Document:

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                                                                   EXHIBIT 10.20

                               APPROVAL AGREEMENT

         This APPROVAL AGREEMENT (this "Approval") dated as of March 7, 2006
("Effective Date") is entered into by and between Critical Therapeutics, Inc., a
Delaware corporation ("CRTX") and Kevin J. Tracey, M.D. ("Dr. Tracey").

         WHEREAS, CRTX and Dr. Tracey are parties to a Consulting Agreement
dated as of January 31, 2001, as amended by Amendment No. 1 dated as of January
16, 2003, (the "Agreement"); and

         WHEREAS, the Agreement contemplates that Dr. Tracey will obtain CRTX's
approval prior to rendering advice or services in the Field to a for-profit
entity;

         WHEREAS, Dr. Tracey has requested that CRTX grant such approval in
connection with the proposed formation by Dr. Tracey and others of, and Dr.
Tracey's continuing involvement with, a new for-profit entity to be known as
Innovative Metabolics, Inc. ("IMI"), and CRTX has agreed to such request,
subject to the terms and conditions set forth herein;

NOW, THEREFORE, the parties hereto agree as follows:

1. Definitions; References. Unless otherwise specifically defined herein, each
term used herein (including in the Recitals hereof) which is defined in the
Agreement shall have the meaning assigned to such term in the Agreement.

2. Approval. As contemplated by Section 1.4(a) of the Agreement, and subject to
the conditions specified in Section 3 of this Approval, CRTX hereby approves the
rendering by Dr. Tracey of advice and services in the Field to IMI solely with
respect to CRTX's technology related to physical and electrical stimulation of
the vagus nerve. For purposes of clarity, the use of Confidential Information
(as defined in Section 6.2 of the Agreement) in the area of CRTX's technology
related to physical and electrical stimulation of the vagus nerve shall not
produce any Inventions (as defined in Section 5.1 of the Agreement) for purposes
of the Agreement for as long as this Approval is in effect.

3. Conditions of Continued Effectiveness Of Approval.

(a) The approval contained in Section 2 of this Approval shall remain in effect
for the duration of the Agreement but only so long as each of the following
conditions is satisfied (or in the case of the conditions specified in (a)(2)
and (a)(3) below, is capable of being satisfied within the time period indicated
in such condition):

         (1) Dr. Tracey shall promptly become and remain an owner of shares of
         the common stock of Innovative Metabolics, Inc. ("IMI").

         (2) The negotiation and execution, on or prior to the one year
         anniversary of the Effective Date, of a license agreement relating to
         CRTX's technology related to

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         physical and electrical stimulation of the vagus nerve between CRTX and
         IMI, on terms agreeable to each of the parties to such license
         agreement. For avoidance of doubt, Dr. Tracey acknowledges that CRTX is
         not obligated to enter into such a license agreement and that CRTX may,
         in its sole discretion, at any time and for any reason terminate
         negotiations regarding such license agreement, in which case the
         approval contained in Section 2 would terminate.

         (3) IMI completes a round of equity financing (which may include an
         issuance of convertible debt) on or prior to the one year anniversary
         of the Effective Date, which provides immediate gross proceeds to IMI
         of not less than $1,000,000.

(b) Except as expressly provided in this Approval, the Agreement shall remain
unchanged and in full force and effect and is hereby ratified and confirmed in
all respects.

5. Miscellaneous.

(a) Dr. Tracey acknowledges and agrees that the execution and delivery by CRTX
of this Approval shall not be deemed to create a course of dealing or an
obligation to execute similar approvals, waivers or amendments under the same or
similar circumstances in the future.

(b) This Approval shall be binding upon and inure to the benefit of the parties
hereto and to the Agreement and their respective successors and assigns.

(c) This Approval shall be governed by and construed in accordance with the law
of the Commonwealth of Massachusetts without regard to any choice of law
principle that would dictate the application of the law of another jurisdiction.

(d) This Approval may be executed in any number of counterparts, each of which
shall be deemed an original, but all such counterparts together shall constitute
but one and the same instrument. Each of the parties hereto understands and
agrees that this document (and any other document required herein) may be
delivered by any party thereto either in the form of an executed original or an
executed original sent by facsimile transmission to be followed promptly by
mailing of a hard copy original, and that receipt of a facsimile transmitted
document purportedly bearing the signature of Dr. Tracey or CRTX shall bind Dr.
Tracey or CRTX, respectively, with the same force and effect as the delivery of
a hard copy original.

(e) This Approval contains the entire and exclusive agreement of the parties
hereto with reference to the matters discussed herein. This Approval supersedes
all prior drafts and communications with respect hereto. This Approval may not
be amended except in accordance with the provisions of Section 8.5 of the
Agreement.

