ARDELYX, INC. 2008 STOCK INCENTIVE PLAN NOTICE OF RESTRICTED STOCK PURCHASE AWARD

Exhibit 10.5C

ARDELYX, INC. 2008 STOCK INCENTIVE PLAN

NOTICE OF RESTRICTED STOCK PURCHASE AWARD

You (the “Grantee”) have been granted the right to purchase shares of Common Stock of the Company, subject to the terms and conditions of this Notice of Restricted Stock Purchase Award (the “Notice”), the Ardelyx, Inc. 2008 Stock Incentive Plan, as amended from time to time (the “Plan”) and the Restricted Stock Purchase Award Agreement (the “Agreement”) attached hereto, as follows. Unless otherwise defined herein, the terms defined in the Plan shall have the same defined meanings in this Notice.

Vesting Schedule:

Subject to the Grantee’s Continuous Service and other limitations set forth in this Notice, the Agreement and the Plan, the Shares will “vest” in accordance with the following schedule:

25% of the Total Number of Shares of Common Stock Awarded shall vest on the first anniversary of the Vesting Commencement Date, and 1/48 of the Total Number of Shares of Common Stock Awarded shall vest on each monthly anniversary of the Vesting Commencement Date thereafter.

During any authorized leave of absence, the vesting of the Shares shall be suspended after the leave of absence exceeds a period of three (3) months. Vesting of the Shares shall resume upon the Grantee’s termination of the leave of absence and return to Continuous Service. The Vesting Schedule of the Shares shall be extended by the length of the suspension.

In the event of the Grantee’s change in status from Employee, Director or Consultant to any other status of Employee, Director or Consultant, the Shares shall continue to vest in accordance with the Vesting Schedule.

Vesting shall cease upon the date of termination of the Grantee’s Continuous Service for any reason, including death or Disability. For purposes of this Notice and the Agreement, the term “vest” shall mean, with respect to any Shares, that such Shares are no longer subject to

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repurchase at the Purchase Price per Share; provided, however, that such Shares shall remain subject to other restrictions on transfer set forth in the Agreement or the Plan. Shares that have not vested are deemed “Restricted Shares.” If the Grantee would become vested in a fraction of a Restricted Share, such Restricted Share shall not vest until the Grantee becomes vested in the entire Share. Notwithstanding the foregoing, the Shares subject to this Notice will be subject to the provisions of the Agreement and Section 11 of the Plan relating to the release of repurchase and forfeiture provisions in the event of a Corporate Transaction or Change of Control.

IN WITNESS WHEREOF, the Company and the Grantee have executed this Notice and agree that the Award is to be governed by the terms and conditions of this Notice, the Plan, and the Agreement.

THE GRANTEE ACKNOWLEDGES AND AGREES THAT THE SHARES SHALL VEST, IF AT ALL, ONLY DURING THE PERIOD OF THE GRANTEE’S CONTINUOUS SERVICE (NOT THROUGH THE ACT OF BEING HIRED, BEING GRANTED THIS AWARD OR ACQUIRING SHARES HEREUNDER). THE GRANTEE FURTHER ACKNOWLEDGES AND AGREES THAT NOTHING IN THIS NOTICE, THE AGREEMENT, NOR IN THE PLAN, SHALL CONFER UPON THE GRANTEE ANY RIGHT WITH RESPECT TO CONTINUATION OF THE GRANTEE’S CONTINUOUS SERVICE, NOR SHALL IT INTERFERE IN ANY WAY WITH THE GRANTEE’S RIGHT OR THE COMPANY’S RIGHT TO TERMINATE THE GRANTEE’S CONTINUOUS SERVICE AT ANY TIME, WITH OR WITHOUT CAUSE, AND WITH OR WITHOUT NOTICE. THE GRANTEE ACKNOWLEDGES THAT UNLESS THE GRANTEE HAS A WRITTEN EMPLOYMENT AGREEMENT WITH THE COMPANY TO THE CONTRARY, THE GRANTEE’S STATUS IS AT WILL.

