Document:

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                                                                 EXHIBIT 10.34.1

          AMENDMENT TO THE FACILITY SET-UP AND CONTRACT MANUFACTURING
                       AGREEMENT AND THE LICENSE AGREEMENT

                                     between

                            RMS Medical Systems Inc.
                                 hereafter "RMS"
                   located at 13700 Alton Parkway, Suite 160,
                        in Irvine, California, 92618, USA

                                       and

                BEBIG Isotopentechnik und Umweltdiagnostik GmbH,
                                hereafter "BEBIG"
                        located at Robert-Rossle-Str.10,
                           in D-13125 Berlin, Germany

BACKGROUND

RMS and BEBIG have signed a FACILITY SET-UP AND CONTRACT MANUFACTURING AGREEMENT
including the ADDENDUM TO FACILITY SET-UP AND CONTRACT MANUFACTURING AGREEMENT
AND A LICENSE AGREEMENT to cooperate in the production of radioactive balloon
catheters in July 28, 1999.

In the mean time the originally designed manufacturing process and its
production capacity, being the basis for the above mentioned agreements, has
changed. Additional research and development work has been and will be necessary
as well, that has not been provided for in the above mentioned agreements.

In light of the above, both parties desire to amend the existing FACILITY SET-UP
AND CONTRACT MANUFACTURING AGREEMENT including the ADDENDUM TO FACILITY SET-UP
AND CONTRACT MANUFACTURING AGREEMENT and the LICENSE AGREEMENT.

1.   NEW RESOURCE REQUIREMENTS FOR HIGH PRODUCTION CAPACITY PROCESS.

     BEBIG will use its best efforts to install a new high production capacity
     line with a maximum of 200 activity carriers per week at its Berlin
     facility in accordance with the tasks and timetable set forth in Schedule A
     and Appendix 1 to this amendment. Such activity will require NEW RESOURCE
     REQUIREMENTS consisting of the items "Additional Equipment", "Development
     Component", and "Validation". A further breakdown of these items is shown
     in Appendix 1 of this amendment.

     Both parties agree that for the new resource requirements RMS will
     compensate BEBIG or its affiliates per Schedule A with an investment
     contribution of US $ 686,000 excluding taxes if any.

     Schedule A of this amendment shows payments that are still due to BEBIG by
     RMS for the completion of this project. These include original payments
     from the FACILITY SET-UP AND CONTRACT MANUFACTURING AGREEMENT, the payments
     for the NEW

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     RESOURCE REQUIREMENTS, and the payment for the LOW CAPACITY PRODUCTION
     PROCESS. This shall not be interpreted as a waiver for any other costs and
     payments the parties agreed to in the above mentioned agreements including
     but not limited to payments that have already been transferred from RMS to
     BEBIG, rent of laboratory space, license fees, royalties, etc.

2.   LOW CAPACITY PRODUCTION PROCESS

     In order to be able to commence production already in the last quarter of
     the year 2000 BEBIG will use its best efforts to establish a low capacity
     production line with a maximum capacity of 20 activity carriers per week in
     parallel to the high volume capacity production at BEBIG in accordance with
     the tasks and timetable set forth in Schedule A and Appendix 1 to this
     amendment.

     Both parties agree that for these additional costs RMS will compensate
     BEBIG or its affiliates per Schedule A with an investment contribution of
     US $ 36,000 excluding taxes if any.

3.   ADDITIONAL RESEARCH AND DEVELOPMENT WORK.

     For the technique of radiolabeling with radioactive P-32, additional R&D
     work was necessary. For this R&D work RMS has compensated BEBIG's
     affiliate, IPL, with US $98,000. The parties acknowledge that the scope of
     this work was completed under the joint collaboration of BEBIG's California
     affiliate, IPL and RMS and funded exclusively by RMS. Therefore, the
     parties agree that any inventions, improvements, discoveries or other
     intellectual property developed by BEBIG or its affiliates in the course of
     such work shall be jointly owned. Both parties are unencumbered in the use
     and rights of this technology. Furthermore, BEBIG and/or its affiliates
     will assist RMS in its filing for the patent rights of the technology. The
     patent shall include the appropriate inventors from RMS and BEBIG in
     accordance with applicable patent law and designate RMS and BEBIG as
     assignees.