(f) If any term or provision of this Approval shall be deemed prohibited by or
invalid under any applicable law, such provision shall be invalidated without
affecting the remaining provisions of this Approval or the Agreement.

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         IN WITNESS WHEREOF, the parties hereto have caused this Approval to be
duly executed as of the day and year first above written.

                                       CRITICAL THERAPEUTICS, INC.

                                       /s/ Trevor Phillips
                                      -----------------------------------------
                                      Trevor Phillips
                                      Chief Operating Officer

                                      KEVIN J. TRACEY, M.D.

                                      /s/ Kevin J. Tracey, MD
                                       ----------------------------------------

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                                                                   EXHIBIT 10.24

                       FOURTH LOAN MODIFICATION AGREEMENT

      This Fourth Loan Modification Agreement (this "Loan Modification
Agreement") is entered into as of January 6, 2006, by and between SILICON VALLEY
BANK, a California-chartered bank, with its principal place of business at 3003
Tasman Drive, Santa Clara, California 95054 and with a loan production office
located at One Newton Executive Park, Suite 200, 2221 Washington Street, Newton,
Massachusetts 02462 ("Bank") and CRITICAL THERAPEUTICS, INC., a Delaware
corporation with its chief executive office located at 60 Westview Street,
Lexington, Massachusetts 02421 ("Borrower").

1.    DESCRIPTION OF EXISTING INDEBTEDNESS AND OBLIGATIONS. Among other
      indebtedness and obligations which may be owing by Borrower to Bank,
      Borrower is indebted to Bank pursuant to a certain loan arrangement dated
      as of June 28, 2002, evidenced by, among other documents, a certain Loan
      and Security Agreement dated as of June 28, 2002, between Borrower and
      Bank, as amended by a certain Loan Modification Agreement dated as of
      December 11, 2002, between Borrower and Bank, as amended by a certain
      Second Loan Modification Agreement dated as of April 10, 2003, between
      Borrower and Bank, and as further amended by a certain Third Loan
      Modification Agreement dated as of June 30, 2004, between Borrower and
      Bank (as may be further amended from time to time, the "Loan Agreement").
      Capitalized terms used but not otherwise defined herein shall have the
      same meaning as in the Loan Agreement.

2.    DESCRIPTION OF COLLATERAL. Repayment of the Obligations is secured by the
      Collateral as described in the Loan Agreement (together with any other
      collateral security granted to Bank, the "Security Documents").

            Hereinafter, the Security Documents, together with all other
      documents evidencing or securing the Obligations shall be referred to as
      the "Existing Loan Documents".

3.    DESCRIPTION OF CHANGE IN TERMS.

      A.    Modifications to Loan Agreement.

            1.    The Loan Agreement is hereby amended by deleting the date
                  "December 31, 2005" appearing in Section 2.1.4 (a) and
                  inserting the date "March 31, 2006" thereof.

            2.    The Loan Agreement is hereby amended by deleting the follow
                  Section 6.2 entitled "Financial Statements, Reports,
                  Certificates " in its entirety:

                  "6.2  Financial Statement, Report, Certificates.

                  Borrower shall deliver to Bank: (i) as soon as available, but
                  no later than thirty (30) days after the last day of each
                  month, a Compliance Certificate signed by a Responsible Office
                  in the Form of Exhibit C, together with a company prepared
                  consolidated balance sheet and income statement covering
                  Borrower's consolidated operations during the period certified
                  by a Responsible Officer and in a form acceptable to Bank;
                  (ii) as soon as available, but no later than one hundred and
                  twenty (120) days after the last day of Borrower's fiscal
                  year, a Compliance Certificate signed by a Responsible

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                  Office in the form of Exhibit C, together with audited
                  consolidated financial statements prepared under GAAP,
                  consistently applied, together with an unqualified opinion on
                  the financial statements from an independent certified public
                  accounting firm reasonably acceptable to Bank; (iii) in the
                  event that the Borrower's stock becomes publicly held, within
                  five (5) days of filing, copies of all statements, reports and
                  notices made available to Borrower's security holders or to
                  any holders of Subordinated Debt and all reports on Form 10-K,
                  10-Q and 8-K filed with the Securities and Exchange
                  Commission; (iv) a prompt report of any legal actions pending
                  or threatened against Borrower or any Subsidiary that could
                  result in damages or costs to Borrower or any Subsidiary of
                  One Hundred Thousand Dollars ($100,000.00) or more; (v)
                  annually, but not later than fifteen (15) days after Board
                  Approval, budgets, sales projections and operating plans, and
                  (vi) other financial information reasonably requested by Bank.

                  and inserting in lieu thereof the following:

                  "6.2  Financial Statements, Reports, Certificates.

