Document:

EXHIBIT 4.1

                             NOTE PURCHASE AGREEMENT

      This Note Purchase Agreement (this "Agreement") is made as of April 23,
2004 (the "Closing Date") by and between Ceptor Corporation, a Delaware
corporation (the "Company"), and the persons or entities listed as investors and
set forth on Schedule 1, annexed hereto (the "Holders"), and Xechem
International, Inc., a Delaware corporation (the "Parent").

                              W I T N E S S E T H:

      WHEREAS, the Company desires to sell and issue to the Holders, and the
Holders wish to purchase from the Company $1,100,000.00 of the Company's eight
(8%) percent convertible Notes (the "Note") due October 22, 2004 (the "Maturity
Date") having the rights and privileges set forth in the Form of Note of the
Company substantially as set forth on Exhibit A annexed hereto; and

      WHEREAS, as additional consideration for the purchase of the Note, Company
has agreed to issue to the Holders 366,667 shares (the "Investor Shares") of the
Common Stock, $0.00001 per share, par value, of the Company (the "Common
Stock"), which Investor Shares shall be distributed by the Selling Agent (as
hereinafter defined) to the Note Holders pro-rata in accordance with the value
of Notes purchased hereunder by each Note Holder; and

      WHEREAS, in order to induce the Holders to purchase the Company's Note,
Parent agrees that in the event the Company defaults in the repayment of any
amount due and owing under the Note on the due date thereof, Holders may put the
Note to Parent for conversion in the total amount of such unpaid principal plus
interest outstanding on the Maturity Date, such put to be payable solely in
shares of the common stock, par value $0.00001 per share, of Parent (the
"Conversion Securities"), upon notice to Parent at a price per share equal to
the Conversion Price (as hereinafter defined).

      Now, therefore, for good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties to this Agreement
hereby agree as follows:

      1. The Funds. On the Closing Date, the Holders shall deliver to the
Company $1,100,000.00 in cash (the "Funds") by delivery of a certified check
payable to the Company or by wire transfer to the account of the Company.

      Viewtrade Financial (the "Selling Agent") has served as selling agent with
respect to the offer and sale of the Notes. As compensation for the Selling
Agent's services hereunder, the Company shall pay to Selling Agent in cash a
selling commission ("Commission") upon each Closing, in an amount equal to ten
percent (10%) of the aggregate sales price of the Notes sold through the efforts
of Selling Agent or its authorized agent. The Company shall also pay the Selling
Agent at each Closing a non-accountable expense allowance of two (2%) percent of
the aggregate sales price of each Note sold by Company through the efforts of
Selling Agent or its authorized agent.

<PAGE>

      2. The Note. On the Closing Date, the Company shall execute and deliver to
the Holders a convertible promissory note, the form of which is annexed hereto
as Exhibit A (the "Note").

      3. Representations and Warranties of the Company. The Company hereby
represents and warrants to the Holders as follows:

            (a) Organization and Standing. The Company is a corporation duly
      organized and validly existing under, and by virtue of, the laws of the
      State of Delaware and is in good standing under such laws. The Company has
      the requisite corporate power to own and operate its properties and
      assets, and to carry on its business as presently conducted and as
      proposed to be conducted.

            (b) No Conflict. This Agreement does not: (i) conflict with any
      provision of the Company's Certificate of Incorporation or Bylaws, both as
      amended to date; or (ii) conflict with, or constitute a default (or an
      event which with notice or lapse of time or both would become a default)
      under, or give to others any rights of termination, amendment,
      acceleration or cancellation of, any agreement, indenture, patent, patent
      license or instrument to which the Company is a party (collectively,
      "Company Agreements"); or (iii) result in a violation of any federal,
      state, local or foreign law, rule, regulation, order, judgment or decree
      (including Federal and state securities laws and regulations) applicable
      to the Company or by which any property or asset of the Company is bound
      or affected.

            (c) Authorization. The execution, delivery and performance of this
      Agreement by the Company has been duly authorized by all requisite
      corporate action, and constitutes the valid and binding obligations of the
      Company enforceable in accordance with its terms, subject as to
      enforcement of remedies to applicable bankruptcy, insolvency,
      reorganization, or similar laws relating to or affecting the enforcement
      of creditors' rights.

            (d) Capitalization. The authorized capital stock of the Company
      consists of 1,000 shares of Common Stock held by Parent. Immediately
      following the date hereof, Company shall amend its Certificate of
      Incorporation and split its stock following which the Company shall have
      authorized for issuance 50,000,000 shares of capital consisting of
      40,000,000 of Common Stock, par value $0.00001 per share, and 10,000,000
      Preferred Stock, of which 3,000,000 shall be issued and outstanding shares
      of common stock held by Parent and 2,333,333 shall be shares of common
      subject to a fully vested option in favor of the management group of the
      Company to be exercised following the date hereof, with such restrictions,
      and subject to such conditions on exercise and/or forfeiture or transfer,
      as are determined by the Board of Directors of the Company. In addition,
      the Company will following the date hereof, adopt an incentive plan for
      employees and others under which there will be reserved for issuance
      fifteen (15%) percent of the issued and outstanding fully-diluted common
      stock of the Company to be issued from time to time. Company agrees not to
      grant any options to William Pursley from the aforesaid incentive plan for
      a period of twelve (12) months from the date hereof.

