INVESTOR RIGHTS AGREEMENT

This Investor Rights Agreement (this “ Agreement ”) is made and entered into as of December 6, 2006 among Access Pharmaceuticals, Inc., a Delaware corporation (the “ Company ”), and each of the purchasers executing this Agreement and listed on Schedule 1 attached hereto (collectively, the “ Purchasers ”).

This Agreement is being entered into pursuant to the Convertible Note and Warrant Purchase Agreement, dated as of the date hereof, by and among the Company and the Purchasers (the “ Purchase Agreement ”).

The Company and the Purchasers hereby agree as follows:

1.   Definitions .

Capitalized terms used and not otherwise defined herein shall have the meanings given such terms in the Purchase Agreement. As used in this Agreement, the following terms shall have the following meanings:

“ Advice ” shall have the meaning set forth in Section 3(m).

“ Affiliate ” means, with respect to any Person, any other Person that directly or indirectly controls or is controlled by or under common control with such Person. For the purposes of this definition, “control,” when used with respect to any Person, means the possession, direct or indirect, of the power to direct or cause the direction of the management and policies of such Person, whether through the ownership of voting securities, by contract or otherwise; and the terms of “affiliated,” “controlling” and “controlled” have meanings correlative to the foregoing.

“ Blackout Period ” shall have the meaning set forth in Section 3(n).

“ Board ” shall have the meaning set forth in Section 3(n).

“ Business Day ” means any day except Saturday, Sunday and any day which shall be a legal holiday or a day on which banking institutions in the State of Texas generally are authorized or required by law or other government actions to close.

“ Commission ” means the Securities and Exchange Commission.

“ Common Stock ” means the Company’s Common Stock, par value $0.01 per share.

“ Conversion Shares ” means the shares of Common Stock issuable upon conversion of the Notes purchased by the Purchasers pursuant to the Purchase Agreement, including, without limitation, shares of Common Stock issued in payment of interest due on such Notes.

“ Effectiveness Period ” shall have the meaning set forth in Section 2.

“ Event ” shall have the meaning set forth in Section 7(e).

“ Exchange Act ” means the Securities Exchange Act of 1934, as amended.

“ Holder ” or “ Holders ” means the holder or holders, as the case may be, from time to time of Registrable Securities, including without limitation the Purchasers and their assignees.

“ Indemnified Party ” shall have the meaning set forth in Section 5(c).

“ Indemnifying Party ” shall have the meaning set forth in Section 5(c).

“ Losses ” shall have the meaning set forth in Section 5(a).

“ Notes ” means the Secured Convertible Promissory Notes issued to the Purchasers pursuant to the Purchase Agreement.

“ Person ” means an individual or a corporation, partnership, trust, incorporated or unincorporated association, joint venture, limited liability company, joint stock company, government (or an agency or political subdivision thereof) or other entity of any kind.

“ Proceeding ” means an action, claim, suit, investigation or proceeding (including, without limitation, an investigation or partial proceeding, such as a deposition), whether commenced or threatened.

“ Prospectus ” means the prospectus included in any Registration Statement (including, without limitation, a prospectus that includes any information previously omitted from a prospectus filed as part of an effective registration statement in reliance upon Rule 430A promulgated under the Securities Act), as amended or supplemented by any prospectus supplement, with respect to the terms of the offering of any portion of the Registrable Securities covered by such Registration Statement, and all other amendments and supplements to the Prospectus, including post-effective amendments, and all material incorporated by reference in such Prospectus.

“ Qualified Financing ” means the next equity financing (including an offering of convertible debt securities) of the Company in connection with which SCO Securities LLC serves as placement agent.

