<PAGE>
                                                                    EXHIBIT 4.12

(ASHURST MORRIS CRISP LOGO)

MANUFACTURING AGREEMENT

Protherics UK Limited

and

Chesapeake Biological Laboratories Inc.






























19 March 2003


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                                    CONTENTS

<TABLE>
<CAPTION>

CLAUSE                                                                                                      PAGE

<S>     <C>                                                                                                 <C>
1.       DEFINITIONS AND INTERPRETATION.......................................................................1
2.       PRODUCTION OF FINISHED PRODUCTS BY CHESAPEAKE........................................................5
3.       SUPPLY OF BULK PRODUCTS BY PROTHERICS................................................................9
4.       DELIVERY OF FINISHED PRODUCTS.......................................................................10
5.       PACKAGING OF FINISHED PRODUCTS......................................................................11
6.       VARIATIONS TO THE SPECIFICATION AND TECHNICAL AGREEMENT.............................................13
7.       INSPECTIONS AND RESPONSIBILITIES OF THE PARTIES.....................................................13
8.       YIELD...............................................................................................17
9.       PRICE AND PAYMENT...................................................................................19
10.      DEFECTS.............................................................................................21
11.      WARRANTIES..........................................................................................21
12.      LIMITATION OF LIABILITY.............................................................................23
13.      EXPERT DETERMINATION................................................................................24
14.      FORCE MAJEURE.......................................................................................25
15.      DURATION AND TERMINATION............................................................................25
16.      CONFIDENTIALITY.....................................................................................27
17.      INTELLECTUAL PROPERTY :.............................................................................28
18.      COSTS...............................................................................................29
19.      VARIATIONS..........................................................................................29
20.      WAIVER..............................................................................................29
21.      INVALIDITY..........................................................................................29
22.      NOTICES.............................................................................................29
23.      NO PARTNERSHIP......................................................................................30
24.      ASSIGNMENT AND SUB-CONTRACTING......................................................................31
25.      GOVERNING LAW AND JURISDICTION......................................................................31
26.      EXCLUSION OF THIRD PARTY RIGHTS.....................................................................32
27.      ENTIRE AGREEMENT....................................................................................32

SCHEDULE 1...................................................................................................33
Finished Products............................................................................................33
SCHEDULE 2...................................................................................................34
Specification................................................................................................34
SCHEDULE 3...................................................................................................41
Technical Agreement..........................................................................................41
SCHEDULE 4...................................................................................................42
Price........................................................................................................42
SCHEDULE 5...................................................................................................43
Quality Control Certificate of Release.......................................................................43
CERTIFICATE OF RELEASE.......................................................................................43
BULK PRODUCT.................................................................................................43
SCHEDULE 6...................................................................................................44
Postponement Fees............................................................................................44
SCHEDULE 7...................................................................................................45
Chargeable Regulatory Affairs Support Service................................................................45
SCHEDULE 8...................................................................................................46
Numbers of Vials, specified according to the Finished Product they contain, as are to be deducted in the
       calculation of the Target.............................................................................46
</TABLE>


<PAGE>



THIS AGREEMENT is made on 19 March 2003

BETWEEN:-

(1)      PROTHERICS UK LIMITED (No. 3464264) whose registered office is at
         Blaenwaun, Ffostrasol, Llandysul, Ceredigion SA44 5JT, UK
         ("PROTHERICS"); and

(2)      CHESAPEAKE BIOLOGICAL LABORATORIES INC. (No. D01116516) whose
         registered office is at Camden Industrial Park, 1111 S. Paca Street,
         Baltimore, M.D. 21230-2591, USA ("CHESAPEAKE").

RECITALS

(A)      Protherics carries on the business of selling Finished Products
         produced from Bulk Products, in each case as defined below.

(B)      Chesapeake carries on the business of freeze-drying and packaging
         pharmaceutical products such as Bulk Products.

(C)      Protherics wishes to engage Chesapeake to Manufacture (as defined
         below) Finished Products and Chesapeake is willing to undertake such
         work, on the terms and conditions set out in this agreement.

THE PARTIES AGREE AS FOLLOWS:-

1.       DEFINITIONS AND INTERPRETATION

1.1      In this agreement the following words and expressions shall have the
         following meanings, unless the context otherwise requires:-

         "AFFILIATE" means, in respect of each party, any company, partnership
         or other entity which directly or indirectly controls, is controlled by
         or is under the common control with such party;

         "BATCH" means a batch of Finished Products;

         "BATCH PRODUCTION AND CONTROL RECORD" means comprehensive histories,
         produced by Chesapeake, of the Manufacture of each Batch;

         "BUSINESS DAY" means any day (excluding Saturdays and Sundays) on which
         banks generally are open in the City of London for the transaction of
         normal banking business;

         "BUSINESS INFORMATION" means all business, commercial, economic,
         financial, operational, administrative, marketing, planning and staff
         information relating to a party or its interests;

         "BUFFER" means the solution supplied by Protherics to be used for
         wetting filters used in Manufacture;




                                      -1-
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"BULK PRODUCTS" means Protherics' bulk formulated proprietary antibody products
from which Finished Products are Manufactured, supplied by Protherics to
Chesapeake pursuant to this agreement;