                                       1
<PAGE>

            (e) Common Shares. The Investor Shares are, and the Conversion
      Securities, when issued, will be, validly issued, fully-paid and
      non-assessable, free and clear of any and all liens, claims and
      encumbrances. The Conversion Securities will be reserved for issuance by
      Parent, based upon a conversion price of $0.07 per share.

            (f) No Undisclosed Liabilities. Except for a note due December 31,
      2005 payable to Marge Chassman, Trustee in the original face amount of
      $250,000 and a note due December 31, 2005 payable to Claire Strauss,
      Trustee, in the original face amount of $125,000 (the current outstanding
      balances of which are set forth in the books and records of the Company),
      the Company has no material liabilities or obligations not disclosed to
      Holders, other than those liabilities incurred in the ordinary course of
      the Company's business since December 31, 2003.

            (g) Brokers. Neither Holders, Company nor Parent has taken any
      action which would give rise to any claim by any person for brokerage
      commissions, finder's fees or similar payments by the Company, Parent or
      Holders relating to this Agreement or the transactions contemplated
      hereby.

      4. Representations and Warranties of the Holders. The Holders represent
and warrants to the Company as of the Closing Date and upon conversion of the
Note as follows (the Note and the securities issuable upon conversion of the
Note are collectively referred to as the "Securities"):

            (a) All action on the part of the Holders for the authorization,
      execution, delivery and performance by the Holders of this Agreement has
      been taken, and this Agreement constitutes a valid and binding obligation
      of the Holders, enforceable in accordance with its terms, except as may be
      limited by applicable bankruptcy, insolvency, reorganization, or similar
      laws relating to or affecting the enforcement of creditors' rights.

            (b) The Holders are acquiring the Securities for investment for
      their own account and not with a view to, or for resale in connection
      with, any distribution. The Holders understand that the Securities to be
      acquired have not been registered under the Securities Act of 1933, as
      amended (the "Act"), by reason of a specific exemption from the
      registration provisions of the Act which depends upon, among other things,
      the bona fide nature of the investment intent as expressed herein.

            (c) The Holders represent that except as otherwise disclosed to the
      Company, in writing, prior to the Holders' execution of this Agreement,
      the Holders are each an Accredited Investor, as defined in Rule 501
      promulgated under the Act. The Holders also represent the Holders have not
      been organized for the purpose of acquiring the Securities.

            (d) The Holders are experienced in evaluating and investing in
      securities of companies similarly situated to the Company, and acknowledge
      that they are able to fend for themselves, can bear the economic risk of
      an investment in the Securities, and have such knowledge and experience in
      financial or business matters that they are capable of evaluating the
      merits and risks of the investment in the Securities.

                                       2
<PAGE>

            (e) The Holders believe they have received all the information they
      consider necessary or appropriate for deciding whether to purchase the
      Securities. The Holders further represent that such Holders have had an
      opportunity to ask questions and receive answers from the Company
      regarding the terms and conditions of the offering of the Securities and
      the business, properties, prospects and financial condition of the
      Company.

            (f) The Holders acknowledge that the Securities must be held
      indefinitely unless subsequently registered under the Act or unless an
      exemption from such registration is available. The Holders are aware of
      the provisions of Rule 144 promulgated under the Act which permits limited
      resale of securities purchased in a private placement subject to the
      satisfaction of certain conditions, including, unless the Holders are an
      affiliate of the Company, among other things, the availability of certain
      current public information about the Company, the resale occurring not
      less than one year after a party has purchased and paid for the securities
      to be sold, the sale being through a "broker's transaction" or in
      transactions directly with a "market maker," and the number of shares
      being sold during any three-month period not exceeding specified
      limitations.

            (g) The Holders hereby represent that the Holders have satisfied
      themselves as to the full observance of the laws of the Holders'
      jurisdiction in connection with any invitation to subscribe for the
      Securities or any use of this Agreement, including: (i) the legal
      requirements within the Holders' jurisdiction for the purchase of the
      Securities; (ii) any foreign exchange restrictions applicable to such
      purchase; (iii) any governmental or other consents that may need to be
      obtained; and (iv) the income tax and other tax consequences, if any, that
      may be relevant to the purchase, holding, redemption, conversion, sale, or
      transfer of the Securities. The Holders' subscription and payment for, and
      the Holders' continued beneficial ownership of the Securities, will not
      violate any applicable securities or other laws of the Holders'
      jurisdiction. The Holders understand and agree that it (and not the
      Company) shall be responsible for its own tax liability that may arise as
      a result of this investment or the transactions contemplated by this
      Agreement

      5. Legends. All certificates representing any shares of the capital stock
of the Parent issuable upon conversion of the Note shall have endorsed thereon a
legend substantially as follows:

      "THESE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF
      1933. THEY MAY NOT BE SOLD, OFFERED FOR SALE, PLEDGED OR HYPOTHECATED IN
      THE ABSENCE OF AN EFFECTIVE REGISTRATION STATEMENT AS TO THE SECURITIES
      UNDER SAID ACT OR AN OPINION OF COUNSEL SATISFACTORY TO THE COMPANY THAT
      SUCH REGISTRATION IS NOT REQUIRED."

