EXHIBIT 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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                  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.


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<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.


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            (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.


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            (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.


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            (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.


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            (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:


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