"cGMP" means the Code of Federal Regulations, Part 21, Sections 210 and 211 and
such other Sections thereof as are designated by the title "Good Manufacturing
Practices" and promulgated under the United States Federal Food, Drug and
Cosmetic Act, as are in effect from time to time;

"CHANGE CONTROL" means Protherics' system of evaluating, notifying and
documenting planned changes from previously accepted practice and the impact
thereof on the quality, safety and efficacy of Finished Products as regards the
materials, components (including without limitation packaging, labeling and
Materials), products, processes, computer systems, utilities or testing
procedures, used or involved in or relating to the Manufacture, storage or
delivery of Finished Products, whenever, howsoever and wherever in the course
thereof they are relevant;

"CHANGE CONTROL COMMITTEE" means the committee established and appointed by
Protherics from time to time, which is responsible for operating Change Control;

"EFFECTIVE DATE" means the date of this agreement;

"EMEA" means the European Medicines Evaluation Agency;

"EXPERT" means a person to whom reference is made pursuant to clause 13.2 and
who is appointed as specified therein;

"EXPERT DETERMINATION" means the determination of a dispute or difference
between the parties by an Expert, in accordance with clause 13;

"FACILITY" means Chesapeake's facility for the sterile filtration, filling and
freeze-drying of pharmaceutical products at Camden Industrial Park, 1111 S. Paca
Street, Baltimore, M.D. 21230-2591, USA;

"FDA" means the United States Food and Drug Administration;

"FDA APPROVAL" means the receipt by Protherics of confirmation from the FDA that
the FDA approves Chesapeake to Manufacture Finished Products on the licence
concerning Finished Products granted to Protherics by the FDA;

"FINAL RELEASE" means final approval for sale of Finished Products given by the
relevant Regulatory Authority or Regulatory Authorities and/or by Protherics,
and in the event that such approval is given by Protherics and one or more
Regulatory Authorities, the last such approval so given;

"FINISHED PRODUCTS" means the products specified in schedule 1;

"INTELLECTUAL PROPERTY RIGHTS" means any and all trade marks, rights in designs,
get-up, business names, copyrights, future copyrights and patents (whether
registered or not and any





                                      -2-
<PAGE>

applications to register or rights to apply for registration of any of the
foregoing), rights in inventions, know-how, trade secrets and other confidential
information and all other intellectual property rights of a similar or
corresponding nature, which may now or in the future subsist in any part of the
world;

"MATERIALS" means all materials, components and reagents, other than Bulk
Products and Buffer, used by Chesapeake in the Manufacture of Finished Products;

"MANUFACTURE" means the manufacture of Finished Products from Bulk Products
through their sterile filtration, filling and freeze-drying and the testing,
packing and labelling thereof, and "MANUFACTURED" and "MANUFACTURING" shall be
construed accordingly;

"MCA" means the United Kingdom Medicines Control Agency;

"PACK OF FINISHED PRODUCTS" means a pack containing the number of Vials of
Finished Products set out in the Specification, which such Vials shall be packed
in accordance with the Technical Agreement;

"PRODUCT INFORMATION" means all technical information and data relating to the
Bulk Products, Finished Products and Specification, and the contents of the
Technical Agreement;

"QUALITY CONTROL CERTIFICATE OF RELEASE" means a certificate of release in the
form attached to this agreement as schedule 5;

"QUALIFIED PERSON" has the same meaning as in European Directive 75/319/EEC;

"REGULATORY AUTHORITY" means the FDA, the MCA and EMEA;

"REGULATORY INSPECTIONS" means an inspection by any Regulatory Authority of the
Facility or of Chesapeake's processes and/or equipment used in Manufacture or in
the storage of Finished Products, or any part or component thereof;

"REJECTS" means Vials rejected by Chesapeake or Protherics for containing
Finished Products not conforming to the Specification and/or not Manufactured,
stored, handled or transported in accordance with this agreement and the
Technical Agreement;

"RENEWAL DATE" means the second anniversary of the Effective Date;

"SPECIFICATION" means the specification for the Finished Products appended to
this agreement as schedule 2;

"TARGET" means, in respect of any Batch, the number of Vials comprising such
Batch as would be produced by utilising all Bulk Products supplied by Protherics
for use in the Manufacture of the Finished Products comprising such Batch and
were such quantity of such Bulk Products as Protherics specifies pursuant to
clause 3.3 to be included therein in the course of such Manufacture, less the
number of Vials within such Batch as are used by Chesapeake in conducting
sterility tests in accordance with the Technical Agreement, as specified in
schedule 8;



                                       -3-



<PAGE>
         "TECHNICAL AGREEMENT" means the agreed specification for Manufacture of
         the same date as the date hereof, a copy of which is appended to this
         agreement as schedule 3;

         "TECHNOLOGY TRANSFER PERIOD" means the period of six (6) months
         following the Effective Date;

         "VALUE ADDED TAX" means Value Added Tax or any other tax of a similar
         nature that may be substituted for or levied in addition to it, in each
         case at the rate current from time to time;

         "VIAL" means the type of vial to be used in packing Finished Products
         as part of Manufacture, as provided by the Technical Agreement,
         containing the appropriate quantity of the relevant Finished Product;

         "WATER FOR INJECTION" means water complying with the United States
         Environmental Protection Agency National Primary Drinking Water
         Regulations or comparable regulations of the European Union, purified
         by distillation and by reverse osmosis and containing no added
         substances; and

         "YIELD" means, in respect of any Batch, the number of Vials of Finished
         Products Manufactured in accordance with this agreement net of Rejects
         and which are potentially available for sale by Protherics in the
         course of its business.