The Grantee acknowledges receipt of a copy of the Plan and the Agreement and represents that he or she is familiar with the terms and provisions thereof, and hereby accepts the Award subject to all of the terms and provisions hereof and thereof. The Grantee has reviewed this Notice, the Agreement and the Plan in their entirety, has had an opportunity to obtain the advice of counsel prior to executing this Notice and fully understands all provisions of this Notice, the Agreement and the Plan. The Grantee hereby agrees that all questions of interpretation and administration relating to this Notice, the Plan and the Agreement shall be resolved by the Administrator in accordance with Section 17 of the Agreement. The Grantee further agrees to the venue selection in accordance with Section 18 of the Agreement. The Grantee further agrees to notify the Company upon any change in the residence address indicated in this Notice.

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Award Number:                    

ARDELYX, INC. 2008 STOCK INCENTIVE PLAN

RESTRICTED STOCK PURCHASE AWARD AGREEMENT

1. Purchase of Shares. Ardelyx, Inc., a Delaware corporation (the “Company”), hereby issues and sells to the Grantee (the “Grantee”) named in the Notice of Restricted Stock Purchase Award (the “Notice”), the Total Number of Shares of Common Stock Awarded set forth in the Notice (the “Shares”) for a Purchase Price per Share set forth in the Notice (the “Total Purchase Price”), subject to the Notice, this Restricted Stock Purchase Award Agreement (the “Agreement”) and the terms and provisions of the Company’s 2008 Stock Incentive Plan, as amended from time to time (the “Plan”), which is incorporated herein by reference. Payment for the Shares in the amount of the Total Purchase Price set forth in the Notice shall be made to the Company upon execution of the Notice. Unless otherwise defined herein, the terms defined in the Plan shall have the same defined meanings in this Agreement. All Shares sold hereunder will be deemed issued to the Grantee as fully paid and nonassessable shares, and the Grantee will have the right to vote the Shares at meetings of the Company’s shareholders. The Company shall pay any applicable stock transfer taxes imposed upon the issuance of the Shares to the Grantee hereunder.

2. Method of Payment. Payment of the Total Purchase Price shall be by any of the following, or a combination thereof, at the election of the Grantee; provided, however, that such payment method does not then violate an Applicable Law and, provided further, that the portion of the Total Purchase Price equal to the par value of the Shares must be paid in cash or other legal consideration permitted by the Delaware General Corporation Law:

(a) cash; or

(b) check.

3. Transfer Restrictions. The Shares sold to the Grantee hereunder may not be sold, transferred by gift, pledged, hypothecated, or otherwise transferred or disposed of by the Grantee prior to the date when the Shares become vested pursuant to the Vesting Schedule set forth in the Notice. Any attempt to transfer Restricted Shares in violation of this Section 3 will be null and void and will be disregarded. After the Shares vest, the Shares will be subject to the Company’s Right of First Refusal as set forth in Section 8 below.

4. Escrow of Stock. For purposes of facilitating the enforcement of the provisions of this Agreement, the Grantee agrees, immediately upon receipt of the certificate(s) for the Restricted Shares, to deliver such certificate(s), together with an Assignment Separate from Certificate in the form attached hereto as Exhibit A, executed in blank by the Grantee with respect to each such stock certificate, to the Secretary or Assistant Secretary of the Company, or their designee, to hold in escrow for so long as such Restricted Shares have not vested pursuant to the Vesting Schedule set forth in the Notice or continue to remain subject to the Company’s

