MASTER SERVICES AGREEMENT

Exhibit 10.13

MASTER SERVICES AGREEMENT

     THIS Master Services Agreement (the “Agreement”) is effective as of the 28 ^th day of October, 2004, (the “Effective Date”), by and between i3 Research, a division of Ingenix Pharmaceutical Services (UK) Limited. (“Ingenix”), with offices at Sygnus Court, 22-32 Market Street, Maidenhead, Berkshire, UK SL6 8AD, and Corcept Therapeutics Incorporated (“Sponsor”), with offices at 275 Middlefield Road, Suite A, Menlo Park, CA 94025.

     WHEREAS, Sponsor is engaged in research and development of pharmaceutical products; and

     WHEREAS, Ingenix is engaged in providing services to pharmaceutical manufacturers in support of their clinical research and product development activities;

     WHEREAS, Sponsor wishes to retain Ingenix, from time to time, to assist in certain product development activities relating to certain of Sponsor’s clinical studies (each of which shall be referred to as a “Study”); and

     WHEREAS, Sponsor agrees to compensate Ingenix for its services.

     NOW THEREFORE, in consideration of the premises and the mutual promises and undertakings herein contained, the parties agree as follows:

SECTION 1 — Services — General

1.1 Sponsor hereby retains Ingenix to provide the services (the “Services”) that are described in written task orders (“Task Orders”, a form of which is attached to this Agreement as Exhibit A) which are executed by the parties from time to time. The parties acknowledge and agree that their respective Affiliates may execute Task Orders under this Agreement. In that event, such Affiliate(s) shall be bound by all terms and conditions of this Agreement and the applicable Task Order, and entitled to all rights and protections afforded Sponsor or Ingenix under this Agreement. While this Agreement creates certain obligations between the parties, it does not create an obligation on the part of Sponsor or any Sponsor Affiliate to engage Ingenix to provide services, or an obligation on the part of Ingenix or any Ingenix Affiliate to provide services; such obligations shall arise only upon the execution of a Letter of Intent (a form of which is attached hereto as Exhibit B), a Task Order, or a written amendment to a Task Order (a “Change Order”, a form of which is attached hereto as Exhibit C). The terms of this Agreement shall be made a part of and incorporated by reference into each Task Order and each Task Order is incorporated and made a part of this Agreement. In the event of a conflict between the terms of this Agreement and a Task Order, the terms of this Agreement will govern, unless otherwise agreed in a Task Order.

1.2 “Affiliate” means, when associated with a party to this Agreement, any entity that controls, is controlled by or is under common control with, that party. “Control” means the possession, directly or indirectly, of at least 50% of the share capital or voting rights or of the power to direct or cause the direction of the management and policies of an entity, whether through the ownership of voting securities, by contract or otherwise.

1.3 Each Task Order shall constitute a unique agreement and shall stand alone with respect to any other Task Order entered into under this Agreement. To the extent required under Title 21 CFR Part 312.52 in the United States, and any equivalent laws of other countries, the parties shall document separately in writing the transfer by Sponsor to Ingenix of any of Sponsor’s responsibilities. In the absence of such a separate document, the description of Services provided in the relevant Task Order shall be deemed the required written transfer of obligations from Sponsor to i3 Research for that Study. Notwithstanding the foregoing, Sponsor will retain the ultimate authority and control over and

1

responsibility for each Study. Sponsor shall retain and have responsibility for all Study activities not specifically transferred to Ingenix. The parties acknowledge and agree that Sponsor shall at all times be deemed to be the “sponsor” of each study pursuant to the terms of the U. S. Federal Food, Drug and Cosmetic Act, as from time to time amended, the regulations of the U.S. Food and Drug Administration (“FDA”), as promulgated in the Title 21 of U.S. Code of Federal Regulations, and any equivalent laws of other countries.

1.4 The terms of a Task Order may be amended or modified by mutual written agreement of Ingenix and Sponsor. If Sponsor wishes (i) to change the timelines, deliverables or scope or scale of the Services covered by a Task Order, (ii) to obtain additional services not initially covered by a Task Order, or (iii) to reduce or remove any of the Services covered by a Task Order, Sponsor shall so advise Ingenix. If Ingenix believes a change in the scope or scale of Services is necessary or advisable, Ingenix shall so advise Sponsor. The parties will negotiate diligently and in good faith the proposed revisions to the timelines, deliverables, scope or scale of Services and the professional fees and costs for performing changed or additional services or for reducing or removing Services, and shall execute a Change Order to the applicable Task Order. In the event Ingenix provides additional services or expends resources, at Sponsor’s written request and in strict accordance with Sponsor’s requirements, in the absence of a Change Order, Sponsor will compensate and/or reimburse Ingenix for all fees and reasonable costs incurred.