1.2      In this agreement unless otherwise specified, reference to:-

         (a)      A "SUBSIDIARY" OR "HOLDING COMPANY" is to be construed in
                  accordance with section 736 of the Companies Act 1985;

         (b)      a party means a party to this agreement and includes its
                  permitted assignees and/or the respective successors in title
                  to substantially the whole of its undertaking;

         (c)      a person includes any person, individual, company, firm,
                  corporation, government, state or agency of a state or any
                  undertaking (whether or not having separate legal personality
                  and irrespective of the jurisdiction in or under the law of
                  which it was incorporated or exists);

         (d)      a statute or statutory instrument or any of their provisions
                  is to be construed as a reference to that statute or statutory
                  instrument or such provision as the same may have been or may
                  from time to time hereafter be amended or re-enacted;

         (e)      words denoting the singular shall include the plural and vice
                  versa and words denoting any gender shall include all genders;

         (f)      recitals, clauses or schedules are to recitals and clauses of
                  and schedules to this agreement. The schedules form part of
                  the operative provisions of this agreement and references to
                  this agreement shall, unless the context otherwise requires,
                  include references to the recitals and the schedules;







                                       -4-



<PAGE>

         (g)      "CONTROL" is to be construed in accordance with section 416 of
                  the Income and Corporation Taxes Act 1988 and "CONTROLLING"
                  and "CONTROLLED" shall be construed accordingly.

1.3      The index to and headings in this agreement are for information only
         and are to be ignored in construing the same.

2.       PRODUCTION OF FINISHED PRODUCTS BY CHESAPEAKE

2.1      Chesapeake shall Manufacture and store Finished Products at the
         Facility in accordance with the terms of this agreement, the Technical
         Agreement and cGMP, and shall ensure that such Finished Products comply
         with the Specification in all respects.

2.2      Protherics shall notify Chesapeake in writing of:

         (a)      its estimated forecast of the number of Vials of each of the
                  Finished Products which it will require to be Manufactured
                  each month during the subsequent twelve (12) months of the
                  term of this agreement, such forecasts to be given on a
                  rolling basis every month, the first to be given within ten
                  (10) Business Days following FDA Approval; and

         (b)      any revisions to the estimated forecast requirements that
                  Protherics has already given to Chesapeake pursuant to clause
                  2.2(a) above as soon as reasonably practicable after such
                  revisions are made.

2.3      (a)      Chesapeake shall notify Protherics of all proposed and
                  scheduled shutdowns or other suspensions of the operation of
                  the Facility or of any part or parts thereof or of any
                  machinery therein, the effect of which will or may be that for
                  the duration of the same Chesapeake will be unable to
                  Manufacture, at the relevant time, the Finished Products which
                  Protherics has notified Chesapeake in accordance with clause
                  2.2 above that Protherics estimates it will require to be
                  Manufactured in any particular month ("PROPOSED AND SCHEDULED
                  SHUTDOWNS").

          (b)     Chesapeake shall notify Protherics of all Proposed and
                  Scheduled Shutdowns (including of the dates thereof) as soon
                  as reasonably practicable after the same are first proposed or
                  scheduled to occur, as applicable, and shall in any event
                  confirm details thereof to Protherics in writing every six (6)
                  months of the term of this agreement, the first such
                  confirmation to be so given no later than ten (10) Business
                  Days after the Effective Date.

2.4      (a)      Protherics shall, on each occasion that it gives Chesapeake
                  notice of its estimated forecast requirements for Finished
                  Products pursuant to clause 2.2(a) above, give Chesapeake its
                  binding order in writing for the quantities of each of the
                  Finished Products which it will require Chesapeake to
                  Manufacture in a single month after that in which such binding
                  order is given.

         (b)      Each binding order given by Protherics pursuant to clause
                  2.4(a) above shall specify the week of the month to which such
                  binding order relates in which Protherics would like
                  Chesapeake to Manufacture the Finished Products ordered
                  thereby.



                                       -5-


<PAGE>

         (c)      Protherics shall ensure that it gives Chesapeake each binding
                  order pursuant to clause 2.4(a) above at least sixty five (65)
                  Business Days prior to the commencement of the month to which
                  such binding order relates.

         (d)      Protherics shall give no binding order pursuant to clause
                  2.4(a) above for Finished Products which it knows Chesapeake
                  will not be able to Manufacture when specified in such binding
                  order because of any Proposed and Scheduled Shutdowns of which
                  Protherics has been notified pursuant to clause 2.3.

2.5      (a)      As soon as reasonably practicable following receipt of any
                  binding order pursuant to clause 2.4(a) above, Chesapeake
                  shall determine when it will Manufacture the Finished Products
                  to which such binding order relates, which Manufacture shall,
                  subject to clause 2.5(b) below, take place during the week
                  specified by Protherics pursuant to clause 2.4(b) above (the
                  "ALLOCATED MANUFACTURING DATE").