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Right of First Refusal or Repurchase Right, with the authority to take all such actions and to effectuate all such transfers and/or releases as may be necessary or appropriate to accomplish the objectives of this Agreement in accordance with the terms hereof. The Grantee hereby acknowledges that the appointment of the Secretary or Assistant Secretary of the Company (or their designee) as the escrow holder hereunder with the stated authorities is a material inducement to the Company to make this Agreement and that such appointment is coupled with an interest and is accordingly irrevocable. The Grantee agrees that the Restricted Shares may be held electronically in a book entry system maintained by the Company’s transfer agent or other third-party and that all the terms and conditions of this Section 4 applicable to certificated Restricted Shares will apply with the same force and effect to such electronic method for holding the Restricted Shares. The Grantee agrees that such escrow holder shall not be liable to any party hereto (or to any other party) for any actions or omissions unless such escrow holder is grossly negligent relative thereto. The escrow holder may rely upon any letter, notice or other document executed by any signature purported to be genuine and may resign at any time. Upon the vesting of all Restricted Shares and termination of the Company’s Right of First Refusal and Repurchase Right, the escrow holder will, without further order or instruction, transmit to the Grantee the certificate evidencing such Shares, subject, however, to satisfaction of any withholding obligations provided in Section 6 below.

5. Distributions. Except as set forth in Section 9(e), the Company shall disburse to the Grantee all regular cash dividends with respect to the Shares and Additional Securities (whether vested or not), less any applicable withholding obligations.

6. Section 83(b) Election and Withholding of Taxes. The Grantee shall provide the Administrator with a copy of any timely election made pursuant to Section 83(b) of the Internal Revenue Code or similar provision of state law (collectively, an “83(b) Election”), a form of which is attached hereto as Exhibit B. If the Grantee makes a timely 83(b) Election, the Grantee shall immediately pay the Company the amount necessary to satisfy any applicable foreign, federal, state, and local income and employment tax withholding obligations. If the Grantee does not make a timely 83(b) Election, the Grantee shall, as Restricted Shares shall vest or at the time withholding is otherwise required by any Applicable Law, pay the Company the amount necessary to satisfy any applicable foreign, federal, state, and local income and employment tax withholding obligations. The Grantee hereby represents that he or she understands (a) the contents and requirements of the 83(b) Election, (b) the application of Section 83(b) to the receipt of the Shares by the Grantee pursuant to this Agreement, (c) the nature of the election to be made by the Grantee under Section 83(b), and (d) the effect and requirements of the 83(b) Election under relevant state and local tax laws. The Grantee further represents that he or she intends to file an election pursuant to Section 83(b) with the Internal Revenue Service within thirty (30) days following the date of this Agreement, and submit a copy of such election to the Company and with his or her federal tax return for the calendar year in which the date of this Agreement falls.

7. Additional Securities. Any securities or cash received (other than a regular cash dividend) as the result of ownership of the Restricted Shares (the “Additional Securities”), including, but not by way of limitation, warrants, options and securities received as a stock dividend or stock split, or as a result of a recapitalization or reorganization or other similar change in the Company’s capital structure, shall be retained in escrow in the same manner and

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subject to the same conditions and restrictions as the Restricted Shares with respect to which they were issued, including, without limitation, the Vesting Schedule set forth in the Notice, the Right of First Refusal and the Repurchase Right. The Grantee shall be entitled to direct the Company to exercise any warrant or option received as Additional Securities upon supplying the funds necessary to do so, in which event the securities so purchased shall constitute Additional Securities, but the Grantee may not direct the Company to sell any such warrant or option. If Additional Securities consist of a convertible security, the Grantee may exercise any conversion right, and any securities so acquired shall constitute Additional Securities. Appropriate adjustments to reflect the distribution of Additional Securities shall be made to the price per share to be paid upon the exercise of the Repurchase Right in order to reflect the effect of any such transaction upon the Company’s capital structure. In the event of any change in certificates evidencing the Shares or the Additional Securities by reason of any recapitalization, reorganization or other transaction that results in the creation of Additional Securities, the escrow holder is authorized to deliver to the issuer the certificates evidencing the Shares or the Additional Securities in exchange for the certificates of the replacement securities.

8. Company’s Right of First Refusal. The Grantee acknowledges and agrees that the Shares are subject to a right of first refusal (“Right of First Refusal”) as set forth in Article 10 of the Bylaws of the Company, which Right of First Refusal is incorporated herein by reference irrespective of whether the Bylaws are amended at some future date to remove the Right of First Refusal therefrom, and that, except in compliance with such Right of First Refusal, neither the Grantee nor a transferee (either being sometimes referred to herein as the “Holder”) shall sell, hypothecate, encumber or otherwise transfer any Shares or any right or interest therein.