      6. Filing of Registration Statement. Upon demand by Holders given
following issuance by Parent of any amount in excess of $250,000 of Conversion
Securities and declaration of a default with respect to the Note and failure to
cure the same within forty-eight hours, Parent shall prepare, and, as soon as
practicable (a) file a registration statement with respect to the resale by
Holders (or any transferee or assignee from Holders) of the Conversion
Securities and shall include therein such number of shares of Conversion
Securities as the Notes shall be convertible at the time of such registration
(the "Registrable Securities") (the "Registration Statement"). Parent agrees
that it shall file within thirty (30) days of demand and declaration of a
default with respect to the Note and failure to cure the same within forty-eight
hours, and shall use its best efforts to cause to be declared effective a
Registration Statement for all Registrable Securities by SEC no later than
one-hundred and eighty (180) days from filing date. In the event either of these
periods shall not be met, Parent shall pay a cash penalty of two (2%) percent
per month for each month that the Registration shall not be declared effective,
or filed. In the event the Registration Statement has not been declared
effective or filed within the periods set forth above, the Note Holders shall
have the option at any time to force repayment of all of the outstanding
principal and/or interest under the Note at a sum equal to 100% of the
outstanding principal and/or interest balance then due.

                                       3
<PAGE>

            (a) Registration Procedures. The Registration Statement shall be
      filed pursuant to the procedures set forth below:

                  (i) The Parent shall use its best efforts to cause the
            Registration Statement to be filed and to become effective as soon
            as possible after it is filed, and remain continuously effective,
            until the earlier of (i) all of the Registrable Securities covered
            by such Registration Statement have been sold in accordance with the
            intended methods of disposition of the sellers set forth in such
            Registration Statement and (ii) two hundred seventy (270) days after
            such Registration Statement has been declared effective provided,
            that if for any portion of such period the Registration Statement is
            not effective, then such requirement for maintaining the
            effectiveness of the Registration Statement shall be extended by the
            length of such interruption(s), and the Parent shall prepare and
            file with the SEC such amendments to such Registration Statement and
            supplements to the prospectus contained therein as may be necessary
            to keep such Registration Statement effective and such Registration
            Statement and prospectus accurate and complete during such period.
            In the event the Registration Statement has not been declared
            effective or filed within the periods set forth above, Parent shall
            have the option at any time to repay all of the outstanding
            principal and or interest under the Note.

                  (ii) The Parent shall notify the sellers participating in such
            registration, promptly after it shall receive notice thereof, of the
            date and time when such Registration Statement and each
            post-effective amendment thereto has become effective or a
            supplement to any prospectus forming a part of such Registration
            Statement has been filed;

                  (iii) The Parent shall furnish to the sellers participating in
            such registration such reasonable number of copies of the
            Registration Statement and prospectus and such other documents as
            the sellers may reasonably request in order to facilitate the public
            offering of the Registrable Securities;

                  (iv) The Parent shall use its best efforts to register or
            qualify the Registrable Securities covered by such Registration
            Statement under such state securities or blue sky laws of such
            jurisdictions as the sellers participating in such registration may
            reasonably request, provided, however, that the Parent shall not be
            obligated to file any general consent to service of process or to
            qualify as a foreign corporation in any jurisdiction in which it is
            not so qualified or to subject itself to taxation in connection with
            any such registration or qualification of such securities;

                                       4
<PAGE>

                  (v) The Parent shall notify the sellers participating in such
            registration promptly of any request by the SEC for the amending or
            supplementing of such Registration Statement or prospectus or for
            additional information;

                  (vi) The Parent shall prepare and file with the SEC, promptly
            upon the request of any seller participating in such registration,
            the Registration Statement and any amendments or supplements to such
            Registration Statement or prospectus which, in the reasonable
            opinion of counsel for the sellers is required under the Securities
            Act or the rules and regulations thereunder in connection with the
            distribution of the Registrable Securities by the sellers or to
            otherwise comply with the requirements of the Securities Act and
            such rules and regulations;

                  (vii) The Parent shall prepare and promptly file with the SEC
            and promptly notify the sellers participating in such registration
            of the filing of such amendments or supplements to such Registration
            Statement or prospectus as may be necessary to correct any
            statements or omissions if, at the time when a prospectus relating
            to the Registrable Securities is required to be delivered under the
            Securities Act, any event has occurred as the result of which any
            such prospectus or any other prospectus then in effect may include
            an 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 not misleading. The Parent shall make available
            to the sellers and to the underwriters any such supplement or
            amendment. The sellers participating in such registration agree
            that, upon receipt of any notice from the Parent of the occurrence
            of any event of the kind described in this Section 6(a)(vii), the
            sellers will forthwith discontinue the offer and sale of Registrable
            Securities pursuant to the Registration Statement covering such
            Registrable Securities until receipt by the sellers and underwriters
            of the copies of such supplemented or amended prospectus and, if so
            directed by the Parent, the sellers will deliver to the Parent all
            copies, other than permanent file copies then in the sellers'
            possession, of the most recent prospectus covering such Registrable
            Securities at the time of receipt of such notice. In the event the
            Parent shall give such notice, the Parent shall extend the period
            during which such Registration Statement shall be maintained
            effective as provided in Section 6.2(a) hereof by the number of days
            during the period from and including the date of the giving of such
            notice to the date when the Company shall make available to the
            sellers such supplemented or amended prospectus;

