WARRANT AND REPURCHASE AGREEMENT

Exhibit 10.12

Execution Copy

THE SECURITIES REPRESENTED BY THIS INSTRUMENT WERE ORIGINALLY ISSUED ON MARCH 4, 2004, AND HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS AMENDED, OR UNDER ANY STATE SECURITIES LAW.

WARRANT
AND REPURCHASE AGREEMENT

FOR VALUE RECEIVED, Sparhawk Laboratories, Inc., a Missouri corporation (the “ Company ”), hereby grants to Chemdex, Inc., a Kansas corporation (the “ Purchaser ”) (the Purchaser is also referred to herein as the “ Holder ”), the right to purchase from the Company sixty-nine (69) units of the Warrant Equity, subject to adjustment as provided below, at a price per unit of $1.00 (as adjusted from time to time hereunder, the “ Exercise Price ”).  This Warrant and Repurchase Agreement (the “ Warrant ”) is issued pursuant to an Investor Representation Letter, dated as of March 4, 2004 (the “ Purchase Agreement ”), between the Company and the Purchaser.

The amount and kind of securities obtainable pursuant to the rights granted hereunder and the purchase price for such securities are subject to adjustment pursuant to the provisions contained in this Warrant.

This Warrant is subject to the following provisions:

Section 1.              Exercise of Warrant.

1A.          Exercise Period; Expiration Date .

(i)            The Holder may exercise, in whole or in part, the purchase rights represented by this Warrant at any time and from time to time beginning on the day after the fifth anniversary of the Date of Issuance (unless the Warrant expires prior to such date as provided in Section 1A(ii) hereof) to and including (if later) the Expiration Date (the “Exercise Period”).  If the Warrant has not expired prior to the day after the fifth anniversary of the Date of Issuance, then thereafter the Company shall give the Holder written notice of the expiration of the Exercise Period at least 30 days but not more than 90 days prior to the end of the Exercise Period.

(ii)           This Warrant shall expire on the earlier of (i)  the tenth anniversary of the Date of Issuance or (ii)  the date on which all principal, interest, premiums (if any) and other amounts due in respect of the Unsecured Subordinated Note have been paid in full (the “ Expiration Date ”), even if the Expiration Date precedes the start of the Exercise Period.

1B.          Exercise Procedure .

(i)            This Warrant shall be deemed to have been exercised when the Company has received all of the following items (the “ Exercise Time ”):

(a)           a completed Exercise Agreement, as described in Section 1C below, executed by the Holder exercising all or part of the purchase rights represented by this Warrant;

(b)           this Warrant; and

(c)           a check payable to the Company in an amount equal to the product of the Exercise Price multiplied by the amount of Warrant Equity being purchased upon such exercise.

(ii)           Certificates for units of Warrant Equity purchased upon exercise of this Warrant shall be delivered by the Company to the Holder within 5 Business Days after the date of the Exercise Time.  Unless this Warrant has expired or all of the purchase rights represented hereby have been exercised, the Company shall prepare a new Warrant, substantially identical hereto, representing the rights formerly represented by this Warrant which have not expired or been exercised and shall, within such 5-Business Day period, deliver such new Warrant to the Holder.

(iii)          The Warrant Equity issuable upon the exercise of this Warrant shall be deemed to have been issued to the Holder at the Exercise Time, and the Holder shall be deemed for all purposes to have become the record holder of such Warrant Equity at the Exercise Time.

(iv)          The issuance of certificates for Warrant Equity upon exercise of this Warrant shall be made without charge to the Holder for any issuance Tax in respect thereof or other cost incurred by the Company in connection with such exercise and the related issuance of Warrant Equity.  Each unit of Warrant Equity issuable upon exercise of this Warrant shall, upon payment of the Exercise Price therefor, be fully paid and nonassessable and free from all Taxes and Liens.

(v)           The Company shall not close its books against the transfer of this Warrant or of any amount of Underlying Warrant Equity in any manner which interferes with the timely exercise of this Warrant.  If applicable, the Company shall from time to time take all such action as may be necessary to assure that the par value per unit of the unissued Warrant Equity acquirable upon exercise of this Warrant is at all times equal to or less than the sum of the Exercise Price then in effect and the per unit price paid for this Warrant.