         (b)      Notwithstanding clause 2.5(a) above, provided that Chesapeake
                  has Protherics' prior written consent so to do, Chesapeake may
                  schedule an Allocated Manufacturing Date other than in the
                  week specified by Protherics pursuant to clause 2.4(b) above
                  in the binding order for the Finished Products to be
                  Manufactured on such Allocated Manufacturing Date.

         (c)      Chesapeake shall notify Protherics in writing of each
                  Allocated Manufacturing Date no later than two (2) Business
                  Days after receipt of the binding order to which it relates or
                  the day forty (40) Business Days prior to such Allocated
                  Manufacturing Date, whichever is the later to occur.

2.6      Chesapeake shall use all reasonable endeavours to avoid scheduling any
         shutdowns or other suspensions of the operation of the Facility or of
         any part or parts thereof or of any machinery therein, the effect of
         which will or may be that Chesapeake will be unable to Manufacture any
         Finished Products on the relevant Allocated Manufacturing Date and
         supply the same to Protherics in accordance with this agreement in the
         month specified in the relevant binding order therefor given pursuant
         to clause 2.4(a) above, provided that this clause shall not prevent
         Chesapeake scheduling any such shutdowns which are necessary in the
         event of any emergency or other similar occurrence.

2.7      (a)      Subject to clause 2.7(b) below, Chesapeake shall Manufacture
                  and supply such quantities of Finished Products as Protherics
                  may order pursuant to clause 2.4(a) above in accordance with
                  the binding orders given pursuant to that clause, including
                  without limitation by:

                  (i)      Manufacturing the same on the relevant Allocated
                           Manufacturing Date therefor determined in accordance
                           with clause 2.5 above; and

                  (ii)     supplying such Finished Products to Protherics in
                           accordance with this agreement in the month specified
                           in the relevant binding order therefor;

                   provided that Protherics supplies Chesapeake with sufficient
                   quantities of Bulk Products and Buffer for Chesapeake so to
                   do.




                                      -6-
<PAGE>




         (b)      Notwithstanding the foregoing, Chesapeake may:

                  (i)      Manufacture Finished Products up to ten (10) Business
                           Days after the relevant Allocated Manufacturing Date
                           therefor; or

                  (ii)     with Protherics' prior written consent, Manufacture
                           Finished Products up to ten (10) Business Days before
                           the relevant Allocated Manufacturing Date therefor;

                  without breaching clause 2.7(a) above.

2.8      (a)      Protherics may request the postponement of the scheduled
                  Manufacture of any Finished Products which it has, in
                  accordance with this agreement, ordered to be Manufactured (a
                  "SCHEDULED FILL") to a date after the Allocated Manufacturing
                  Date therefor, by giving written notice to Chesapeake.

         (b)      If Protherics requests the postponement of any Scheduled Fill
                  by twenty (20) Business Days or less, Chesapeake shall use its
                  best endeavours to Manufacture the Finished Products relevant
                  thereto on the date to which Protherics requests such
                  Manufacture to be postponed, failing which, Chesapeake will
                  Manufacture such Finished Products as soon as it can
                  thereafter.

         (c)      If Protherics requests the postponement of any Scheduled Fill
                  by more than twenty (20) Business Days, including without
                  limitation pursuant to clause 2.11(a) below, Chesapeake shall
                  use all reasonable endeavours to Manufacture the Finished
                  Products relevant thereto on the date to which Protherics
                  requests such Manufacture to be postponed, failing which,
                  Chesapeake will Manufacture such Finished Products as soon as
                  reasonably practicable thereafter.

         (d)      In the event that Protherics requests the postponement of any
                  Scheduled Fill pursuant to clause 2.8(a) above, Protherics may
                  revoke the postponement thereof, in which event Chesapeake
                  shall use all reasonable endeavours to Manufacture the
                  Finished Products applicable thereto on the Allocated
                  Manufacturing Date for such Finished Products or as soon as
                  reasonably practicable thereafter.

         (e)      Without prejudice to clauses 2.8(d) above and 2.9(e) below, in
                  the event that Protherics requests the postponement of any
                  Scheduled Fill, Chesapeake shall use all reasonable endeavours
                  to arrange to manufacture alternative products for any of its
                  other clients on the Allocated Manufacturing Date therefor.

2.9      (a)      Subject to clauses 2.9(b), (c), (d) and (e) below, Protherics
                  shall be liable to pay Chesapeake a postponement fee in
                  respect of each Scheduled Fill which it requests pursuant to
                  clause 2.8(a) above be postponed by more than twenty (20)
                  Business Days, such fee to be as provided in schedule 6.

         (b)      In the event that Protherics requests the postponement of any
                  Scheduled Fill, and following the revocation of such
                  postponement pursuant to clause 2.8(d) above, the same takes
                  place on the Allocated Manufacturing Date therefor, Protherics
                  shall be




                                      -7-
<PAGE>


                  deemed not to have postponed such Scheduled Fill and shall not
                  be liable to pay any postponement fee pursuant to clause
                  2.9(a) in respect thereof.

         (c)      In the event that Protherics requests the postponement of any
                  Scheduled Fill and Chesapeake manufactures any product for any
                  other client of Chesapeake on any Allocated Manufacturing Date
                  for such Scheduled Fill, in accordance with clause 2.8(e)
                  above, Protherics shall not be liable to pay any postponement
                  fee pursuant to clause 2.9(a) above in respect thereof.