                                       5
<PAGE>

                  (viii) The Parent shall advise the sellers participating in
            such registration, promptly after it shall receive notice or obtain
            knowledge thereof, of the issuance of any stop order by the SEC
            suspending the effectiveness of such Registration Statement or the
            initiation or threatening of any proceeding for that purpose and
            promptly use its best efforts to prevent the issuance of any stop
            order or to obtain its withdrawal if such stop order should be
            issued;

                  (ix) The Parent shall otherwise use its best efforts to comply
            with all applicable rules and regulations of the SEC, and make
            generally available to the Parent's security Holders' earnings
            statements satisfying the provisions of Section 11(a) of the
            Securities Act, no later than forty-five (45) days after the end of
            any twelve (12) month period (or ninety (90) days, if such a period
            is a fiscal year) beginning with the first month of the Parent's
            first fiscal quarter commencing after the effective date of the
            Registration Statement;

                  (x) The Parent shall not file any amendment or supplement to
            the Registration Statement or prospectus to which a majority in
            interest of the sellers participating in such registration has
            objected on the grounds that such amendment or supplement does not
            comply in all material respects with the requirements of the
            Securities Act or the rules and regulations thereunder, after having
            been furnished with a copy thereof at least three business days
            prior to the filing thereof unless the Parent shall have obtained an
            opinion of counsel that such amendment is required under the
            Securities Act or the rules or regulations adopted thereunder in
            connection with the distribution of Registrable Securities by the
            sellers.

                  (xi) The Parent may, at its option, register additional shares
            of Parent common stock in the Registration Statement for sale by
            other Holders of its Common Stock or include the Registrable
            Securities in a registration in which shares of its Common Stock are
            sold to an underwriter for reoffering to the public (an
            "Underwritten Offering").

            (b) Expenses of Registration.

                  (i) All expenses of the Parent incident to the Parent's
            performance of or compliance with the provisions of this Section 6
            shall be borne by the Parent including without limitation:

                  (ii) All registration and filing fees;

                  (iii) Fees and expenses of compliance with all securities or
            blue sky laws (including fees and disbursements of counsel for the
            Parent in connection with blue sky qualifications of the Registrable
            Securities; provided, however, that the Parent shall not be required
            to consent to general service of process in any such state);

                  (iv) Fees and disbursements of counsel for the Parent, and
            their independent auditors.

                                       6
<PAGE>

      Nothing in this Section 6 shall be deemed to require the Parent to pay or
bear any expenses of any seller's attorneys or accountants or any other personal
expenses or any underwriting discounts relating to the Registrable Securities,
selling commissions or similar fees attributable pro rata to the Registrable
Securities if such registration results in an Underwritten Offering of all or
any portion of the Registrable Securities.

            (c) Sellers' Agreements.

                  (i) The sellers participating in such registration shall
            promptly provide all information concerning such sellers and/or the
            Seller required to be included in the Registration Statement which
            is requested by the Parent.

                  (ii) In the event any of the Registrable Securities are
            included in an underwritten offering, each seller participating in
            such registration agrees to enter into with the managing underwriter
            of such offering, and perform its obligations under: (i) an
            underwriting agreement, in usual and customary form; and (ii) a
            lock-up agreement similar in form and substance to lock-up
            agreements executed by other executive officers and directors of the
            Parent.

      Notwithstanding anything to the contrary in Section 6(b), at any time
after the Registration Statement has been declared effective, the Parent may
delay the disclosure of material, non-public information concerning the Parent
the disclosure of which at the time is not, in the good faith opinion of the
Board of Directors of the Parent and its counsel, in the best interest of the
Parent and, in the opinion of counsel to the Parent, otherwise required (a
"Grace Period"); provided, that the Parent shall promptly (i) notify the sellers
participating in such registration in writing of the existence of material,
non-public information giving rise to a Grace Period and the date on which the
Grace Period will begin, and (ii) notify the sellers in writing of the date on
which the Grace Period ends; and, provided further, that during any consecutive
three hundred and sixty-five (365) day period, there shall be only three Grace
Periods, any such Grace Period not to exceed seventy-five (75) consecutive days
in the aggregate and all Grace Periods combined not to exceed one-hundred and
eighty (180) days in the aggregate (an "Allowable Grace Period"). For purposes
of determining the length of a Grace Period above, the Grace Period shall begin
on and include the date the sellers receive the notice referred to in clause (i)
above and shall end on and include the date the sellers receive the notice
referred to in clause (ii) above. Upon expiration of the Allowable Grace Period,
the Parent shall again be bound by the first sentence of Section 6.2(g) with
respect to the information giving rise thereto.

                  (d) Exception to Filing of Registration Statement.
            Notwithstanding the provisions of this Section 6, the Parent shall
            have no further obligation to file any Registration Statement
            hereunder or maintain the effectiveness of any Registration
            Statement filed with respect to any seller in the event all of the
            Registrable Securities owned by such Seller: (i) have been
            distributed to the public pursuant to Rule 144 (or any similar
            provisions then in force) under the Securities Act: or (ii) are
            otherwise freely transferable without restriction under the
            Securities Act.

                                       7
<PAGE>

      7. General Provisions.

            (a) Governing Law. THIS AGREEMENT SHALL BE GOVERNED IN ALL RESPECTS
      BY THE LAWS OF THE STATE OF DELAWARE AS SUCH LAWS ARE APPLIED TO
      AGREEMENTS BETWEEN DELAWARE RESIDENTS ENTERED INTO AND TO BE PERFORMED
      ENTIRELY WITHIN DELAWARE.