(vi)          The Company shall assist and cooperate with any Holder required to make any governmental filings or obtain any governmental approvals prior to or in connection with any exercise of this Warrant (including, without limitation, making any filings required to be made by the Company).

(vii)         Notwithstanding any other provision hereof, if an exercise of any portion of this Warrant is to be made in connection with a sale of the Company, the exercise of any portion of this Warrant may, at the election of the holder hereof, be conditioned upon the sale of

2

the Company, in which case such exercise shall not be deemed to be effective until the consummation of such transaction.

(viii)        The Company shall at all times reserve and keep available out of its authorized but unissued units of Warrant Equity solely for the purpose of issuance upon the exercise of this Warrant, such amount of Warrant Equity issuable upon the exercise of this Warrant.  The Company shall take all such actions as may be necessary to assure that all such units of Warrant Equity may be so issued without violation of any applicable law or governmental regulation or any requirements of any securities exchange upon which units of Warrant Equity may be listed (except for official notice of issuance which shall be immediately delivered by the Company upon each issuance).  The Company shall not take any action which would cause the amount of authorized but unissued unites of Warrant Equity to be less than the amount of such units required to be reserved hereunder for issuance upon exercise of this Warrant.

1C.          Exercise Agreement .  Upon any exercise of this Warrant, the Exercise Agreement shall be substantially in the form set forth in Exhibit I hereto.  Such Exercise Agreement shall be dated the actual date of execution thereof.

1D.          Effect of Exercise .  Upon exercise of this Warrant, the Company shall stamp “EXERCISED” on the face of this Warrant and return the original Warrant to the Holder, it being understood that all of the Holders’ and the Company’s rights and obligations under this Warrant shall survive the exercise hereof.

Section 2.              Adjustment of Exercise Price and Number of Units.   In order to prevent dilution of the rights granted under this Warrant, the Exercise Price shall be subject to adjustment from time to time as provided in this Section, and the amount of Warrant Equity obtainable upon exercise of this Warrant shall be subject to adjustment from time to time as provided in this Section.

2A.          Adjustment of Exercise Price and Amount of Warrant Equity .

(i)            The initial Exercise Price shall be $1.00 per unit of Warrant Equity.

(ii)           If and whenever on or after the Date of Issuance, the Company issues or sells, or in accordance with this Section is deemed to have issued or sold, any units of Warrant Equity for a consideration per unit less than $1,800 (as such amount is proportionately adjusted for splits, combinations, distributions and recapitalizations affecting the Warrant Equity after the original date of issuance of this Warrant, the “ Base Price ”), then immediately upon such issue or sale the Exercise Price shall be reduced to the Exercise Price determined by multiplying the Exercise Price in effect immediately prior to such issue or sale (or deemed issue or sale) by a fraction, the numerator of which shall be the sum of (1) the amount of Warrant Equity Deemed Outstanding immediately prior to such issue or sale (or deemed issue or sale) multiplied by the Base Price as of the date of such issue or sale (or deemed issue or sale), plus (2) the consideration, if any, received by the Company upon such issue and sale (or deemed issue or sale), and the denominator of which shall be the product derived by multiplying the Base Price

3

by the amount of Warrant Equity Deemed Outstanding immediately after such issue or sale (or deemed issue or sale).

(iii)          Upon each such adjustment of the Exercise Price hereunder, the amount of Warrant Equity acquirable upon exercise of this Warrant shall be adjusted to the amount of Warrant Equity determined by multiplying the Exercise Price in effect immediately prior to such adjustment by the amount of Warrant Equity acquirable upon exercise of this Warrant immediately prior to such adjustment and dividing the product thereof by the Exercise Price resulting from such adjustment.

