EXHIBIT 4.3

                           WAIVER OF RIGHTS UNDER NOTE

      The undersigned holders of Notes of Ceptor Corporation are party to a
certain Note Agreement (the "Note") and Note Purchase Agreement ("Purchase
Agreement") by and among Ceptor Corporation, Xechem International, Inc. and
certain other parties signatory to the Purchase Agreement dated as of the date
hereof. Terms not otherwise defined herein shall have the meanings ascribed to
such terms in the Purchase Agreement.

      1.    Each undersigned Holder agrees that in the event of any of Holder's
            Note is converted into the Conversion Securities and not registered
            within the time periods set forth under Section 6 of the Purchase
            Agreement, Holder waives any and all right to require repayment by
            Parent in cash of all or any portion of the Note by Parent. Holder
            further agrees that this waiver shall be binding upon any successor
            in interest to Holder's Note or any portion thereof or Parent's
            guarantee of Ceptor's obligation under said Note, and Holder shall
            notify each successor in interest of the same and obtain a signed
            acknowledgement thereof; if for whatever reason a successor in
            interest to Holder's Note or of Parent's guarantee thereof
            nonetheless seeks or obtains payment in cash by Parent with respect
            to said Note (other than by Parent's election), then Holder shall
            indemnify and hold harmless Parent from and against any and all
            liability Parent may incur as a result of such action.

      2.    Each undersigned Holder agrees that in the event of any of Holder's
            Note is converted into the Conversion Securities as a result of
            Parent's election to convert the Note into Conversion Securities,
            and undersigned Holder thereupon pursuant to Section 3(d) of the
            Note obtains the right to receive Conversion Securities, Holder
            waives any and all right to require repayment by Parent in cash of
            all or any portion of the Note by Parent. Holder further agrees that
            this waiver shall be binding upon any successor in interest to
            Holder's Note or any portion thereof or Parent's guarantee of
            Ceptor's obligation under said Note, and Holder shall notify each
            successor in interest of the same and obtain a signed
            acknowledgement thereof; if for whatever reason a successor in
            interest to Holder's Note or of Parent's guarantee thereof
            nonetheless seeks or obtains payment in cash by Parent with respect
            to said Note (other than by Parent's election), then Holder shall
            indemnify and hold harmless Parent from and against any and all
            liability Parent may incur as a result of such action.

      3.    Parent shall be permitted to make any election permitted in the
            Purchase Agreement to be made by Parent individually with respect to
            Holders separately, and shall not be required to elect with respect
            to all Holders, generally.

      4.    Each undersigned Holder agrees that in the event such Holder
            delivers a Conversion Notice in the manner and as described in the
            Note following the default, such Holder shall look solely to the
            Conversion Securities into which the Note is Convertible in the
            event of any Default under the Note.


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      5.    Holder further acknowledges, and Parent and William Pursley ("WP")
            each agree, that Parent has entered into an agreement with WP
            granting certain options to acquire shares of common stock of Parent
            and agreed to make available to Parent pursuant thereto 43,000,000
            shares of common stock of Parent. WP has agreed with respect to the
            undersigned Holders and their successors or assigns, that in the
            event that any Conversion Securities are required to be issued under
            the Purchase Agreement or the Note, to make available to Parent by
            way of setoff, such number of shares of the 43,000,000 shares of
            common stock option of Parent subject to the foregoing agreement as
            are necessary to satisfy the obligation of Parent to issue to the
            undersigned Holders Conversion Securities (i.e., shares of common
            stock of Parent) upon conversion of any Note held by any undersigned
            Holder; each Holder acknowledges that Parent shall be under no
            obligation to issue new shares to any undersigned Holder party to
            this Waiver to satisfy any obligation with respect to the Note or
            Parent's guarantee thereof other than those shares that are subject
            to the setoff against WP options, and WP agrees to exercise such
            Options in the event that Conversion Securities are required to be
            delivered hereunder. Parent acknowledges that the option is fully
            vested for these purposes.

      6.    Each undersigned Holder is also party to a Merger Agreement dated as
            of December 23, 2003 by and between Parent, Ceptor Acquisition,
            Inc., and Ceptor Corporation pursuant to which, in Section 1.7
            thereof, the undersigned are entitled to payment of certain
            Contingent Consideration upon the occurrence of certain Award
            Events, as such terms are defined in the Merger Agreement. Each of
            the undersigned represent and warrant that they have not pledged or
            assigned their right to the Contingent Consideration to which they
            may become entitled and hereby waive and release Parent from any and
            all obligation with respect to payment of the Contingent
            Consideration on the basis of the representation of Ceptor to
            provide the undersigned with reasonably equivalent benefits,
            provided, however, that such benefits shall be payable in shares of
            the common stock of Ceptor, and that such release of Parent is not
            conditioned upon Ceptor's provision of such replacement benefits or
            that the undersigned shall be satisfied with the terms and
            conditions or value thereof.


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                                        HOLDERS:

Date:______                             By:_____________________________________
                                        Name:
                                        Title:

Date:______                             By:_____________________________________
                                        Name:
                                        Title:

AGREED WITH RESPECT TO PARAGRAPH 5 AND 6 ONLY:

_________________________________
William Pursley


XECHEM INTERNATIONAL, INC.


By:_______________________________
Name:
Title:


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