         (d)      In the event that Protherics requests the postponement of a
                  Scheduled Fill before having been notified pursuant to clause
                  2.5(c) above of the Allocated Manufacturing Date for the
                  Finished Products relevant thereto, Protherics shall not be
                  liable to pay Chesapeake a postponement fee pursuant to clause
                  2.9(a) above in respect of the same.

         (e)      In the event that Protherics requests the postponement of any
                  Scheduled Fill pursuant to clause 2.8(a) above, Protherics
                  may, at the time of so requesting the postponement of such
                  Scheduled Fill, notify Chesapeake that it would like
                  Chesapeake to Manufacture other Finished Products (whether or
                  not already ordered by Protherics to be Manufactured at some
                  future date) in place of those relevant to such Scheduled
                  Fill, in which event Chesapeake shall, notwithstanding that
                  the Manufacture of the same may not have been ordered in
                  accordance with clause 2.4(a) above, Manufacture such other
                  Finished Products in place of those relevant to such Scheduled
                  Fill on the Allocated Manufacturing Date for those relevant to
                  such Scheduled Fill (provided that Protherics supplies
                  sufficient quantities of Bulk Products and Buffer for
                  Chesapeake so to do), in which event Protherics shall not be
                  liable to pay any postponement fee pursuant to clause 2.9(a)
                  above in respect of the postponement of the Manufacture of the
                  same.

2.10     (a)      Notwithstanding the foregoing but subject to clause 2.10(b)
                  below, if Protherics postpones more than three (3) Scheduled
                  Fills in any twelve (12) months period, Protherics shall be
                  liable to pay Chesapeake a postponement fee in respect of each
                  Scheduled Fill which Protherics postpones thereafter, such fee
                  to be as provided in schedule 6, provided that Protherics
                  shall not be required to pay more than one (1) such
                  postponement fee in respect of any given postponement of any
                  Scheduled Fill.

         (b)      In the event that clause 2.10(a) above applies, the provisions
                  thereof shall remain in force until a period of twelve (12)
                  months has passed during which Protherics postpones no more
                  than three (3) Scheduled Fills.

         (c)      The provisions of clause 2.10(a) above may apply more than
                  once during the term of this agreement.

2.11     (a)      Subject to 2.11(b) below, in the event that Protherics
                  postpones more than three (3) Scheduled Fills in any twelve
                  (12) months period, Protherics shall give Chesapeake at least
                  forty (40) Business Days' notice of the date on which it would
                  like the Finished Products relevant to any further Scheduled
                  Fills which it postpones to be Manufactured.





                                       -8-


<PAGE>



         (b)      In the event that clause 2.11(a) above applies, the
                  provisions thereof shall remain in force until a period of
                  twelve (12) months has passed during which Protherics
                  postpones no more than three (3) Scheduled Fills.

         (c)      The provisions of clause 2.11(a) above may apply more than
                  once during the term of this agreement.

         (d)      In the event that clause 2.11(a) applies such that a
                  Scheduled Fill which Protherics had requested be postponed by
                  twenty (20) Business Days or less is postponed by more than
                  twenty (20) Business Days, such postponement shall be deemed
                  to be for less than twenty (20) Business Days for the purposes
                  of clauses 2.8(b) and (c) above.

2.12     Chesapeake shall invoice Protherics for any sums due pursuant to clause
         2.9(a) above no sooner than forty (40) Business Days following the same
         becoming due and all such invoices shall be payable in accordance with
         clause 9.4 below.

2.13     Chesapeake shall, as specified therein, report to Protherics the
         results of all tests which it conducts pursuant to the Technical
         Agreement.

2.14     Chesapeake shall obtain and maintain at its own expense and risk, all
         equipment, plant, apparatus and appliances necessary to enable it to
         store the Bulk Products, Buffer and all Materials and to Manufacture
         and store Finished Products in accordance with cGMP, the Technical
         Agreement and this agreement.

2.15     Chesapeake shall provide and maintain clean and safe storage for all
         Bulk Products, Buffer and Materials in accordance with cGMP and the
         Technical Agreement.

2.16     Chesapeake shall obtain all Materials and other components used in the
         Manufacture of Finished Products (except for Bulk Products and Buffer)
         and only from sources approved in advance by Protherics.

2.17     Within twenty five (25) Business Days of completing the Manufacture of
         each Batch, Chesapeake shall send Protherics a Batch Production and
         Control Record in respect thereof.

3.       SUPPLY OF BULK PRODUCTS BY PROTHERICS

3.1      Chesapeake shall accept such quantities of Bulk Products and Buffer as
         Protherics delivers to the Facility from time to time.

3.2      Chesapeake shall use all Bulk Products received from Protherics to
         Manufacture Finished Products in accordance with this agreement and
         shall be responsible for ensuring that it is able to do so, subject to
         Protherics providing Chesapeake with sufficient Buffer for that
         purpose.

3.3      Protherics shall ensure that each delivery of Bulk Products is
         accompanied by a Quality Control Certificate of Release, which shall
         specify the quantity of such Bulk Products as are to be incorporated
         within each Vial in the course of Manufacturing the Finished Products
         contained therein and as are Manufactured from such Bulk Products.