9. Company’s Repurchase Right.

(a) Grant of Repurchase Right. The Company is hereby granted the right (the “Repurchase Right”), exercisable at any time during the six (6) month period (the “Share Repurchase Period”) following the date the Grantee’s Continuous Service terminates for any reason, with or without cause (including death or disability) (the “Termination Date”) to repurchase all or any portion of the Restricted Shares.

(b) Exercise of the Repurchase Right. The Repurchase Right shall be exercisable by written notice delivered to each Holder of the Shares prior to the expiration of the Share Repurchase Period. The notice shall indicate the number of Shares to be repurchased and the date on which the repurchase is to be effected, such date to be not later than the last day of the Share Repurchase Period. On the date on which the repurchase is to be effected, the Company and/or its assigns shall pay to the Holder of the Shares in cash or cash equivalents (including the cancellation of any purchase-money indebtedness) for Restricted Shares being repurchased an amount equal to the Purchase Price per Share previously paid by the Grantee to the Company for such Shares. Upon such payment to the Holder of the Shares or into escrow for the benefit of the Holder of the Shares, the Company and/or its assigns shall become the legal and beneficial owner of the Shares being repurchased and all rights and interest thereon or related thereto, and the Company shall have the right to transfer to its own name or its assigns the number of Shares being repurchased, without further action by the Holder of the Shares.

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(c) Assignment. Whenever the Company shall have the right to purchase Shares under this Repurchase Right, the Company may designate and assign one or more employees, officers, directors or shareholders of the Company or other persons or organizations, to exercise all or a part of the Company’s Repurchase Right.

(d) Termination of the Repurchase Right. The Repurchase Right shall terminate with respect to any Shares for which it is not timely exercised.

(e) Additional Securities. In the event of any transaction described in Sections10 or 11 of the Plan, the Repurchase Right shall apply to the new, substituted or additional capital stock or other property (including cash paid other than as a regular cash dividend) received in exchange for the Shares in consummation of any such transaction and such stock or property shall be deemed Additional Securities for purposes of this Agreement, but only to the extent the Shares are at the time covered by such Repurchase Right. Appropriate adjustments shall be made to the price per share payable upon exercise of the Repurchase Right to reflect the effect of any such transaction.

10. Stop-Transfer Notices. In order to ensure compliance with the restrictions on transfer set forth in this Agreement, the Notice or the Plan, the Company may issue appropriate “stop transfer” instructions to its transfer agent, if any, and, if the Company transfers its own securities, it may make appropriate notations to the same effect in its own records.

11. Refusal to Transfer. The Company shall not be required (i) to transfer on its books any Shares that have been sold or otherwise transferred in violation of any of the provisions of this Agreement or (ii) to treat as owner of such Shares or to accord the right to vote or pay dividends to any purchaser or other transferee to whom such Shares shall have been so transferred.

12. Restrictive Legends. The Grantee understands and agrees that the Company shall cause the legends set forth below or legends substantially equivalent thereto, to be placed upon any certificate(s) evidencing ownership of the Shares together with any other legends that may be required by the Company or by state or federal securities laws:

THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933 (THE “ACT”) AND MAY NOT BE OFFERED, SOLD OR OTHERWISE TRANSFERRED, PLEDGED OR HYPOTHECATED UNLESS AND UNTIL REGISTERED UNDER THE ACT OR, IN THE OPINION OF COUNSEL SATISFACTORY TO THE ISSUER OF THESE SECURITIES, SUCH OFFER, SALE OR TRANSFER, PLEDGE OR HYPOTHECATION IS IN COMPLIANCE THEREWITH.

THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO CERTAIN RESTRICTIONS ON TRANSFER AND A REPURCHASE RIGHT HELD BY THE ISSUER OR ITS ASSIGNEE(S) AS SET FORTH IN THE RESTRICTED

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STOCK PURCHASE AGREEMENT BETWEEN THE ISSUER AND THE ORIGINAL HOLDER OF THESE SHARES, A COPY OF WHICH MAY BE OBTAINED AT THE PRINCIPAL OFFICE OF THE ISSUER. SUCH TRANSFER RESTRICTIONS AND REPURCHASE RIGHT ARE BINDING ON TRANSFEREES OF THESE SHARES.

THE SHARES REPRESENTED BY THIS CERTIFICATE ARE SUBJECT TO A RIGHT OF FIRST REFUSAL IN FAVOR OF THE COMPANY AS SET FORTH IN THE BYLAWS OF THE COMPANY

13. Lock-Up Agreement.

(a) Agreement. The Grantee, if requested by the Company and the lead underwriter of any public offering of the Common Stock (the “Lead Underwriter”), hereby irrevocably agrees not to sell, contract to sell, grant any option to purchase, transfer the economic risk of ownership in, make any short sale of, pledge or otherwise transfer or dispose of any interest in any Common Stock or any securities convertible into or exchangeable or exercisable for or any other rights to purchase or acquire Common Stock (except Common Stock included in such public offering or acquired on the public market after such offering) during the 180-day period following the effective date of a registration statement of the Company filed under the Securities Act of 1933, as amended, or such shorter or longer period of time as the Lead Underwriter shall specify. The Grantee further agrees to sign such documents as may be requested by the Lead Underwriter to effect the foregoing and agrees that the Company may impose stop-transfer instructions with respect to such Common Stock subject until the end of such period. The Company and the Grantee acknowledge that each Lead Underwriter of a public offering of the Company’s stock, during the period of such offering and for the lock-up period thereafter, is an intended beneficiary of this Section 13.

(b) No Amendment Without Consent of Underwriter. During the period from identification as a Lead Underwriter in connection with any public offering of the Company’s Common Stock until the earlier of (i) the expiration of the lock-up period specified in Section 13(a) in connection with such offering or (ii) the abandonment of such offering by the Company and the Lead Underwriter, the provisions of this Section 13 may not be amended or waived except with the consent of the Lead Underwriter.

14. Grantee’s Representations. In the event the Shares purchasable pursuant to this Agreement have not been registered under the Securities Act of 1933, as amended, at the time of purchase, the Grantee shall, if required by the Company, concurrently with the purchase of the Shares, deliver to the Company his or her Investment Representation Statement in the form attached hereto as Exhibit C.

15. Entire Agreement: Governing Law. The Notice, the Plan and this Agreement constitute the entire agreement of the parties with respect to the subject matter hereof and supersede in their entirety all prior undertakings and agreements of the Company and the Grantee with respect to the subject matter hereof, and may not be modified adversely to the Grantee’s

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interest except by means of a writing signed by the Company and the Grantee. These agreements are to be construed in accordance with and governed by the internal laws of the State of California without giving effect to any choice of law rule that would cause the application of the laws of any jurisdiction other than the internal laws of the State of California to the rights and duties of the parties. Should any provision of the Notice or this Agreement be determined to be illegal or unenforceable, the other provisions shall nevertheless remain effective and shall remain enforceable.

16. Construction. The captions used in the Notice and this Agreement are inserted for convenience and shall not be deemed a part of the Agreement for construction or interpretation. Except when otherwise indicated by the context, the singular shall include the plural and the plural shall include the singular. Use of the term “or” is not intended to be exclusive, unless the context clearly requires otherwise.

17. Administration and Interpretation. Any question or dispute regarding the administration or interpretation of the Notice, the Plan or this Agreement shall be submitted by the Grantee or by the Company to the Administrator. The resolution of such question or dispute by the Administrator shall be final and binding on all persons.