     4. COMPENSATIONS.

     (a) RMS will compensate BEBIG for the FACILITY SET-UP AND CONTRACT
     MANUFACTURING AGREEMENT, the NEW RESOURCE REQUIREMENTS, and the LOW
     CAPACITY PRODUCTION PROCESS per Schedule A.

5.   LICENSE FEE OFFSETS.

     Both parties agree, that the US$ 686,000, US$ 36,000, and US$ 98,000 in
     sections 1, 2, and 3 in this amendment are not subject to offsetting of the
     license fee or royalties as provided by the LICENSE AGREEMENT, Section 4.

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6.   MAINTENANCE COST OF EQUIPMENT.

     Both parties agree, that RMS covers all maintenance cost of the equipment
     delivered by RMS during the rental term. Maintenance cost on the before
     mentioned equipment is billed back to RMS at cost.

     Except as specifically modified by this amendment, all terms and conditions
     of the FACILITY SET-UP AND CONTRACT MANUFACTURING AGREEMENT and the LICENSE
     AGREEMENT shall continue unchanged.

Date:                                         Date:

---------------------------------             ----------------------------------
           BEBIG GmbH                                        RMS

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                                   Schedule A
<TABLE>
<CAPTION>

<S>                                           <C>                                   <C>
-------------------------------------------------------------------------------------------------
Milestone                                     Target Date for Completion            Amount in US$
-------------------------------------------------------------------------------------------------

Upon Execution for Delivery of                                                         585,000
Components from Radiance

Upon Execution For Additional                                                          147,000
Resources per the Amendment

Completion of Low Volume P(32)                    September 11, 2000                    30,000
Labeling Cell

Completion of Assembly Platform                   September 15, 2000                   205,000
Containment Cells

Upon Operational Readiness Following
Completion of Hot Product Validations
at Low Volumes                                     November 27, 2000                   190,000

Upon Delivery of the First RDX
Catheter Meeting Radiance's
Specifications                                     November 27, 2000                    90,000

Upon Operational Readiness Following
Completion of Hot Product Validations
at High Volumes                                   First Quarter 2001                   150,000
-------------------------------------------------------------------------------------------------

</TABLE>

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Appendix I: Detailed Breakdown of Cost

ADDITIONAL EQUIPMENT (US $ 255,000). These cost cover necessary additional
equipment. In detail:

<TABLE>
<CAPTION>

-------------------------------------------------------------------------------------------
<S>                                                                            <C>
         Box 0:  procedure and equipment for waste reduction, storage          US $  55,000
         and handling

         Box 3:  storage of foils (to be assembled within week)                US $  50,000

         Two additional assembly platforms: Leak-tight boxes, airlocks         US $  70,000
         with pneumatic gates, filters, gloves, maintenance covers with
         gloves (rear side, control for gates, improved feeding of
         capsulate, filters, particle monitoring)

         Additional personnel cost                                             US $  80,000
-------------------------------------------------------------------------------------------
                     Development Component Total                               US $ 255,000
-------------------------------------------------------------------------------------------
</TABLE>

DEVELOPMENT COMPONENT (US $ 191,000). These cost cover the change of capacity
from 40 to 200 activity carriers per week. In detail:

--------------------------------------------------------------------------------
         Box 0 Waste storage and handling

         Doubling the capacity of box 2

         Separate containment for acetone handling

         Setting up measurement equipment to measure the active foils

         Setting up measurement equipment to measure the geometric
         activity distribution and its homogeneity

         Introduction of a 4th assembly platform

--------------------------------------------------------------------------------
                     Development Component Total                    US $ 191,000
--------------------------------------------------------------------------------

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VALIDATION (US $ 240,000). These cost cover the validation of the chemical and
the manufacturing process as well as the validation/overhead costs. In detail:

--------------------------------------------------------------------------------
Validation of the chemical process

         Further optimization and reproducibility of high yield

         Waste reduction

         Stability of the labeling process

         Reproducibility of the homogenous dose distribution of the
         activity carrier
--------------------------------------------------------------------------------
                                                     Subtotal        US $ 90,000
--------------------------------------------------------------------------------

--------------------------------------------------------------------------------
Validation of the manufacturing process

         Manufacturing test catheters for validation

         Manufacturing under a higher degree of automation at the higher
         capacity of 200 catheters per week

         Clean room environment, bio-burden control, monitoring
--------------------------------------------------------------------------------
                                                     Subtotal        US $ 90,000
--------------------------------------------------------------------------------

--------------------------------------------------------------------------------
Validation/overhead costs

         Procurement of raw materials

         Procurement of packaging

         Sterilization

         Logistics for delivery of raw material to BEBIG and
         distribution of catheters to users

--------------------------------------------------------------------------------
                                                     Subtotal        US $ 60,000
--------------------------------------------------------------------------------
                                             Validation Total        US $240,000
--------------------------------------------------------------------------------EXHIBIT 4.1(bbbb)

                           AMENDMENT OF RIGHTS PLAN

      AMENDMENT (this "Amendment"), dated as of August 18, 2000, to the Rights
Agreement (the "Rights Agreement"), dated as of June 26, 1997 and amended as of
March 8, 1998 and further amended as of April 13, 1999, by and between
Pathogenesis Corporation, a Delaware corporation (the "Company"), and Harris
Trust and Savings Bank, an Illinois banking corporation, as Rights Agent (the
"Rights Agent"), at the direction of the company.

                                 R E C I T A L S
                                 - - - - - - - -

        A.      The Company has entered into an Agreement and Plan of Merger,
dated as of August 13, 2000 (as it may be amended or supplemented from time to
time, the "Merger Agreement") by and among the Company, Chiron Corporation, a
Delaware corporation ("Chiron"), and Picard Acquisition Corp., a wholly owned
subsidiary of Chiron ("Merger Sub"), with respect to a tender offer by Merger
Sub for shares of common stock, par value $0.001 per share, of the Company,
followed by the merger of Merger Sub with and into the Company (the "Merger").

        B.      Pursuant to Section 27 of the Rights Agreement, the Company may
from time to time supplement or amend the Rights Agreement in accordance with
the provisions of Section 27 thereof.

        C.      The Board of Directors has approved and declares advisable the
Offer (as defined in the Merger Agreement), the Merger (as defined in the Merger
Agreement) and the Merger Agreement and the transactions contemplated by the
Merger Agreement and has declared that it is in the best interests of the
Company's stockholders that the Company enter into the Merger Agreement and
consummate the Offer (as defined in the Merger Agreement) and the Merger (as
defined in the Merger Agreement) on the terms and subject to the conditions set
forth in the Merger Agreement.

        D.      The Board of Directors determined on August 13, 2000 that it is
in the best interests of the Company and its stockholders to amend the Rights
Agreement to exempt the Offer (as defined in the Merger Agreement), the Merger
(as defined in the Merger Agreement) and the Merger Agreement, and all of the
transactions contemplated by the Merger Agreement, from the application of the
Rights Agreement.

        E.      The Merger Agreement contemplates that the Rights Agreement
will be amended to exempt the Offer (as defined in the Merger Agreement), the
Merger (as defined in the Merger Agreement) and the Merger Agreement, and all
of the transactions contemplated by the Merger Agreement, from the application
of the Rights Agreement.