                                       -9-

<PAGE>



3.4      Chesapeake shall store all Bulk Products obtained from Protherics in
         accordance with clause 3 of the Technical Agreement and, upon receipt
         of each delivery thereof, shall conduct those inspections specified in
         clause 2.5 of the Technical Agreement and shall promptly inform
         Protherics of any non-conformance which it discovers thereby.

3.5      (a)      Title and risk in the Bulk Products shall remain with
                  Protherics at all times.

         (b)      Notwithstanding the above, but without prejudice to
                  Protherics' other rights and remedies hereunder, Chesapeake
                  shall reimburse Protherics for the cost of all Bulk Products
                  lost or destroyed while in Chesapeake's custody or under its
                  control, subject to a limit of [*] in respect of the
                  Manufacture of which the same were or would have been
                  utilised, and all payments due under this clause shall be made
                  by Chesapeake to Protherics by credit note, direct
                  reimbursement or at the reasonable discretion of Protherics.

3.6      Protherics shall provide Chesapeake with reasonable information
         concerning the Finished Products to assist Chesapeake in understanding
         and discharging its obligations under this agreement and with details
         of any relevant requirements of any Regulatory Authority.

4.       DELIVERY OF FINISHED PRODUCTS

4.1      (a)      Within ten (10) Business Days after freeze-drying each Batch
                  as part of the process of Manufacturing the same, Chesapeake
                  shall make available such number of properly filled, labelled
                  and packaged Vials as Protherics requests containing Finished
                  Products from such Batch and no other ("ADVANCED SAMPLES") for
                  Protherics' designated carrier to take delivery of the same at
                  the Facility.

         (b)      Chesapeake shall notify Protherics of the date on which such
                  Advanced Samples will be ready for Protherics' designated
                  carrier to take delivery of the same, such notice to be given
                  at least three (3) Business Days before the end of the ten
                  (10) Business Days period specified in clause 4.1(a) above.

         (c)      No less than one (1) Business Day prior to the day on which
                  Protherics' designated carrier will take delivery of such
                  Advanced Samples, Protherics shall inform Chesapeake of such
                  carrier's identity and of such carrier's estimated time of
                  arrival at the Facility, which shall be during Chesapeake's
                  normal business hours.

4.2      (a)      Without prejudice to clause 4.1 above, Chesapeake shall make
                  available the properly filled, labelled and packaged Finished
                  Products ordered by Protherics in accordance with clause 2,
                  less such as were comprised within already delivered Advanced
                  Samples, for Protherics' designated carrier to take delivery
                  of the same at the Facility.

         (b)      Protherics shall arrange for its designated carrier to take
                  delivery of such Finished Products within ten (10) Business
                  Days following Final Release thereof and shall notify
                  Chesapeake of the date on which such carrier will so take
                  delivery of the same, such notice to be given at least three
                  (3) Business Days before the end of such ten (10) Business
                  Days period.


* Material has been omitted pursuant to a request for confidential treatment
  and has been filed separately with the Commission.



                                      -10-


<PAGE>



         (c)      No less than one (1) Business Day prior to the day on which
                  Protherics' designated carrier will take delivery of such
                  Finished Products, Protherics shall inform Chesapeake of such
                  carrier's identity and of such carrier's estimated time of
                  arrival at the Facility, which shall be during Chesapeake's
                  normal business hours.

4.3      Chesapeake shall permit Protherics' designated carrier to take delivery
         of Finished Products pursuant to clauses 4.1 and 4.2 on the dates and
         times specified pursuant thereto or such other reasonable dates and
         times as such carrier may otherwise attend the Facility for such
         purpose within Chesapeake's normal business hours and shall give such
         carrier all reasonable assistance in so taking delivery of the same.

4.4      Subject to any contrary provisions herein, all deliveries of Finished
         Products pursuant to clauses 4.1 or 4.2 above shall be FCA (Incoterms
         2000) at the Facility, such that Chesapeake shall, without limitation,
         be responsible at its expense for loading the same at the Facility onto
         the relevant means of carriage therefor.

4.5      Title in the Finished Products shall vest in and remain at all times
         with Protherics whereas risk therein shall remain with Chesapeake until
         delivery, whereupon it shall pass to Protherics.

4.6      Protherics may appoint more than one carrier to take delivery of
         Finished Products in accordance with clauses 4.1 and 4.2, including of
         Finished Products within any given Batch, but shall in any event comply
         with the obligations in clauses 4.1(c) and 4.2(c) with respect to each
         such carrier.

4.7      Until such time as they are delivered to Protherics pursuant to clauses
         4.1 or 4.2 above, Chesapeake shall store all Finished Products and for
         the avoidance of doubt and in accordance with clause 2.1 above, shall
         ensure that such storage complies with the requirements of the
         Technical Agreement.

5.       PACKAGING OF FINISHED PRODUCTS

5.1      Protherics shall provide Chesapeake with details of Protherics' trade
         mark livery, together with any associated original artwork and relevant
         wording that Protherics requires be used on the packaging of and/or on
         the Finished Products or on the product-inserts to be packaged
         therewith, which livery, artwork and wording Chesapeake shall use on
         such packaging as directed by Protherics.