18. Venue. The Company, the Grantee, and the Grantee’s assignees pursuant to Section 3 (the “parties”) agree that any suit, action, or proceeding arising out of or relating to the Notice, the Plan or this Agreement shall be brought in the United States District Court for the Northern District of California (or should such court lack jurisdiction to hear such action, suit or proceeding, in a California state court in the County of Santa Clara) and that the parties shall submit to the jurisdiction of such court. The parties irrevocably waive, to the fullest extent permitted by law, any objection the party may have to the laying of venue for any such suit, action or proceeding brought in such court. If any one or more provisions of this Section 18 shall for any reason be held invalid or unenforceable, it is the specific intent of the parties that such provisions shall be modified to the minimum extent necessary to make it or its application valid and enforceable.

19. Notices. Any notice required or permitted hereunder shall be given in writing and shall be deemed effectively given upon personal delivery, upon deposit for delivery by an internationally recognized express mail courier service or upon deposit in the United States mail by certified mail (if the parties are within the United States), with postage and fees prepaid, addressed to the other party at its address as shown in these instruments, or to such other address as such party may designate in writing from time to time to the other party.

20. Spousal Consent. Grantee shall cause his or her spouse to execute a Consent of Spouse in the form attached hereto as Exhibit D concurrently with the execution of this Agreement or, if later, at the time Grantee becomes married.

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EXHIBIT A

STOCK ASSIGNMENT SEPARATE FROM CERTIFICATE

[Please sign this document but do not date it. The date and information of the transferee will be completed if and when the shares are assigned.]

FOR VALUE RECEIVED,                                          hereby sells, assigns and transfers unto                                         ,                      (            ) shares of the Common Stock of Ardelyx, Inc., a Delaware corporation (the “Company”), standing in his or her name on the books of, the Company represented by Certificate No.      herewith, and does hereby irrevocably constitute and appoint the Secretary of the Company attorney to transfer the said stock in the books of the Company with full power of substitution.

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EXHIBIT B

ELECTION UNDER SECTION 83(b)

OF THE INTERNAL REVENUE CODE OF 1986

The undersigned taxpayer hereby elects, pursuant to the Internal Revenue Code, to include in gross income for 20     the amount of any compensation taxable in connection with the taxpayer’s receipt of the property described below:

1. The name, address, taxpayer identification number and taxable year of the undersigned are:

TAXPAYER’S NAME:

TAXPAYER’S SOCIAL SECURITY NO.:

SPOUSE’S SOCIAL SECURITY NO.:

TAXABLE YEAR: Calendar Year 20    

ADDRESS:

2. The property which is the subject of this election is                  shares of common stock of Ardelyx, Inc.

3. The property was transferred to the undersigned on             , 20    .

4. The property is subject to the following restrictions: The property is subject to a repurchase right pursuant to which the issuer has the right to acquire the property at the original purchase price if for any reason taxpayer’s employment or service with the issuer is terminated. The issuer’s repurchase right lapses in a series of periodic installments.

5. The fair market value of the property at the time of transfer (determined without regard to any restriction other than a restriction which by its terms will never lapse) is: $         per share x                  shares = $        .

6. The undersigned paid $         per share x                  shares for the property transferred or a total of $        .

The undersigned has submitted a copy of this statement to the person for whom the services were performed in connection with the undersigned’s receipt of the above-described property. The undersigned taxpayer is the person performing the services in connection with the transfer of said property.

The undersigned will file this election with the Internal Revenue Service office to which he or she files his or her annual income tax return not later than 30 days after the date of transfer of the property. A copy of the election also will be furnished to the person for whom the services

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were performed. Additionally, the undersigned will include a copy of the election with his or her income tax return for the taxable year in which the property is transferred. The undersigned understands that this election will also be effective as an election under California law.

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EXHIBIT C

ARDELYX, INC. 2008 STOCK INCENTIVE PLAN

INVESTMENT REPRESENTATION STATEMENT

In connection with the purchase of the above-listed Securities, the undersigned Grantee represents to the Company the following:

(a) The Grantee is aware of the Company’s business affairs and financial condition and has acquired sufficient information about the Company to reach an informed and knowledgeable decision to acquire the Securities. The Grantee is acquiring these Securities for investment for the Grantee’s own account only and not with a view to, or for resale in connection with, any “distribution” thereof within the meaning of the Securities Act of 1933, as amended (the “Securities Act”).