            (b) Notices. Any notice or other communication required or permitted
      to be given hereunder shall be in writing by mail, facsimile or personal
      delivery and shall be effective upon actual receipt of such notice. The
      addresses for such communications shall be:

                        If to the Company:

                        Ceptor Corporation
                        200 International Circle
                        Suite 5100
                        Hunt Valley, Maryland  21030
                        (410) 527-9867 (fax)

                        Att: William Pursley, Chief Executive Officer,

                        With a copy to:

                        Olshan Grundman Frome Rosenzweig & Wolosky LLP
                        Park Avenue Tower
                        65 East 55th Street

                        New York, New York 10022
                        (212) 451-2222 (fax)
                        Att: Harvey J. Kesner, Esq.

                        If to the Parent:

                        Xechem International, Inc.
                        100 Jersey Avenue
                        Building B, Suite 310
                        New Brunswick, New Jersey 08901-3279

                        Att: Ramesh C. Pandey, Chief Executive Officer
                        732-247-4090 (fax)

                        With a copy to:

                        Shefsky & Froelich Ltd.
                        444 North Michigan Avenue
                        Suite 2500
                        Chicago, Illinois 60611
                        Att:  Mitch Goldsmith, Esq.
                        312-527-3194 (fax)

                                       8
<PAGE>

                        If to the Holders :

                        To such names and addresses as shall be set forth on
                        Exhibit A hereto With a copy to:

                        Blank Rome LLP
                        Bruce C. Rosetto, Esq.
                        1200 North Federal Highway
                        Suite 417
                        Boca Raton, Florida 33432
                        Att: Bruce C. Rosetto, Esq.
                        561-417-8186 (fax)

                  (c) Entire Agreement. Except as otherwise provided herein,
            this Agreement, the Note and the other documents delivered pursuant
            hereto constitute the full and entire understanding and agreement
            between the parties with regard to the subjects hereof and thereof.

                  (d) Amendment. This Agreement may only be amended, waived,
            discharged or terminated by a written instrument signed by the party
            against whom enforcement of any such amendment, waiver, discharge or
            termination is sought.

                  (e) Successors and Assigns. Except as otherwise expressly
            provided in this Agreement or the Note, the provisions of this
            Agreement and the Note shall inure to the benefit of, and be binding
            upon, the successors, assigns, heirs, executors and administrators
            of the parties hereto.

                  (f) Severability. In case any provision of this Agreement
            shall be invalid, illegal or unenforceable, the validity, legality
            and enforceability of the remaining provisions shall not in any way
            be affected or impaired thereby.

                  (g) Titles and Subtitles. The titles of the Sections of this
            Agreement are for convenience of reference only and are not to be
            considered in construing this Agreement.

                  (h) Expenses. The Company and the Holders shall each bear
            their own expenses incurred with respect to this transaction.

                  (i) Counterparts. This Agreement may be executed in any number
            of counterparts, each of which shall be an original, but all of
            which together shall be deemed to constitute one instrument.

                                       9
<PAGE>

      IN WITNESS WHEREOF, the parties have caused this agreement to be executed
by its officers thereunto duly authorized.

                                        "Company"

                                        CEPTOR CORPORATION.

                                        By:
                                           -------------------------------------
                                           Name:  William Pursley
                                           Title:   Chief Executive Officer

                                        XECHEM INTERNATIONAL, INC.

                                        By:
                                           -------------------------------------
                                           Name:
                                           Title:

                                        "Holders"

                                        By:
                                           -------------------------------------
                                           Name:
                                           Title:

                                        By:
                                           -------------------------------------
                                           Name:
                                           Title:

                                        By:
                                           -------------------------------------
                                           Name:
                                           Title:

                                       10
<PAGE>

                                   SCHEDULE 1

                                    INVESTORS

                                       11
<PAGE>

                                    EXHIBIT A

                             FORM OF PROMISSORY NOTE

                                       12EXHIBIT 4.2

THE SECURITIES REPRESENTED BY THIS INSTRUMENT HAVE NOT BEEN REGISTERED UNDER THE
SECURITIES ACT OF 1933, AS AMENDED, OR THE SECURITIES LAWS OF ANY STATE, AND MAY
NOT BE SOLD, TRANSFERRED, ASSIGNED, PLEDGED OR HYPOTHECATED UNLESS AND UNTIL
REGISTERED UNDER SUCH ACT AND/OR APPLICABLE STATE SECURITIES LAWS, OR UNLESS THE
CORPORATION HAS RECEIVED AN OPINION OF COUNSEL OR OTHER EVIDENCE, REASONABLY
SATISFACTORY TO THE CORPORATION AND ITS COUNSEL, THAT SUCH REGISTRATION IS NOT
REQUIRED.