5.2      Subject to clause 5.3 below, Protherics shall give Chesapeake sixty
         five (65) Business Days' notice of any change in the trade mark livery,
         artwork or wording to be used on the packaging of and/or on the
         Finished Products or on the product-inserts to be packaged therewith,
         before Chesapeake shall be required to start using the same in
         accordance with clause 5.1 above.

5.3      If any Regulatory Authority requires a change to the packaging and/or
         labelling used on Finished Products, Protherics shall inform Chesapeake
         in writing within two (2) Business Days of being notified of such
         requirement and shall provide Chesapeake with full details of the
         changes to be made, in which event Chesapeake shall make such changes
         to the packaging of and/or labelling used on the Finished Products or
         on the product-inserts to be packaged therewith according to the time
         schedule dictated by such Regulatory Authority.



                                      -11-

<PAGE>



5.4       Protherics hereby grants Chesapeake a non-exclusive licence of those
          trade marks, details of which it provides Chesapeake pursuant to
          clauses 5.1 or 5.2 above, and its associated get-up, for the term of
          this agreement, only for the purpose of using the same on the
          packaging of and/or on the Finished Products, in accordance with
          Protherics' instructions, such licence neither to be assigned nor
          sub-licensed other than with Chesapeake's obligations pursuant to this
          agreement as provided for herein.

5.5       All use of Protherics' trade marks by Chesapeake shall at all times be
          for the benefit of Protherics and any goodwill accrued to Chesapeake
          by its use of such trade marks shall accrue to and be held in trust by
          Chesapeake for Protherics, which goodwill Chesapeake agrees to assign
          to Protherics at its request at any time, whether during or after the
          subsistence of this agreement, and this clause 5.5 shall survive the
          termination of this Agreement for whatever reason.

5.6       Notwithstanding the other provisions of this clause 5, Chesapeake
          shall provide Protherics with proofs of all packaging, labels and all
          product-inserts to be used on or for or to be packaged with the
          Finished Products, and shall use none of these without Protherics'
          prior approval. In the event that Protherics requests any changes to
          be made to such packaging or product-inserts, Chesapeake shall
          promptly effect such changes and re-submit the same to Protherics for
          approval.

5.7       (a)      Protherics shall provide Chesapeake with details of the
                   validated packaging plan for all Finished Products within ten
                   (10) Business Days following FDA Approval and, subject to
                   clause 5.7(b) below, Chesapeake shall ensure that all
                   Finished Products delivered pursuant to this agreement shall
                   be packaged for delivery as specified therein.

          (b)      Protherics may provide Chesapeake with amendments to the
                   validated packaging plan provided pursuant to clause 5.7(a)
                   above, including without limitation amendments thereto which
                   are specific to any particular Finished Product or in respect
                   of Finished Products to be transported to any particular
                   destination or destinations, in which event Chesapeake shall
                   ensure that all Finished Products delivered pursuant to this
                   agreement shall be packaged for delivery as specified in such
                   amended packaging plans.

          (c)      For the avoidance of doubt, Protherics may provide Chesapeake
                   with amendments to the validated packaging plans provided
                   pursuant to clause 5.7(a) above as and when Protherics
                   determines and on any number of occasions.

 6.       VARIATIONS TO THE SPECIFICATION AND TECHNICAL AGREEMENT

 6.1      (a)      Protherics may at any time propose a variation to the
                   Specification or to the Technical Agreement by written notice
                   to Chesapeake and Chesapeake's agreement to any such
                   variation shall not be unreasonably withheld or delayed,
                   provided that Protherics shall not propose a variation to the
                   Specification or to the Technical Agreement during the
                   Technology Transfer Period.

          (b)      If Chesapeake does not consent within twenty (20) Business
                   Days to a variation to the Specification or Technical
                   Agreement proposed by Protherics, Protherics shall be
                   entitled to give written notice to terminate this agreement
                   forthwith and without further


                                      -12-


<PAGE>



                  liability, unless Chesapeake acted reasonably in not giving
                  such consent within such time period.

         (c)      For the avoidance of doubt, Chesapeake shall not be considered
                  to have unreasonably withheld its consent to a variation to
                  the Specification or Technical Agreement proposed by
                  Protherics if such consent was withheld because implementing
                  the proposed variation would have caused Chesapeake to incur
                  expense which it would not otherwise have incurred, which
                  expense Protherics was not willing to bear.

         (d)      Chesapeake shall implement all agreed variations to the
                  Specification or Technical Agreement proposed by Protherics as
                  quickly as reasonably practicable following Chesapeake
                  consenting to the same in accordance herewith.

6.2      (a)      Chesapeake may, at any time, in order to comply with
                  applicable law, propose a variation to the Specification or
                  the Technical Agreement, in which event the parties shall
                  negotiate in good faith to agree the proposed variation and
                  the time scale in which to implement it in order to comply
                  with such law.

         (b)      Notwithstanding clause 6.2(a) above, all amendments to the
                  Technical Agreement or the Specification proposed by
                  Chesapeake must be presented by Chesapeake to Protherics in
                  such a manner and format as to enable the Change Control
                  Committee properly and fully to implement Change Control or in
                  any other appropriate way to assess the impact, if any, of
                  each such proposal on the quality, safety, efficacy and
                  composition of the Finished Products, and no such proposed
                  amendment shall be implemented until the Change Control
                  Committee has, acting reasonably, so properly and fully
                  implemented Change Control or otherwise assessed the impact of
                  such proposed amendment, as is appropriate in Protherics'
                  opinion.