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                                A G R E E M E N T
                                - - - - - - - - -

      NOW, THEREFORE, in consideration of the foregoing and the covenants set
forth herein, the Company hereby directs, and the parties hereto agree that, the
Rights Agreement is amended as follows:

        1.      The definition of "Acquiring Person" in Section 1(a) of the
Rights Agreement is hereby amended by adding the sentence at the end thereof:

        "Notwithstanding anything to the contrary in this Agreement, none of
        Chiron Corporation, a Delaware corporation ("Chiron"), and its
        subsidiaries (including Picard Acquisition Corp., a Delaware
        corporation and wholly owned subsidiary of Chiron ("Merger Sub")),
        shall be deemed to be an Acquiring Person by reason of the execution,
        delivery or performance of the Agreement and Plan of Merger, dated as
        of August 13, 2000, by and among the Company, Chiron, and Merger Sub
        (as it may be amended from time to time, the "Merger Agreement"), or
        the consummation of the Offer (as defined in the Merger Agreement), the
        Merger (as defined in the Merger Agreement) or the other transactions
        contemplated by the Merger Agreement."

        2.      The definition of "Stock Acquisition Date" in Section 1(v) of
the Rights Agreement is hereby amended by adding the following to the end
thereof (immediately preceding the period):

        "; provided that a "Stock Acquisition Date" shall not occur solely by
        reason of the execution, delivery or performance of the Merger Agreement
        or the consummation of the Offer (as defined in the Merger Agreement),
        the Merger (as defined in the Merger Agreement) or the other
        transactions contemplated by the Merger Agreement."

        3.      Section 3(b) of the Rights Agreement is hereby amended by adding
the following sentence to the end thereof:

        "Notwithstanding anything to the contrary in this Agreement, a
        "Distribution Date" shall not occur solely by reason of the execution
        and delivery of the Merger Agreement or the consummation of the Offer
        (as defined in the Merger Agreement), the Merger (as defined in the
        Merger Agreement) or the other transactions contemplated by the Merger
        Agreement."

        4.      Section 7(a) of the Rights Agreement is hereby amended by
deleting the word "or" between clauses (ii) and (iii) of the second sentence of
Section 7(a)and adding the following to the end thereof (immediately preceding
the period):

        ", or (iv) the time  immediately  prior to the Acceptance Date (as
        defined in the Merger Agreement)."

        5.      Section 15 of the Rights Agreement is hereby amended by adding
the following sentence at the end thereof:

        "Notwithstanding the foregoing, nothing in this Agreement shall be
        construed to give any holder of Rights or any other Person any legal or
        equitable rights, rem-

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        edy or claim under this Agreement in connection with the Offer (as
        defined in the Merger Agreement), the Merger (as defined in the Merger
        Agreement) or any other transactions contemplated by the Merger
        Agreement."

        6.      This Amendment shall be deemed to be a contract made under the
laws of the State of Delaware and for all purposes shall be governed by and
construed in accordance with the laws of such State applicable to contracts to
be made and performed entirely within such State, without giving to its
principles of conflicts of laws.

        7.      This Amendment may be executed in any number of counterparts,
each of which shall be an original, but such counterparts shall together
constitute one and the same instrument.

        8.      Terms not defined herein shall, unless the context otherwise
requires, have the meanings assigned to such terms in the Rights Agreement.

        9.      In all respects not inconsistent with the terms and provisions
of this Amendment, the Rights Agreement is hereby ratified, adopted, approved
and confirmed. In executing and delivering this Amendment, the Rights Agent
shall be entitled to all the privileges and immunities afforded to the Rights
Agent under the terms and conditions of the Rights Agreement.

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             IN WITNESS WHEREOF, this Amendment has been duly executed by the
Company and the Rights Agent as of the day and year first written above.

Attest:                                      PATHOGENESIS CORPORATION
------

By: /s/ Marvin B. Tepper                  By: /s/ Wilbur H. Gantz
   --------------------------                --------------------------
   Name:  Marvin B. Tepper                   Name:  Wilbur H. Gantz
   Title: Secretary                          Title: Chairman and Chief
                                                    Executive Officer

Attest:                                      HARRIS TRUST AND SAVINGS BANK,
------                                              AS RIGHTS AGENT

By: /s/ Susan M. Shadel                   By: /s/ M. J. McHale
   --------------------------                --------------------------
   Name:  Susan M. Shadel                    Name:  M. J. McHale
   Title: Relationship Manager               Title: Vice President

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