                               CEPTOR CORPORATION

                           CONVERTIBLE PROMISSORY NOTE
                                (non-negotiable)

                                                           Hunt Valley, Maryland
$___,000.00                                                       April 23, 2004

      FOR VALUE RECEIVED Ceptor Corporation, a Delaware corporation (the
"Company"), promises to pay to _________________, a ______ corporation (the
"Holder"), at the office of the Holder, the principal amount of __________
thousand dollars and No/100ths ($___,000.00), or such lesser amount as shall
equal the outstanding principal amount hereof, together with simple interest
from the date of this Note on the unpaid principal balance at a rate equal to
eight (8%) percent per annum, computed on the basis of the actual number of days
elapsed and a year of 365 days. All unpaid principal, together with any then
accrued but unpaid interest and any other amounts payable hereunder, shall be
due and payable on the earlier of (i) the Next Financing (as hereinafter
defined) or (ii) October 22, 2004 (the "Maturity Date").

      The following is a statement of the rights of the Holder of this Note and
the conditions to which this Note is subject, and to which the Holder, by the
acceptance of this Note, agrees:

      1. Certain Definitions.

            (a) "Conversion Securities" means the shares of common stock, par
      value $0.00001 per share (the "Common Stock"), of Xechem International,
      Inc (the "Parent") with such rights, preferences, privileges and
      restrictions, contractual or otherwise, as the set forth in the
      Certificate of Incorporation and bylaws of Parent.

            (b) "Conversion Price" means the lesser of (i) seven cents ($0.07)
      per share, or (ii) seventy-five (75%) percent of the Market Price of the
      Conversion Securities on the Conversion Date.

            (c) "Default" means:

                  i) the Company shall default in the payment of interest and/or
            principal on this Note (subject to the right of the Holder to
            convert all of the presently due and outstanding principal and/or
            interest owing under this Note into Conversion Securities upon which
            this Note shall not be deemed in Default) and such default shall
            continue for ten (10) business days after the due date thereof; or

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<PAGE>

                  ii) any of the representations or warranties made by the
            Company or Parent herein or in any certificate or financial or other
            statements heretofore or hereafter furnished by or on behalf of
            Parent or the Company to Holder in connection with the execution and
            delivery of this Note or such other documents shall be false or
            misleading in any material respect at the time made; or

                  iii) Parent or the Company shall fail to materially perform or
            observe any covenant or agreement in the Note Purchase Agreement, or
            any other covenant, term, provision, condition, agreement or
            obligation of Parent or the Company under this Note and such failure
            shall continue uncured for a period of ten (10) business days after
            notice from the Holder of such failure; or

                  iv) the Company shall (1) become insolvent; (2) admit in
            writing its inability to pay its debts generally as they mature; (3)
            make an assignment for the benefit of creditors or commence
            proceedings for its dissolution; or (4) apply for or consent to the
            appointment of a trustee, liquidator or receiver for it or for a
            substantial part of its property or business; or

                  v) a trustee, liquidator or receiver shall be appointed for
            the Company or for a substantial part of its property or business
            without its consent and shall not be discharged within thirty (30)
            days after such appointment; or

                  vi) any governmental agency or any court of competent
            jurisdiction at the insistance of any governmental agency shall
            assume custody or control of the whole or any substantial portion of
            the properties or assets of the Company and shall not be dismissed
            within thirty (30) days thereafter; or

                  vii) the Company shall sell or otherwise transfer all or
            substantially all of its assets; or

                  viii) bankruptcy, reorganization, insolvency or liquidation
            proceedings or other proceedings, or relief under any bankruptcy law
            or any law for the relief of debt shall be instituted by or against
            the Company and, if instituted against the Company shall not be
            dismissed within thirty (30) days after such institution, or the
            Company shall by any action or answer approve of, consent to, or
            acquiesce in any such proceedings or admit to any material
            allegations of, or default in answering a petition filed in any such
            proceeding; or

                  ix) the Company shall be in default of any of its
            indebtedness, including but not limited to its senior lending
            facility, and the holders thereof shall have accelerated such
            indebtedness; or

                  x) the Company shall be in material default of any of its
            indebtedness that gives the holder thereof the right to accelerate
            such indebtedness.

                                       14
<PAGE>

            (d) "Next Financing" means the next transaction (or series of
      related transactions) after the date of this Note in which the Company
      issues and sells shares of its capital stock in exchange for aggregate
      gross proceeds of at least $1.0 million (including any amounts received
      upon conversion or cancellation of indebtedness).

            (e) "Market Price" means the price per share of the Conversion
      Securities determined as follows:

                  i) If the Conversion Securities are listed on NASDAQ, the
            average closing bid price for the ten Trading Days immediately
            preceding the date of valuation;

                  ii) If the Conversion Securities are listed on the New York
            Stock Exchange or the American Stock Exchange, the average closing
            bid price for the ten Trading Days immediately preceding the date of
            valuation;

                  iii) If neither (i) nor (ii) apply but the Conversion
            Securities are quoted in the over-the-counter market, another
            recognized exchange, on the pink sheets or bulletin board, the
            lesser of (A) the last sales price or (B) the mean between the last
            reported "bid" and "asked" prices thereof in each case, for the ten
            Trading Days immediately preceding valuation; and

                  iv) If neither clause (i), (ii) or (iii) above applies, the
            market value as determined by a nationally recognized investment
            banking firm or other nationally recognized financial advisor
            retained by the Parent for such purpose, taking into consideration,
            among other factors, the earnings history, book value and prospects
            for the Parent, and the prices at which shares of Conversion
            Securities recently have been traded. Such determination shall be
            conclusive and binding on all persons.