(iv)          No adjustment under this Section 2 shall be made in connection with the issuance of (i) up to 166 units of Warrant Equity to officers, directors or employees of the Company pursuant to equity incentive plans, (ii) any issuance of Warrant Equity pursuant to the terms of the warrants issued to C3 pursuant to the Senior Loan Agreement, (iii) any issuance of Warrant Equity pursuant to the terms of the warrants issued to Walco pursuant to the Junior Loan Agreement, (iv) any issuance of Warrant Equity pursuant to this Warrant, and (v) any issuance of Equity Interests pursuant to the exercise of preemptive rights granted to Messrs. John U. Bascom and E. Bert Hughes in Section 11 of the Shareholders Agreement; provided, that, the exclusion in this part (v) shall not be deemed to include the proposed issuance of Equity Interests by the Company to which such preemptive rights become exercisable.

2B.          Effect on Exercise Price of Certain Events .  For purposes of determining the adjusted Exercise Price and amount of Warrant Equity acquirable upon exercise of this Warrant under this Section, the following shall be applicable:

(i)            Issuance of Rights or Options .  If the Company in any manner grants or sells any Options and the price per unit for which Warrant Equity is issuable upon the exercise of such Options, or upon conversion or exchange of any Convertible Securities issuable upon exercise of such Options, is less than the Base Price determined immediately prior to such granting or sale, then immediately upon such issue or sale in effect immediately prior to the time of the granting or sale of such Options, then the total maximum amount of Warrant Equity issuable upon the exercise of such Options, or upon conversion or exchange of the total maximum amount of such Convertible Securities issuable upon the exercise of such Options, shall be deemed to be outstanding and to have been issued and sold by the Company at the time of the granting or sale of such Option for such price per unit.  For purposes of this paragraph, the “ price per unit for which Warrant Equity is issuable upon exercise of such Options, or upon conversion or exchange of such Convertible Securities ” is determined by dividing (A) the total amount, if any, received or receivable by the Company as consideration for the granting or sale of such Options, plus the minimum aggregate amount of additional consideration payable to the Company upon the exercise of all such Options, plus in the case of such Options which relate to Convertible Securities, the minimum aggregate amount of additional consideration, if any, payable to the Company upon the issuance or sale of such Convertible Securities and the conversion or exchange thereof, by (B) the total maximum amount of Warrant Equity issuable upon the exercise of such Options or upon the conversion or exchange of all such Convertible Securities issuable upon the exercise of such Options.  No adjustment under this Section shall be made upon the actual issuance of such Warrant Equity or of such Convertible Securities upon the

4

exercise of such Options or upon the actual issuance of such Warrant Equity upon conversion or exchange of such Convertible Securities.

(ii)           Issuance of Convertible Securities .  If the Company in any manner issues or sells any Convertible Securities and the price per unit for which Warrant Equity is issuable upon conversion or exchange thereof is less than the Base Price determined immediately prior to such issuance or sale, then the maximum amount of Warrant Equity issuable upon conversion or exchange of all such Convertible Securities shall be deemed to be outstanding and to have been issued and sold by the Company at the time of the issuance or sale of such Convertible Securities for such price per unit.  For the purposes of this paragraph, the “ price per unit for which Warrant Equity is issuable upon conversion or exchange thereof ” is determined by dividing (A) the total amount received or receivable by the Company as consideration for the issue or sale of such Convertible Securities, plus the minimum aggregate amount of additional consideration, if any, payable to the Company upon the conversion or exchange thereof, by (B) the total maximum amount of Warrant Equity issuable upon the conversion or exchange of all such Convertible Securities.  No adjustment under this Section shall be made upon the actual issuance of such Warrant Equity upon conversion or exchange of such Convertible Securities, and if any such issuance or sale of such Convertible Securities is made upon exercise of any Options for which adjustments of the Exercise Price had been or are to be made pursuant to other provisions of this Section, no further adjustment of the Exercise Price shall be made by reason of such issue or sale.