                        Borrower shall deliver to Bank: (i) for each month in
                  which the unrestricted cash of the Borrower, as set forth on
                  its balance sheet is less than Fifteen Million Dollars
                  ($15,000,000.00), a company prepared consolidated balance
                  sheet and income statement covering Borrower's consolidated
                  operations during the period certified by a Responsible
                  Officer and in a form acceptable to Bank; (ii) within five (5)
                  days of filing, copies of or electronic notice of links to all
                  statements, reports and notices made available to Borrower's
                  security holders or to any holders of Subordinated Debt and
                  all reports on Form 10-K, 10-Q and 8-K filed with the
                  Securities and Exchange Commission; (iii) a prompt report of
                  any legal actions pending or threatened against Borrower or
                  any Subsidiary that could result in damages or costs to
                  Borrower or any Subsidiary of Three Hundred Thousand Dollars
                  ($300,000.00) or more; (iv) annually, but not later than
                  fifteen (15) days after Board Approval, final budgets, sales
                  projections and operating plans, and (v) other financial
                  information reasonably requested by Bank."

            3.    The Loan Agreement shall be amended by deleting the follow
                  Section 6.3 entitled "Inventory; Returns " in its entirety:

                  "6.3  Inventory; Returns. Borrower shall keep all Inventory in
                  good and marketable condition, free from material defects.
                  Returns and allowances between Borrower and its account
                  debtors shall follow Borrower's customary practices as they
                  exist at the Closing Date. Borrower must promptly notify Bank
                  of all returns, recoveries, disputes and claims that involve
                  more than Fifty Thousand Dollars ($50,000.00)."

                  and inserting in lieu thereof:

                  "6.3  Inventory; Returns. Borrower shall keep all
                  Inventory in good and marketable condition, free from material
                  defects. Returns and allowances between Borrower and its
                  account debtors shall follow Borrower's customary practices as
                  they exist at the Closing Date. Borrower must promptly notify
                  Bank of all returns, recoveries, disputes and claims that
                  involve more than Five Hundred Thousand Dollars
                  ($500,000.00)."

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            4.    The Loan Agreement is hereby amended by deleting the following
                  definitions appearing in Section 13.1 thereof:

                        ""2004 EQUIPMENT LINE" is a 2004 Equipment Advance or
                        2004 Equipment Advances of up to Three Million Dollars
                        ($3,000,000.00)."

                        ""2004/2005 OTHER EQUIPMENT" is leasehold improvements,
                        transferable software licenses, and other soft costs
                        approved by the Bank, including sales tax, freight and
                        installation expenses. Unless otherwise agreed to by
                        Bank, not more than 30% of the proceeds of either the
                        2004 Equipment Line or the 2005 Equipment Line shall be
                        used to finance 2004/2005 Other Equipment."

                        ""2005 EQUIPMENT LINE" is a 2005 Equipment Advance or
                        2005 Equipment Advances of up to the lesser of (i) Three
                        Million Dollars ($3,000,000.00) minus the aggregate
                        original principal amount of all 2004 Equipment Advances
                        made hereunder or (ii) One Million Three Hundred
                        Thousand Dollars ($1,300,000.00)."

                  and insert in lieu thereof the following:

                        ""2004 EQUIPMENT LINE" is a 2004 Equipment Advance or
                        2004 Equipment Advances of up to Three Million Five
                        Hundred Thousand Dollars ($3,500,000.00)."

                        ""2004/2005 OTHER EQUIPMENT" is leasehold improvements,
                        transferable software licenses, and other soft costs
                        approved by the Bank, including sales tax, freight and
                        installation expenses. Unless otherwise agreed to by
                        Bank, not more than 35% of the proceeds of either the
                        2004 Equipment Line or the 2005 Equipment Line shall be
                        used to finance 2004/2005 Other Equipment."

                        ""2005 EQUIPMENT LINE" is a 2005 Equipment Advance or
                        2005 Equipment Advances of up to Three Million Five
                        Hundred Thousand Dollars ($3,500,000.00) minus the
                        aggregate original principal amount of all 2004
                        Equipment Advances and 2005 Equipment Advances made
                        hereunder (for clarification, such available amount, as
                        of the date of this Loan Modification Agreement is in an
                        amount not to exceed Five Hundred Seventy-Six Thousand
                        Nineteen Dollars and 85/100 ($576,019.85)."