(b) The Grantee acknowledges and understands that the Securities constitute “restricted securities” under the Securities Act and have not been registered under the Securities Act in reliance upon a specific exemption therefrom, which exemption depends upon among other things, the bona fide nature of the Grantee’s investment intent as expressed herein. In this connection, the Grantee understands that, in the view of the Securities and Exchange Commission, the statutory basis for such exemption may be unavailable if the Grantee’s representation was predicated solely upon a present intention to hold these Securities for the minimum capital gains period specified under tax statutes, for a deferred sale, for or until an increase or decrease in the market price of the Securities, or for a period of one year or any other fixed period in the future. The Grantee further understands that the Securities must be held indefinitely unless they are subsequently registered under the Securities Act or an exemption from such registration is available. The Grantee further acknowledges and understands that the Company is under no obligation to register the Securities. The Grantee understands that the certificate evidencing the Securities will be imprinted with a legend which prohibits the transfer of the Securities unless they are registered or such registration is not required in the opinion of counsel satisfactory to the Company.

(c) The Grantee is familiar with the provisions of Rule 701 and Rule 144, each promulgated under the Securities Act, which, in substance, permit limited public resale of “restricted securities” acquired, directly or indirectly from the issuer thereof, in a non-public offering subject to the satisfaction of certain conditions. Rule 701 provides that if the issuer

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qualifies under Rule 701 at the time of the sale of the Shares to the Grantee, the sale will be exempt from registration under the Securities Act. In the event the Company becomes subject to the reporting requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, ninety (90) days thereafter (or such longer period as any market stand-off agreement may require) the Securities exempt under Rule 701 may be resold, subject to the satisfaction of certain of the conditions specified by Rule 144, including: (1) the resale being made through a broker in an unsolicited “broker’s transaction” or in transactions directly with a market maker (as said term is defined under the Securities Exchange Act of 1934); and, in the case of an affiliate, (2) the availability of certain public information about the Company, (3) the amount of Securities being sold during any three month period not exceeding the limitations specified in Rule 144(e), and (4) the timely filing of a Form 144, if applicable.

In the event that the Company does not qualify under Rule 701 at the time of sale of the Securities, then the Securities may be resold in certain limited circumstances subject to the provisions of Rule 144, which requires the resale to occur not less than six (6) months after the later of the date the Securities were sold by the Company or the date the Securities were sold by an affiliate of the Company, within the meaning of Rule 144; and, in the case of acquisition of the Securities by an affiliate, or by a non-affiliate who subsequently holds the Securities less than one (1) year, the satisfaction of the conditions set forth in sections (1), (2), (3) and (4) of the paragraph immediately above.

(d) The Grantee further understands that in the event all of the applicable requirements of Rule 701 or 144 are not satisfied, registration under the Securities Act, compliance with Regulation A, or some other registration exemption will be required; and that, notwithstanding the fact that Rules 144 and 701 are not exclusive, the Staff of the Securities and Exchange Commission has expressed its opinion that persons proposing to sell private placement securities other than in a registered offering and otherwise than pursuant to Rules 144 or 701 will have a substantial burden of proof in establishing that an exemption from registration is available for such offers or sales, and that such persons and their respective brokers who participate in such transactions do so at their own risk. The Grantee understands that no assurances can be given that any such other registration exemption will be available in such event.

(e) The Grantee represents that the Grantee is a resident of the state of                                         .

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EXHIBIT D

CONSENT OF SPOUSE

I,                                         , spouse of                                         , have read and approved the foregoing Agreement. In consideration of the right of my spouse to purchase shares of Ardelyx, Inc. as set forth in the Agreement, I hereby appoint my spouse as my attorney-in-fact in respect to the exercise of any rights under the Agreement insofar as I may have any rights under the community property laws of the State of California or similar laws relating to marital property in effect in the state of our residence as of the date of the signing of the foregoing Agreement.

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