1.5 The parties shall perform their obligations under this Agreement and each Task Order in accordance with the terms of this Agreement, the applicable Task Order, applicable provisions of the Study protocol, agreed upon Standard Operating Procedures; the current Guidelines for Good Clinical Practice (“GCP Guidelines”); the Declaration of Helsinki of the 41st World Medical Assembly, South Africa 1996 as amended; and applicable local laws and regulations.

1.6 Neither party shall have any obligation of exclusivity of any nature to the other, or any obligation to conduct, sponsor, or to offer to conduct or sponsor, any particular services or study or any number of studies, unless specified in a Task Order. Each party shall be free to provide services to or conduct or sponsor clinical or research studies involving other parties, so long as a party’s agreement with any such third party does not prevent it from performing its obligations under this Agreement or a Task Order. Each party understands and agrees that the other party or its Affiliates may be in a business similar to or offer products or services the same as the other party (or one or more of its Affiliates) and may already have developed, be in the process of developing, or plan to develop products, services and information similar to those owned or developed by the other. Nothing contained herein shall be construed to prohibit a party from so doing as long as it does so independently and without using Confidential Information disclosed by the other.

1.7 During the term of this Agreement Ingenix shall maintain all materials and all other data obtained or generated by Ingenix in the course of providing the Services, including all computerized records and files (“Work Product”), in a secure area reasonably protected from fire, theft and destruction. At the expiration or termination of this Agreement and each Task Order Sponsor shall provide Ingenix with written instructions as to the disposition of the Work Product obtained or generated by Ingenix in the course of providing the applicable Services. Such written instructions will provide that Ingenix (a) deliver the Work Product, in the form in which Ingenix currently holds them, to a designated Sponsor location or to such other entity or at such other address as Sponsor may specify, (b) retain the Work Product for the period of time specified in the Task Order, or (c) dispose of the Work Product, except for those portions which Ingenix is required by law or regulation to store or maintain. After termination of this Agreement or the applicable Task Order, storage, destruction, shipping and other services relating to the final record disposition will be billed as Pass — through Expenses (as defined below) to Sponsor. Notwithstanding the foregoing, Ingenix may retain copies of any of the Work Product as are reasonably necessary for regulatory or insurance purposes, subject to its ongoing obligation to maintain the confidentiality of such materials.

2

SECTION 2 — Institution/Investigator — Services

2.1 The parties acknowledge that Ingenix’ Services under a Task Order may include identifying potential medical institutions (“Institutions”) or clinical investigators (“Investigators”) and/or negotiating, executing and/or administering contracts with them governing their conduct of the Study (“Study Agreements”). If, pursuant to a Task Order, Sponsor delegates to Ingenix the responsibility for negotiating and/or executing Study Agreements, the following provisions will apply:

2.2 The parties acknowledge and agree that, for the purposes of this Agreement or any Task Order, Institutions/Investigators shall not be considered as employees, agents or subcontractors of Ingenix or of Sponsor and that Investigators will be required to exercise their own independent medical judgement. Ingenix’ responsibilities with respect to Institutions/Investigators shall be limited to those specifically set forth in the applicable Task Order.

SECTION 3 — Compensation and Expenses

3.1 As compensation for providing the Services, Sponsor shall pay Ingenix professional fees in the amounts and upon the terms specified in one or more attachments to the applicable Task Order. Each Task Order will include as attachments a study budget containing Ingenix’ estimated professional fees and Pass-through Expenses (“the Budget”), a payment schedule (the “Payment Schedule”) and a timeline showing performance milestones (the “Timeline”). If the assumptions under which the parties created the Budget, the Payment Schedule or the Timeline prove to be inaccurate, in whole or in part, or if matters reasonably beyond the control of the parties detrimentally affect a Study, then the parties shall review

3

each of the Budget, the Payment Schedule and the Timeline and incorporate reasonable revisions in a Change Order to the applicable Task Order.

3.2 Sponsor will reimburse Ingenix for reasonable travel and other reasonable out-of-pocket expenses incurred by Ingenix personnel identified in the Budget or at the request of Sponsor (“Pass-through Expenses”), unless Ingenix expressly agrees in advance to waive such reimbursement. Pass-through Expenses shall include the following:

Ingenix shall submit a reasonably detailed invoice with copies of receipts attached of such expenses to Sponsor on a monthly basis.