“ Registrable Securities ” means (a) the Conversion Shares and the Warrant Shares (without regard to any limitations on beneficial ownership contained in the Note or the Warrants) or other securities issued or issuable to each Purchaser or its transferee or designee (i) upon conversion of the Notes and/or upon exercise of the Warrants, or (ii) upon any dividend or distribution with respect to, any exchange for or any replacement of such Notes, Conversion Shares, Warrants or Warrant Shares or (iii) upon any conversion, exercise or

exchange of any securities issued in connection with any such distribution, exchange or replacement; (b) securities issued or issuable upon any stock split, stock dividend, recapitalization or similar event with respect to the foregoing; and (c) any other security issued as a dividend or other distribution with respect to, in exchange for, in replacement or redemption of, or in reduction of the liquidation value of, any of the securities referred to in the preceding clauses; provided, however, that such securities shall cease to be Registrable Securities when such securities have been sold to or through a broker or dealer or underwriter in a public distribution or a public securities transaction or when such securities may be sold without any restriction pursuant to Rule 144(k) as determined by the counsel to the Company pursuant to a written opinion letter, addressed to the Company’s transfer agent to such effect as described in Section 2 of this Agreement.

“ Registration Statement ” means the registration statements and any additional registration statements contemplated by Section 2, including (in each case) the Prospectus, amendments and supplements to such registration statement or Prospectus, including pre- and post-effective amendments, all exhibits thereto, and all material incorporated by reference in such registration statement.

“ Rule 144 ” means Rule 144 promulgated by the Commission pursuant to the Securities Act, as such Rule may be amended from time to time, or any similar rule or regulation hereafter adopted by the Commission having substantially the same effect as such Rule.

“ Rule 158 ” means Rule 158 promulgated by the Commission pursuant to the Securities Act, as such Rule may be amended from time to time, or any similar rule or regulation hereafter adopted by the Commission having substantially the same effect as such Rule.

“ Rule 415 ” means Rule 415 promulgated by the Commission pursuant to the Securities Act, as such Rule may be amended from time to time, or any similar rule or regulation hereafter adopted by the Commission having substantially the same effect as such Rule.

“ Securities Act ” means the Securities Act of 1933, as amended.

“ Special Counsel ” means Wiggin and Dana LLP.

“ Warrants ” means the Common Stock purchase warrants issued pursuant to the Purchase Agreement, including, without limitation the Placement Agent Warrants.

“ Warrant Shares ” means the shares of Common Stock issuable upon the exercise of the Warrants (including, without limitation, the Placement Agent Warrants) issued or to be issued to the Purchasers or their assignees or designees in connection with the offering consummated under the Purchase Agreement.

2.   Registration . As soon as possible following the Closing Date (but not later than the Filing Date), the Company shall prepare and file with the Commission a “shelf” Registration Statement covering all Registrable Securities for a secondary or resale offering

to be made on a continuous basis pursuant to Rule 415. The Registration Statement shall be on Form S-3 (or if such form is not available to the Company on another form appropriate for such registration in accordance herewith). The Company shall use its reasonable best efforts to cause the Registration Statement to be declared effective under the Securities Act not later than sixty (60) days after the Filing Date (including filing with the Commission a request for acceleration of effectiveness in accordance with Rule 461 promulgated under the Securities Act within five (5) Business Days of the date that the Company is notified (orally or in writing, whichever is earlier) by the Commission that a Registration Statement will not be “reviewed,” or not be subject to further review) and to keep such Registration Statement continuously effective under the Securities Act until such date as is the earlier of (x) the date when all Registrable Securities covered by such Registration Statement have been sold or (y) with respect to such Holder, such time as all Registrable Securities held by such Holder may be sold without any restriction pursuant to Rule 144(k) as determined by the counsel to the Company pursuant to a written opinion letter, addressed to the Company’s transfer agent to such effect (the “ Effectiveness Period ”). For purposes of the obligations of the Company under this Agreement, no Registration Statement shall be considered “effective” with respect to any Registrable Securities unless such Registration Statement lists the Holders of such Registrable Securities as “Selling Stockholders” and includes such other information as is required to be disclosed with respect to such Holders to permit them to sell their Registrable Securities pursuant to such Registration Statement, unless any such Holder is not included as a “Selling Stockholder” pursuant to Section 3(m). Such Registration Statement also shall cover, to the extent allowable under the Securities Act and the Rules promulgated thereunder (including Securities Act Rule 416), such indeterminate number of additional shares of Common Stock resulting from stock splits, stock dividends or similar transactions with respect to the Registrable Securities.

