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                                                                   EXHIBIT 10.23


                                                  September 4, 2001

Mark M. Brady
2000 Tropez Lane
Cary, NC 27511

Dear Mr. Brady:

     This letter sets forth the terms and conditions under which LipoMed, Inc.
(the "Company") will employ you as an employee of the Company effective
September 4, 2001 and ending September 4, 2002 (the "Initial Term"). Subsequent
to the Initial Term, this letter agreement shall be renewed on a year-to-year
basis on the same terms and conditions set forth in this letter (each a "Renewal
Term") unless terminated as provided herein or unless amended or modified by
mutual agreement. The Initial Term and any Renewal Term(s) are referred to
herein collectively as the "Term". You will serve as Vice President and Chief
Commercial Officer.

     The compensation for your services during the Term shall be as follows: (i)
a base salary of One Hundred Seventy-Five Thousand dollars ($175,000) for the
first year to be paid consistent with the payroll schedule established by the
Company; (ii) such options as the Board of Directors may in its discretion
approve; (iii) four weeks of vacation per fiscal year; and (iv) other employee
benefits as those become available and as those benefits are provided to other
employees of the Company. In addition, the Company will pay all reasonable
expenses incurred by you which are related to the conduct of the business of the
Company, provided that you comply with the policies for reimbursement or advance
expenses as established by the Board of Directors of the Company.

     This agreement may be voluntarily terminated by either party by giving
written notice of intention not to renew for any Renewal Term to the other party
("Voluntary Termination"), such notice to be delivered at least sixty (60) days
prior to the last day of the Initial Term or any Renewal Term. In the event that
the Company terminates this agreement other than by Voluntary Termination or for
"cause" (as hereinafter defined) or due to your death or permanent disability or
the liquidation, dissolution or discontinuance of business of the Company, the
Company shall pay you your most current base salary for a period of six (6)
months following such termination (the "Severance Period") and you shall be
entitled to all benefits which were provided to you at the time of such
termination during the Severance Period to the extent allowed under the terms of
the applicable benefit plans (or if not allowed, the cash equivalent thereof).
Notwithstanding the foregoing, no further Severance Benefits will be paid after
you commence comparable employment after such termination. For the purposes of
this paragraph, "Cause" shall be determined by the Board of Directors and shall
mean:

     (i)   any material breach of this agreement by you or failure by you to
           diligently and properly perform your duties for the Company, such
           failure to be determined in the reasonable judgment of the Board of
           Directors of the Company and which failure is not corrected within
           thirty (30) days after notice of such failure;

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     (ii)  any material failure to comply with the policies and/or directives of
           the Board of Directors which failure is not corrected within thirty
           (30) days after notice of such failure;

     (iii) Any action by you that is dishonest, illegal or not in good faith
           which is materially detrimental to the interest and well-being of the
           Company; or

     (iv)  Any failure by you to fully disclose any material conflict of
           interest you may have with the Company in a transaction between the
           Company and any third party which is materially detrimental to the
           interest and well-being of the Company; or

     (v)   Any adverse act or omission by you which would be required to be
           disclosed pursuant to federal or state securities laws or which would
           limit the ability of the Company or any entity affiliated with the
           Company to sell securities under any Federal or state law or which
           would disqualify the Company or any affiliated entity from any
           exemption otherwise available to it, all of which are materially
           detrimental to the interest and well-being of the Company.

     This letter agreement and the services rendered by you hereunder will be
contingent upon and subject to that certain Confidentiality, Inventions and
Non-Competition Agreement by and between the Company and you dated January 1,
2001 (the "Non-Competition Agreement").

     You hereby represent that your performance of services for the Company will
not violate any obligation which you may have to any previous employer,
including, without limitation, any agreements to refrain from competing,
directly or indirectly, with the business of any previous employer or any other
third party. You further represent that your performance of all the terms of
this agreement and as a consultant to the Company, if applicable, does not and
will not breach any agreement to keep in confidence proprietary information,
trade secrets, knowledge or data acquired by you in confidence or in trust prior
to your engagement or employment by the Company or induce the Company to use any
confidential or proprietary information, trade secrets or material belonging to
any previous employer or others, and you agree to indemnify and hold harmless
the Company from and against all claims of loss or liability (including
reasonable attorneys' fees) arising out of or connected with your breach or
alleged breach of any of the representations set forth above.

     The Company will indemnify and hold you harmless to the fullest extent
permitted by law from and against any and all claims of loss or liability
(including reasonable attorney's fees) arising from or in connection with this
agreement or the services provided hereunder, except to the extent that the same
shall be determined to have resulted solely from actions taken or omitted due to
your willful misconduct, negligence or knowing violation of the law.

     This agreement supersedes in its entirety any previous employment or
consulting agreements between you and the Company, including without limitation,
that certain employment letter agreement between you and the Company dated
November 30, 2000 and accepted by you December 28, 2000, and, with the
Non-Competition Agreement, constitutes a full and complete understanding of the
parties with respect to

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the subject matter hereof, and all prior written and oral agreements concerning
the subject matter hereof are hereby terminated. This agreement shall be
governed by the laws of the State of North Carolina.

     If you are in agreement with the terms and conditions set forth herein,
please execute one copy of this letter and return it to me.

                                           Sincerely,

                                           LipoMed, Inc.

                                           /s/ F. Ronald Stanton
                                           -------------------------------------
                                           F. Ronald Stanton
                                           President and Chief Executive Officer

Agreed to and accepted this
15/th/ day of October, 2001.

/s/ Mark M. Brady
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Mark M. Brady