. Nothing contained herein shall restrict the Employee’s ability to make such disclosures during the course of his/her employment as may be necessary or appropriate to the effective and efficient discharge of the duties required by or appropriate for the Position or as such disclosures may be required by law. Furthermore, nothing contained herein shall restrict the Employee from divulging or using for his/her own benefit or for any other purpose any Proprietary Information that is readily available to the general public so long as such information did not become available to the general public as a direct or indirect result of the Employee’s breach of this Section 5. Failure by the Company to mark any of the Proprietary Information as confidential or proprietary shall not affect its status as Proprietary Information under the terms of this Agreement.

     6.  Property .

          6.1 Removal and Distribution . All right, title and interest in and to Proprietary Information shall be and remain the sole and exclusive property of the Company. During the Term, the Employee shall not remove from the Company’s offices or premises any documents, records, notebooks, files, correspondence, reports, memoranda or similar materials of or containing Proprietary Information, or other materials or property of any kind belonging to the Company, unless necessary or appropriate in accordance with the duties and responsibilities required by or appropriate for the Position and, in the event that such materials or property are removed, all of the foregoing shall be returned to their proper files or places of safekeeping as promptly as possible after the removal shall serve its specific purpose. The Employee shall not make, retain, remove and/or distribute any copies of any of the foregoing for any reason whatsoever, except as may be necessary in the discharge of the assigned duties and shall not divulge to any third person the nature of and/or contents of any of the foregoing or of any other oral or written information to which he may have access or with which for any reason he may become familiar, except as disclosure shall be necessary in the performance of the duties; and upon the termination of his/her employment with the Company, the Employee shall return to the Company all originals and copies of the foregoing then in his/her possession or under his/her control, whether prepared by the Employee or by others.

          6.2 Developments .

               (a) The Employee acknowledges that all right, title and interest in and to any and all writings, documents, inventions, discoveries, ideas, developments, information, computer programs or instructions (whether in source code, object code, or any

other form), algorithms, formulae, plans, memoranda, tests, research, designs, innovations, systems, analyses, specifications, models, data, diagrams, flow charts, and/or techniques (whether patentable or non-patentable or whether reduced to written or electronic form or otherwise) that the Employee creates, makes, conceives, discovers or develops, either solely or jointly with any other person, at any time during the Term, whether during working hours or at the Company’s facility or at any other time or location, and whether upon the request or suggestion of the Company or otherwise, (collectively, “ Intellectual Work Product ”) shall be the sole and exclusive property of the Company. The Employee shall promptly disclose to the Company all Intellectual Work Product, and the Employee shall have no claim for additional compensation for the Intellectual Work Product, except for any excluded Intellectual Work Product that is wholly unrelated to the pharmaceutical industry, in the broadest sense, provided that such Intellectual Work Product is not conceived, discovered or developed, either solely or jointly with any other person during working hours or at the Company’s facility or using any other Company resource.

               (b) The Employee acknowledges that all the Intellectual Work Product that is copyrightable shall be considered a work made for hire under United States Copyright Law. To the extent that any copyrightable Intellectual Work Product may not be considered a work made for hire under the applicable provisions of the United States Copyright Law, or to the extent that, notwithstanding the foregoing provisions, the Employee may retain an interest in any Intellectual Work Product, the Employee hereby irrevocably assigns and transfers to the Company any and all right, title, or interest that the Employee may have in the Intellectual Work Product under copyright, patent, trade secret and trademark law, in perpetuity or for the longest period otherwise permitted by law, without the necessity of further consideration. The Company shall be entitled to obtain and hold in its own name all copyrights, patents, trade secrets, and trademarks with respect thereto.

               (c) The Employee shall reveal promptly all information relating to any such Intellectual Property to the Board of Directors, and, at the Company’s expense, shall cooperate with the Company and execute such documents as may be necessary or appropriate (i) in the event that the Company desires to seek copyright, patent or trademark protection, or other analogous protection, thereafter relating to the Intellectual Work Product, and when such protection is obtained, renew and restore the same, or (ii) to defend any opposition proceedings in respect of obtaining and maintaining such copyright, patent or trademark protection, or other analogous protection.

               (d) In the event the Company is unable after reasonable effort to secure the Employee’s signature on any of the documents referenced in Section 6.2 (c) hereof, whether because of the Employee’s physical or mental incapacity or for any other reason whatsoever, the Employee hereby irrevocably designates and appoints the Company and its duly authorized officers and agents as the Employee’s agent and attorney-in-fact, to act for and on the behalf and stead to execute and file any such documents and to do all other lawfully permitted acts to further the prosecution and issuance of any such copyright, patent or trademark protection, or other analogous protection, with the same legal force and effect as if executed by the Employee.

               (e) The Employee represents that the innovations, designs, systems, analyses, ideas, and all copyrights, patents, trademarks and trade names, or similar intangible personal property (collectively, the “ Pre-existing Property ”) identified on Schedule I hereof comprise all of the innovations, designs, systems, analyses, ideas and all copyrights, patents, trademarks and trade names, or similar intangible personal property that the Employee has made or conceived of prior to the date hereof, and same are excluded from the operation of the other provisions of this Section 6.2. In the event that the Employee learns of any Pre-existing Property that he inadvertently failed to include in Schedule I, and the circumstances surrounding the failure of such inclusion are reasonably satisfactory to the Company, the Employee and the Company shall jointly amend Schedule I to include such property.

     7.  Covenant not to Compete .

          7.1 Restrictions . Provided that the Company is in compliance with Section 8.7 hereof, if applicable, the Employee shall not, during the Term and for a period of one (1) year thereafter (the “ Restricted Period ”), except as an employee of the Company and in order to carry out the Employee’s duties hereunder, do any of the following directly or indirectly without the prior written consent of the Company in its sole discretion:

               (a) engage or participate, directly or indirectly, in any business activity competitive with the Business or the business of the Company or any of the Company’s subsidiaries or affiliates as conducted during the Term;

               (b) become interested (as owner, stockholder, lender, partner, co-venturer, director, officer, employee, agent, consultant or