3.   Registration Procedures .

In connection with the Company’s registration obligations hereunder, the Company shall:

(a) Prepare and file with the Commission on or prior to the Filing Date, a Registration Statement on Form S-3 (or if such form is not available to the Company on another form appropriate for such registration in accordance herewith) (which shall include a Plan of Distribution substantially in the form of Exhibit A attached hereto), and cause the Registration Statement to become effective and remain effective as provided herein; provided, however, that not less than three (3) Business Days prior to the filing of the Registration Statement or any related Prospectus or any amendment or supplement thereto, the Company shall (i) furnish to the Special Counsel, copies of all such documents proposed to be filed, which documents (other than those incorporated by reference) will be subject to the review of such Special Counsel, and (ii) at the request of any Holder cause its officers and directors, counsel and independent certified public accountants to respond to such inquiries as shall be necessary, in the reasonable opinion of counsel to such Holders, to conduct a reasonable investigation within the meaning of the Securities Act. The Company shall not file the Registration Statement or any such Prospectus or any amendments or supplements thereto to which the Holders of a majority of the Registrable Securities or the Special Counsel shall reasonably object within three (3) Business Days after their receipt

thereof. In the event of any such objection, the Holders shall provide the Company with any requested revisions to such prospectus or supplement within two (2) Business Days after such objection.

(b)   (i) Prepare and file with the Commission such amendments, including post-effective amendments, to the Registration Statement as may be necessary to keep the Registration Statement continuously effective as to the applicable Registrable Securities for the Effectiveness Period and to the extent any Registrable Securities are not included in such Registration Statement for reasons other than the failure of the Holder to comply with Section 3(m) hereof, shall prepare and file with the Commission such amendments to the Registration Statement or such additional Registration Statements in order to register for resale under the Securities Act all Registrable Securities; (ii) cause the related Prospectus to be amended or supplemented by any required Prospectus supplement, and as so supplemented or amended to be filed pursuant to Rule 424 (or any similar provisions then in force) promulgated under the Securities Act; (iii) respond as promptly as reasonably practicable, and in no event later than ten (10) Business Days to any comments received from the Commission with respect to the Registration Statement or any amendment thereto and as promptly as reasonably practicable provide the Holders true and complete copies of all correspondence from and to the Commission relating to the Registration Statement, but not, without the prior written consent of the Holders, any comments that would result in the disclosure to the Holders of material and non-public information concerning the Company; and (iv) comply in all material respects with the provisions of the Securities Act and the Exchange Act with respect to the disposition of all Registrable Securities covered by the Registration Statement during the applicable period in accordance with the intended methods of disposition by the Holders thereof set forth in the Registration Statement as so amended or in such Prospectus as so supplemented.

(c)   Notify Holders of Registrable Securities to be sold and the Special Counsel as promptly as reasonably practicable (A) when a Prospectus or any Prospectus supplement or post-effective amendment to the Registration Statement is proposed to be filed (but in no event in the case of this subparagraph (A), less than three (3) Business Days prior to date of such filing); (B) when the Commission notifies the Company whether there will be a “review” of such Registration Statement and whenever the Commission comments in writing on such Registration Statement; and (C) with respect to the Registration Statement or any post-effective amendment, when the same has become effective, and after the effectiveness thereof: (i) of any request by the Commission or any other Federal or state governmental authority for amendments or supplements to the Registration Statement or Prospectus or for additional information; (ii) of the issuance by the Commission of any stop order suspending the effectiveness of the Registration Statement covering any or all of the Registrable Securities or the initiation of any Proceedings for that purpose; (iii) of the receipt by the Company of any notification with respect to the suspension of the qualification or exemption from qualification of any of the Registrable Securities for sale in any jurisdiction, or the initiation or threatening of any Proceeding for such purpose; and (iv) if the financial statements included in the Registration Statement become ineligible for inclusion therein or of the occurrence of any event that makes any statement made in the Registration Statement or Prospectus or any document incorporated or deemed to be incorporated therein by reference untrue in any material respect or that requires any revisions to the Registration