      During any period in which a Market Price shall be used to determine a
Conversion Price, Holder agrees that neither Holder nor any person or entity
controlling, controlled by or under common control with Holder shall enter or
place any short transaction orders in the Conversion Securities.

      2. Prepayment. The Company may prepay this Note at any time, in whole or
in part, provided any such prepayment will be applied first to the payment of
expenses due under this Note, second to interest accrued on this Note and third,
if the amount of prepayment exceeds the amount of all such expenses and accrued
interest, to the payment of principal of this Note.

      3. Conversion at the Option of the Holder. The Holder of this Note shall
have the following conversion rights.

            (a) Holder's Right to Convert. This Note shall be convertible, in
      whole or in part, at any time following delivery of notice to the Company
      and Parent (at the address and in the manner set forth in the Note
      Purchase Agreement pursuant to which this form of Note is attached as
      Exhibit A) of the existence of a Default under the Note, not cured within
      48 hours thereof at the option of the Holder hereof, into fully paid,
      validly issued and nonassessable shares of the Conversion Securities. If
      this Note is converted in part, the remaining portion of this Note not so
      converted shall remain entitled to the conversion rights provided herein.

                                       15
<PAGE>

            (b) Conversion Price for Holder Converted Shares. The Outstanding
      Principal Amount of this Note and interest that is converted into
      Conversion Securities at the option of the Holder shall be convertible at
      the Conversion Price.

            (c) Mechanics of Conversion. In order to convert this Note (in whole
      or in part) into full Conversion Securities, the Holder (i) shall give
      written notice in the form of EXHIBIT 1 hereto (the "Conversion Notice")
      by facsimile to the Company and the Parent at such office that the Holder
      elects to convert the principal amount (plus accrued but unpaid interest
      and default payments) specified therein, which such notice and election
      shall be revocable by the Holder at any time prior to its receipt of the
      Conversion Securities upon conversion, and (ii) as soon as practicable
      after such notice, shall surrender this Note, duly endorsed, by either
      overnight courier or 2-day courier, to the principal office of the Parent;
      provided, however, that the Parent shall not be obligated to issue
      certificates evidencing the shares of the Conversion Securities issuable
      upon such conversion unless either the Note evidencing the principal
      amount is delivered to the Parent as provided above, or the Holder
      notifies the Parent that such Note(s) have been lost, stolen or destroyed
      and promptly executes an agreement reasonably satisfactory to the Parent
      to indemnify the Parent from any loss incurred by it in connection with
      such lost, stolen or destroyed Notes. If a Holder is converting less than
      the maximum number of shares it may convert under its Note, the Company
      shall, upon notice received from Holder and Parent of such facts with
      documentary copies of all notices, Conversion Securities issued, and
      cancelled notes, shall reissue the Note with the appropriate remaining
      principal amount as soon as practicable after the Parent shall have
      received the Holder's surrendered Note and the Company has received copies
      of all documents to its satisfaction.

      The Parent shall issue and deliver within one business day of the delivery
to the Parent of such Conversion Notice, to such Holder of Note(s) at the
address of the Holder, or to its designee, a certificate or certificates for the
number of shares of Conversion Securities to which the Holder shall be entitled
as aforesaid, together with a calculation of the Conversion Price and a Note for
the principal amount not submitted for conversion. The date on which the
Conversion Notice is given (the "Holder Conversion Date") shall be deemed to be
the date the Parent received by facsimile the Conversion Notice, and the person
or persons entitled to receive the Conversion Securities issuable upon such
conversion shall be treated for all purposes as the record holder or holders of
such shares of Conversion Securities on such date.

      In lieu of delivering physical certificates representing the Conversion
Securities issuable upon conversion of Notes, provided the Company's transfer
agent is participating in the Depository Trust Company ("DTC") Fast Automated
Securities Transfer ("FAST") program, upon request of the Holder, the Parent
shall use its best efforts to cause its transfer agent to electronically
transmit the Conversion Securities issuable upon conversion or exercise to the
Holder, by crediting the account of Holder's prime broker with DTC through its
Deposit Withdrawal Agent Commission ("DWAC") system. The time periods for
delivery described above shall apply to the electronic transmittals through the
DWAC system. The parties agree to coordinate with DTC to accomplish this
objective. The conversions shall be deemed to have been made immediately prior
to the close of business on the Holder Conversion Date. The person or persons
entitled to receive the Conversion Securities issuable upon such conversion
shall be treated for all purposes as the record holder or holders of such
Conversion Securities at the close of business on the Holder Conversion Date.

                                       16
<PAGE>

            (d) Limitations on Right to Convert. In no event shall the Holder be
      permitted to convert this Note in excess of that amount upon the
      Conversion of which the number of Conversion Securities to be issued
      pursuant to such Conversion, when added to the number of shares of
      Conversion Securities issued pursuant to all prior Conversions of the
      Note, would exceed 19.99% of the number of shares of Parent common stock
      outstanding on the Closing Date (subject to equitable adjustment from time
      to time for the events described below) (the "Cap Amount"), except that
      such limitation shall not apply in the event that Parent obtains the
      approval of the holders of a majority of the Parent's outstanding common
      stock ("Stockholder Approval") for the issuance of Conversion Securities
      in excess of the Cap Amount.