            5.    The Compliance Certificate appearing as Exhibit C to the Loan
                  Agreement is hereby deleted in its entirety.

      B.    Waivers.

            1.    Bank hereby waives Borrower's existing defaults under the Loan
                  Agreement by virtue of Borrower's failure to comply with the
                  financial reporting requirements set forth in Section
                  6.2(a)(i) thereof as of the months ending July 31, 2005, and
                  August 31, 2005. Bank's waiver of Borrower's compliance of
                  said affirmative covenant shall apply only to the foregoing
                  specific periods.

4.    FEES. Borrower shall reimburse Bank for all legal fees and expenses
      incurred in connection with this

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      amendment to the Existing Loan Documents.

5.    RATIFICATION OF NEGATIVE PLEDGE AGREEMENT. Borrower hereby ratifies,
      confirms and reaffirms, all and singular, the terms and conditions of a
      certain Negative Pledge Agreement dated as of June 28, 2002 between
      Borrower and Bank, and acknowledges, confirms and agrees that said
      Negative Pledge Agreement shall remain in full force and effect.

6.    RATIFICATION OF PERFECTION CERTIFICATE. Borrower hereby ratifies, confirms
      and reaffirms, all and singular, the terms and disclosures contained in a
      certain Perfection Certificate dated as of June 30, 2004, between Borrower
      and Bank, and acknowledges, confirms and agrees the disclosures and
      information above Borrower provided to Bank in the Perfection Certificate
      has not changed, as of the date hereof.

7.    CONSISTENT CHANGES. The Existing Loan Documents are hereby amended
      wherever necessary to reflect the changes described above.

8.    RATIFICATION OF LOAN DOCUMENTS. Borrower hereby ratifies, confirms, and
      reaffirms all terms and conditions of all security or other collateral
      granted to the Bank, and confirms that the indebtedness secured thereby
      includes, without limitation, the Obligations.

9.    NO DEFENSES OF BORROWER. Borrower hereby acknowledges and agrees that
      Borrower has no offsets, defenses, claims, or counterclaims against Bank
      with respect to the Obligations, or otherwise, and that if Borrower now
      has, or ever did have, any offsets, defenses, claims, or counterclaims
      against Bank, whether known or unknown, at law or in equity, all of them
      are hereby expressly WAIVED and Borrower hereby RELEASES Bank from any
      liability thereunder.

10.   CONTINUING VALIDITY. Borrower understands and agrees that in modifying the
      existing Obligations, Bank is relying upon Borrower's representations,
      warranties, and agreements, as set forth in the Existing Loan Documents.
      Except as expressly modified pursuant to this Loan Modification Agreement,
      the terms of the Existing Loan Documents remain unchanged and in full
      force and effect. Bank's agreement to modifications to the existing
      Obligations pursuant to this Loan Modification Agreement in no way shall
      obligate Bank to make any future modifications to the Obligations. Nothing
      in this Loan Modification Agreement shall constitute a satisfaction of the
      Obligations. It is the intention of Bank and Borrower to retain as liable
      parties all makers of Existing Loan Documents, unless the party is
      expressly released by Bank in writing. No maker will be released by virtue
      of this Loan Modification Agreement.

11.   COUNTERSIGNATURE. This Loan Modification Agreement shall become effective
      only when it shall have been executed by Borrower and Bank.

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      This Loan Modification Agreement is executed as a sealed instrument under
the laws of the Commonwealth of Massachusetts as of the date first written
above.

BORROWER:                                        BANK:

CRITICAL THERAPEUTICS, INC.                      SILICON VALLEY BANK

By: /s/ FRANK E. THOMAS                          By:  /s/ BERNADETTE M. MICHAUD
    -------------------                               --------------------------

Name: Frank E. Thomas                            Name: Bernadette M. Michaud

Title: Chief Financial Officer, Senior Vice      Title: VP
       President Of Finance and Treasurer

      The undersigned, CTI SECURITIES CORP., a Massachusetts corporation,
ratifies, confirms and reaffirms, all and singular, the terms and conditions of
a certain Unconditional Guaranty dated December 3, 2003 (the "Guaranty") and a
certain Security Agreement dated December 3, 2003 (the "Security Agreement") and
acknowledges, confirms and agrees that the Guaranty and the Security Agreement
shall remain in full force and effect and shall in no way be limited by the
execution of this Loan Modification Agreement, or any other documents,
instruments and/or agreements executed and/or delivered in connection herewith.

                                       CTI SECURITIES CORP.

                                       By:  /s/ FRANK E. THOMAS
                                            -------------------

                                       Name: Frank E. Thomas

                                       Title: Treasurer

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