Statement, Prospectus or other documents so that, in the case of the Registration Statement or the Prospectus, as the case may be, it will not contain any untrue statement of a material fact or omit to state any material fact required to be stated therein or necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading. Without limitation to any remedies to which the Holders may be entitled under this Agreement, if any of the events described in Section 3(c)(C)(i), 3(c)(C)(ii), 3(c)(C)(iii) or 3(c)(C)(iv) occur, the Company shall use its reasonable best efforts to respond to and correct the event.

(d)   Use its reasonable best efforts to avoid the issuance of, or, if issued, use reasonable best efforts to obtain the withdrawal of, (i) any order suspending the effectiveness of the Registration Statement or (ii) any suspension of the qualification (or exemption from qualification) of any of the Registrable Securities for sale in any jurisdiction, at the earliest practicable time.

(e)   If requested by any Holder of Registrable Securities, (i) promptly incorporate in a Prospectus supplement or post-effective amendment to the Registration Statement such information as the Company reasonably agrees should be included therein and (ii) make all required filings of such Prospectus supplement or such post-effective amendment as soon as reasonably practicable after the Company has received notification of the matters to be incorporated in such Prospectus supplement or post-effective amendment.

(f)   Furnish to each Holder and the Special Counsel, without charge, at least one conformed copy of each Registration Statement and each amendment thereto, including financial statements and schedules, and all exhibits to the extent requested by such Person (including those previously furnished or incorporated by reference) promptly after the filing of such documents with the Commission.

(g)   Promptly deliver to each Holder and the Special Counsel, without charge, as many copies of the Prospectus or Prospectuses (including each form of prospectus) and each amendment or supplement thereto as such Persons may reasonably request; and the Company hereby consents to the use of such Prospectus and each amendment or supplement thereto by each of the selling Holders in connection with the offering and sale of the Registrable Securities covered by such Prospectus and any amendment or supplement thereto.

(h)   Prior to any public offering of Registrable Securities, use its reasonable best efforts to register or qualify or cooperate with the selling Holders and the Special Counsel in connection with the registration or qualification (or exemption from such registration or qualification) of such Registrable Securities for offer and sale under the securities or Blue Sky laws of such jurisdictions within the United States as any Holder requests in writing, to keep each such registration or qualification (or exemption therefrom) effective during the Effectiveness Period and to do any and all other acts or things necessary or advisable to enable the disposition in such jurisdictions of the Registrable Securities covered by a Registration Statement; provided, however, that the Company shall not be required to qualify generally to do business in any jurisdiction where it is

not then so qualified or to take any action that would subject it to general service of process in any jurisdiction where it is not then so subject or subject the Company to any material tax in any such jurisdiction where it is not then so subject.

(i)   Cooperate with the Holders to facilitate the timely preparation and delivery of certificates representing Registrable Securities to be sold pursuant to a Registration Statement, which certificates shall be free, to the extent permitted by applicable law and the Purchase Agreement, of all restrictive legends, and to enable such Registrable Securities to be in such denominations and registered in such names as any Holder may request at least two (2) Business Days prior to any sale of Registrable Securities. In connection therewith, the Company shall promptly after the effectiveness of the Registration Statement cause an opinion of counsel to be delivered to and maintained with its transfer agent, together with any other authorizations, certificates and directions required by the transfer agent, which authorize and direct the transfer agent to issue such Registrable Securities without legend upon sale by the Holder of such shares of Registrable Securities under the Registration Statement.