(iii)          Change in Option Price or Warrant Rate .  If the purchase price provided for in any Option, the additional consideration (if any) payable upon the issuance, conversion or exchange of any Convertible Security, or the rate at which any Convertible Security is convertible into or exchangeable for Warrant Equity changes at any time, the Exercise Price in effect at the time of such change shall be adjusted immediately to the Exercise Price which would have been in effect at such time had such Option or Convertible Security originally provided for such changed purchase price, additional consideration or changed conversion rate, as the case may be, at the time initially granted, issued or sold and the amount of Warrant Equity shall be correspondingly adjusted; provided , that if such adjustment of the Exercise Price would result in an increase in the Exercise Price then in effect, such adjustment shall not be effective until 30 days after written notice thereof has been given to all Holders.  For purposes of this Section, if the terms of any Option or Convertible Security which was outstanding as of the Date of Issuance are changed in the manner described in the immediately preceding sentence, then such Option or Convertible Security and the Warrant Equity deemed issuable upon exercise, conversion or exchange thereof shall be deemed to have been issued as of the date of such change; provided , that no such change shall at any time cause the Exercise Price to be increased.

(iv)          Treatment of Expired Options and Unexercised Convertible Securities .  Upon the expiration of any Option or the termination of any right to convert or exchange any Convertible Securities without the exercise of such Option or right, the Exercise Price then in effect and the amount of Warrant Equity acquirable hereunder shall be adjusted immediately to the Exercise Price which would have been in effect at the time of such expiration or termination had such Option or Convertible Securities, to the extent outstanding immediately prior to such expiration or termination, never been issued; provided , that if such expiration or termination would result in an increase in the Exercise Price then in effect, such increase shall not be

5

effective until 30 days after written notice thereof has been given to all Holders.   For purposes of this Section, the expiration or termination of any Option or Convertible Security which was outstanding as of the date of issuance of this Warrant shall not cause the Exercise Price hereunder to be adjusted unless, and only to the extent that, a change in the terms of such Option or Convertible Security caused it to be deemed to have been issued after the date of issuance of this Warrant.

(v)           Calculation of Consideration Received .  If any Warrant Equity, Options or Convertible Securities are issued or sold or deemed to have been issued or sold for cash, the consideration received therefor shall be deemed to be the net amount received by the Company therefor.  In case any Warrant Equity, Options or Convertible Securities are issued or sold for a consideration other than cash, the amount of the consideration other than cash received by the Company shall be the fair value of such consideration, except where such consideration consists of securities, in which case the amount of consideration received by the Company shall be the Market Price thereof as of the date of receipt.  In case any Warrant Equity, Options or Convertible Securities are issued to the owners of the non-surviving entity in connection with any merger in which the Company is the surviving entity, the amount of consideration therefor shall be deemed to be the fair value of such portion of the net assets and business of the non-surviving entity as is attributable to such Warrant Equity, Options or Convertible Securities, as the case may be.  The fair value of any consideration other than cash and securities shall be determined jointly by the Company and the Majority Warrant Holders.  If such parties are unable to reach agreement within a reasonable period of time, such fair value shall be determined by an appraiser jointly selected by the Company and the Majority Warrant Holders.  The determination of such appraiser shall be final and binding upon the parties, and the fees and expenses of such appraiser shall be borne by the Company.

(vi)          Integrated Transactions .  In case any Option or Convertible Security is issued in connection with the issue or sale of other Equity Interests of the Company, together comprising one integrated transaction in which no specific consideration is allocated to such Options or Convertible Securities by the parties thereto, the Options and Convertible Securities shall be deemed to have been issued without consideration.

(vii)         Treasury Units .  The amount of Warrant Equity outstanding at any given time does not include units owned or held by or for the account of the Company or any of its Subsidiaries, and the disposition of any units so owned or held shall be considered an issue or sale of Warrant Equity.

(viii)        Record Date .  If the Company takes a record of the holders of Warrant Equity for the purpose of entitling them (A) to receive a Dividend payable in Warrant Equity, Options or in Convertible Securities or (B) to subscribe for or purchase Warrant Equity, Options or Convertible Securities, then such record date shall be deemed to be the date of the issuance or sale of the units of Warrant Equity deemed to have been issued or sold upon the declaration of such Dividend or the making thereof or the date of the granting of such right of subscription or purchase, as the case may be.

2C.          Subdivis