      In the event that Stockholder Approval shall be required for the issuance
of Conversion Shares in excess of the Cap Amount, Parent may elect to prepay
this Note in full after which neither Parent nor Company shall have any further
obligation with respect thereto. In the event Parent does not repay this Note in
full within two (2) business days of receipt of a Conversion Notice that
requires Stockholder Approval, Parent shall use its reasonable best efforts to
effect Stockholder Approval of the Conversion within sixty (60) days of receipt
of such Conversion Notice. Parent may at any time prior to the receipt of
Stockholder Approval, repay all of the outstanding principal and or interest
under the Note or such amount as will then result in a Conversion below the Cap
Amount, instead of obtaining a required Stockholder Approval of the Conversion.
In the event the Stockholder Approval has not been obtained within the timeframe
set forth and Parent has not repaid the Note, the Note Holders shall have the
option at any time to force Parent's repayment of all of the outstanding
principal and/or interest under the Note at a sum equal to 100% of the
outstanding principal and/or interest balance then due.

      In the event Holder has given a Conversion Notice, such put into
Conversion Securities, or conversion right, shall be available to Holder for a
period of thirty (30) days following the date of the Conversion Notice following
which thirty (30) day period no further conversion of the Note into Conversion
Securities shall be permitted.

            (e) Fractional Shares; Interest; Nonassessable; Effect of
      Conversion. Any fractional shares to be issued upon conversion of this
      Note shall be rounded to the nearest whole share. The Parent covenants
      that the shares of Conversion Securities issuable upon the conversion of
      this Note will, upon conversion of this Note, be validly issued, fully
      paid and nonassessable and free from all taxes, liens and charges in
      respect of the issue thereof. Upon conversion of this Note in full and the
      payment of the amounts specified in this Section 3, the Company and Parent
      shall be forever released from all their respective obligations and
      liabilities under this Note, although the obligations under the Note
      Purchase Agreement of which this Note is a part, shall survive.

                                       17
<PAGE>

            (f) Further Assurances. In connection with the conversion of this
      Note, the Holder, by acceptance of this Note, agrees to execute all
      agreements and other documents executed by the investors in the Next
      Financing.

      4. Miscellaneous.

            (a) Loss, Theft, Destruction or Mutilation of Note. Upon receipt of
      evidence reasonably satisfactory to the Company of the loss, theft,
      destruction or mutilation of this Note and, in the case of loss, theft or
      destruction, delivery of an indemnity agreement reasonably satisfactory in
      form and substance to the Company or, in the case of mutilation, on
      surrender and cancellation of this Note, the Company shall execute and
      deliver, in lieu of this Note, a new Note executed in the same manner as
      this Note, in the same principal amount as the unpaid principal amount of
      this Note and dated the date to which interest shall have been paid on
      this Note or, if no interest shall have yet been so paid, dated the date
      of this Note.

            (b) Payment. All payments under this Note shall be made in lawful
      tender of the United States.

            (c) Waivers. The Company hereby waives notice of default,
      presentment or demand for payment, protest or notice of nonpayment or
      dishonor and all other notices or demands relative to this instrument.

            (d) Usury. In the event that any interest paid on this Note is
      deemed to be in excess of the then legal maximum rate, then that portion
      of the interest payment representing an amount in excess of the then legal
      maximum rate shall be deemed a payment of principal and applied against
      the principal of this Note.

            (e) Waiver and Amendment. Any provision of this Note may be amended,
      waived or modified only by an instrument in writing signed by the party
      against which enforcement of the same is sought.

            (f) Notices. Any notice, request or other communication required or
      permitted hereunder shall be given in accordance with the Note Purchase
      Agreement.

            (g) Expenses; Attorneys' Fees. If action is instituted to collect
      this Note, the Company promises to pay all reasonable costs and expenses,
      including, without limitation, reasonable attorneys' fees and costs,
      incurred in connection with such action.

            (h) Successors and Assigns. This Note may be assigned or transferred
      by the Holder only with the prior written approval of the Company. Subject
      to the preceding sentence, the rights and obligations of the Company and
      the Holder of this Note shall be binding upon and benefit the successors,
      assigns, heirs, administrators and transferees of the parties. The Company
      shall maintain a registry, in accordance with U.S. Treasury Regulation
      Section 5f.103-1(c)(1) and (2), evidencing its obligation to pay principal
      and interest to the Holder pursuant to this Note. Such registry shall
      represent the record of ownership and right to receive principal and
      interest pursuant to this Note. A transfer of the right to receive
      principal and interest under this Note shall be transferable only through
      an appropriate entry in the registry.

                                       18
<PAGE>

            (i) Governing Law. THIS NOTE SHALL BE GOVERNED IN ALL RESPECTS BY
      THE LAWS OF THE STATE OF DELAWARE AS SUCH LAWS ARE APPLIED TO AGREEMENTS
      BETWEEN DELAWARE RESIDENTS ENTERED INTO AND TO BE PERFORMED ENTIRELY
      WITHIN DELAWARE.

      IN WITNESS WHEREOF, the Company has caused this Note to be executed by its
officers thereunto duly authorized.

                                        CEPTOR CORPORATION.

                                        By:
                                           -------------------------------------
                                        Name:  William Pursley
                                        Title: Chief Executive Officer

                                        XECHEM INTERNATIONAL, INC.

                                        By:
                                           -------------------------------------
                                        Name:
                                        Title:

                                       19

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