(j)   Following the occurrence of any event contemplated by Section 3(c)(C)(iv), as promptly as possible, prepare a supplement or amendment, including a post-effective amendment, to the Registration Statement or a supplement to the related Prospectus or any document incorporated or deemed to be incorporated therein by reference, and file any other required document so that, as thereafter delivered, neither the Registration Statement nor such Prospectus will contain an untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading.

(k)   Cause all Registrable Securities relating to such Registration Statement to be listed on any United States securities exchange, quotation system, market or over-the-counter bulletin board on which similar securities issued by the Company are then listed.

(l)   Comply in all material respects with all applicable rules and regulations of the Commission and make generally available to its security holders earnings statements satisfying the provisions of Section 11(a) of the Securities Act and Rule 158 not later than 45 days after the end of any 3-month period (or 90 days after the end of any 12-month period if such period is a fiscal year) commencing on the first day of the first fiscal quarter of the Company after the effective date of the Registration Statement, which statement shall conform to the requirements of Rule 158.

(m)   Request each selling Holder to furnish to the Company information regarding such Holder and the distribution of such Registrable Securities as is required by law or the Commission to be disclosed in the Registration Statement, and the Company may exclude from such registration the Registrable Securities of any such Holder who fails to furnish such information within a reasonable time prior to the filing of each Registration Statement, supplemented Prospectus and/or amended Registration Statement.

If the Registration Statement refers to any Holder by name or otherwise as the holder of any securities of the Company, then such Holder shall have the right to require (if such reference to such Holder by name or otherwise is not required by the Securities Act or any

similar federal statute then in force) the deletion of the reference to such Holder in any amendment or supplement to the Registration Statement filed or prepared subsequent to the time that such reference ceases to be required.

Each Holder agrees by its acquisition of such Registrable Securities that, upon receipt of a notice from the Company of the occurrence of any event of the kind described in Section 3(c)(C)(i), 3(c)(C)(ii), 3(c)(C)(iii), 3(c)(C)(iv), or 3(n), such Holder will forthwith discontinue disposition of such Registrable Securities under the Registration Statement until such Holder’s receipt of the copies of the supplemented Prospectus and/or amended Registration Statement contemplated by Section 3(j), or until it is advised in writing (the “ Advice ”) by the Company that the use of the applicable Prospectus may be resumed, and, in either case, has received copies of any additional or supplemental filings that are incorporated or deemed to be incorporated by reference in such Prospectus or Registration Statement.

(n)   If (i) there is material non-public information regarding the Company which the Company’s Board of Directors (the “ Board ”) reasonably determines not to be in the Company’s best interest to disclose and which the Company is not otherwise required to disclose, or (ii) there is a significant business opportunity (including, but not limited to, the acquisition or disposition of assets (other than in the ordinary course of business) or any merger, consolidation, tender offer or other similar transaction) available to the Company which the Board reasonably determines not to be in the Company’s best interest to disclose and which the Company would be required to disclose under the Registration Statement, then the Company may (i) postpone or suspend filing or effectiveness of a registration statement or (ii) notify the Holders that the Registration Statement may not be used in connection with any sales of the Company’s securities, in each case, for a period not to exceed 30 consecutive days, provided that the Company may not postpone or suspend its obligation under this Section 3(n) for more than 60 days in the aggregate during any 12 month period (each, a “ Blackout Period ”).

4.   Registration Expenses .

All fees and expenses incident to the performance of or compliance with this Agreement by the Company shall be borne by the Company whether or not the Registration Statement is filed or becomes effective and whether or not any Registrable Securities are sold pursuant to the Registration Statement. The fees and expenses referred to in the foregoing sentence shall include, without limitation, (i) all registration and filing fees (including, without limitation, fees and expenses (A) with respect to filings required to be made with each securities exchange, quotation system, market or ove