3.3 Professional fees and estimated Pass-through Expenses, as indicated in the applicable Budget, shall be exclusive of value added tax (“VAT”), except where VAT is irrecoverable by Ingenix.

3.4 All invoices and payments will be stated and made in Euros unless otherwise provided for in the applicable Task Order. If Ingenix performs Services whereby it incurs costs or expenses in a currency different than Euros or another currency specified in a Task Order, Ingenix shall have the option of invoicing Sponsor for such costs and expenses in Euros after applying the applicable exchange spot rate published in the Financial Times on the last business day of the relevant invoice period to the initial currency. Sponsor will pay each invoice, via check or wire transfer of immediately available funds, within 30 days of receipt of the invoice.

3.5 In the event Sponsor disputes one or more items in an invoice, Sponsor will notify Ingenix in writing within fifteen (15) business days of receipt of the invoice and such notice shall contain a reasonably specific description of the item(s) being disputed and the basis therefor. Ingenix will respond to Sponsor within fifteen (15) business days of receipt of the notification. This written communication pattern will continue until Ingenix has provided Sponsor with sufficient justification for the disputed item(s) or until the parties agree to a resolution of the disputed amount. Sponsor shall pay the undisputed portion of the invoice within thirty (30) days of receipt of the invoice and shall use commercially reasonable best efforts to pay the disputed amount within fifteen (15) days of resolution of the dispute. In the event the parties are unable to reach a satisfactory resolution within one hundred eighty (180) days of the original invoice, either party can submit the dispute to binding arbitration in accordance with Section 9.2 of this Agreement.

SECTION 4 — Confidentiality

4.1 Each party acknowledges that in connection with the performance of the Services, it may receive, learn or have access to confidential, trade secret, or proprietary information concerning the other party or third parties to whom the other party has an obligation of confidentiality (“Confidential Information”).

4

4.2 Sponsor’s Confidential Information shall include, without limitation, information regarding the Sponsor’s business; drug products and proposed drug products; current or proposed studies on Sponsor’s products; prior research and results of studies on Sponsor’s drug products; and reports and decisions resulting from clinical trials on Sponsor’s drug products. Ingenix Confidential Information shall include, without limitation, business information; information regarding Ingenix services and documentation; Ingenix’ business methodologies and processes and associated algorithms, tools, programs, software architecture, including but not limited to source codes, and technology.

4.3 Each party agrees that (a) it will use the other party’s Confidential Information only as may be necessary in connection with the Services; (b) it will treat such information as confidential and proprietary; (c) without the prior written consent of the other party it will not disclose such information orally or in writing to any third party (except however, to disclose such information to its respective agents or representatives, IRB/Ethics Committee members, or the FDA or other regulatory authorities, all of whom have a need to know such information in connection with the purpose for which it is disclosed to the party); (d) it will take all reasonable precautions to protect the Confidential Information; and (e) it will not otherwise appropriate such information to its own use or to the use of any other person or entity. Without limiting the foregoing, each party agrees to take at least such precautions to protect the other party’s Confidential Information as it takes to protect its own Confidential Information. Upon termination of this Agreement, each party will return to the other party or certify as destroyed all tangible items containing any of the other party’s Confidential Information that are held by that party or its employees, agents or contractors. However, each party may retain archive copies of information as required by applicable regulatory requirements. Each party agrees to notify the other party if it becomes aware of any unauthorized use or disclosure of the other party’s Confidential Information.

4.4 If either party believes it is required by law or by a subpoena or court order to disclose any of the other party’s Confidential Information, it shall promptly notify the other party prior to any disclosure and shall make all reasonable efforts to allow the other party an opportunity to seek a protective order or other judicial relief.

4.5 Nothing in this Agreement shall be construed to restrict disclosure or use of information that (a) was in the possession of or rightfully known by the recipient, without an obligation to maintain its confidentiality, prior to receipt from the other party; (b) is or becomes generally known to the public without violation of this Agreement; (c) is obtained by the recipient in good faith from a third party having the right to disclose it without an obligation of confidentiality; (d) is independently developed by the receiving party without reference to the other party’s Confidential Information; or (e) is required by law to be disclosed.

4.6 Each party agrees not to disclose or utilize individual patient or medical claim information in any way that would violate any physician-patient confidence or any state or federal laws or regulations.

4.7 Except as required by law neither party shall disclose Sponsor’s retention of Ingenix for professional services or the terms of this Agreement or any Task Order, unless each party has agre