7.       INSPECTIONS AND RESPONSIBILITIES OF THE PARTIES

7.1      (a)      If asked by any Regulatory Authority to provide it with any
                  information relating to the Finished Products, the Manufacture
                  or the work performed for Protherics by Chesapeake, Chesapeake
                  shall notify Protherics as soon as practicable of such request
                  and shall provide the information so requested in the time
                  scale stated by such Regulatory Authority, provided that
                  Protherics has first reviewed and has approved the same.

         (b)      If asked by Protherics to provide it with any documents,
                  information or other data relating to the Finished Products,
                  the Manufacture or the work performed for it by Chesapeake,
                  Chesapeake shall provide Protherics with the same without
                  delay.

7.2      Subject to clause 7.5 below, Chesapeake shall, on reasonable notice,
         permit Protherics' authorised representatives from time to time during
         normal working hours to enter and inspect the Facility and any other
         premises where Bulk Products, Finished Products, Materials or Buffer
         are processed in the course of or in relation to the Manufacture and/or
         where the same are stored (together and individually, the "PREMISES"),
         in order to:

         (a)      inspect the Premises and all equipment therein used in or in
                  connection with the Manufacture;


                                      -13-


<PAGE>



         (b)      inspect and take away samples of Finished Products, Bulk
                  Products, Buffer and Materials;

         (c)      observe and inspect operations, methods and records relating
                  to the Manufacture and Chesapeake's storage or handling of
                  Finished Products, Bulk Products, Materials and Buffer,
                  including without limitation manufacturing and quality control
                  records;

         (d)      audit the Manufacture for compliance with Regulatory Authority
                  requirements;

         (e)      review Chesapeake's facility master file, any correspondence,
                  reports or other documents from Chesapeake to any Regulatory
                  Authority or from any Regulatory Authority to Chesapeake,
                  relating to the Finished Products, Materials or the
                  Manufacture or, in so far as the same relate to the Finished
                  Products or the Manufacture, to the Premises; and

         (f)      approve any variances which occur during the Manufacture or
                  the storage or handling of Finished Products, Bulk Products,
                  Materials and Buffer, including without limitation approval of
                  the text of labels or other packaging used or to be used
                  therewith;

         and Chesapeake shall provide Protherics with reasonable assistance in
         so doing.

7.3      (a)      Should Protherics reasonably believe that Chesapeake is
                  failing or is at material risk of failing to Manufacture or
                  store Finished Products as required by this agreement,
                  Protherics will report such concerns to Chesapeake, in which
                  event, Protherics shall, in addition to its rights under
                  clause 7.2 above but subject to clauses 7.3(c) and 7.5 below,
                  be entitled to send a representative to attend the Premises to
                  monitor and report back to Protherics on Chesapeake's
                  Manufacturing and storage of Finished Products and its storage
                  and handling of Bulk Products, Buffer and Materials, and to
                  assist Chesapeake therewith.

         (b)      Chesapeake shall provide all reasonable assistance to any
                  representative of Protherics attending the Premises pursuant
                  to this clause 7.3, who shall be entitled to return to and to
                  remain there until Protherics is reasonably satisfied that
                  Chesapeake's Manufacturing and its storage of Finished
                  Products and its storage and handling of Bulk Products, Buffer
                  and Materials, complies with the requirements of this
                  agreement.

         (c)      No representative of Protherics attending the Premises
                  pursuant to this clause 7.3 may instruct Chesapeake to take
                  any steps or otherwise interfere with Chesapeake's performance
                  of its obligations under this agreement.

         (d)      No representative of Protherics attending the Premises
                  pursuant to this clause 7.3 shall be entitled to any permanent
                  office facilities or secretarial support from Chesapeake by
                  virtue hereof, but Chesapeake shall provide him with a
                  reasonable location within the Premises at which he will be
                  reasonably able to undertake such of his work as is of an
                  office-like nature, including by allowing him access to a
                  mains electricity power point



                                      -14-


<PAGE>


                  from which he shall be entitled to draw electricity for the
                  purposes of his work and by giving him reasonable access to
                  telephones.

         (e)      Notwithstanding the other provisions of this clause 7.3, no
                  representative of Protherics attending the Premises pursuant
                  hereto shall be entitled to enter such parts of the Premises
                  as are designated areas of restricted access within the same,
                  including without limitation clean rooms, but shall be
                  entitled to observe the interiors of such areas of restricted
                  access from outside thereof, including by closed circuit
                  television, where in operation.

7.4      (a)      Chesapeake shall permit any Regulatory Authority wishing to
                  conduct a Regulatory Inspection to do so whenever it chooses
                  or otherwise agrees with Chesapeake.

         (b)      Chesapeake shall notify Protherics of any pending Regulatory
                  Inspection at the earliest opportunity and, subject to clause
                  7.5 below, Protherics shall be entitled to send a
                  representative to be present at such Regulatory Inspection and
                  shall receive copies of all reports produced therefrom.

         (c)      Chesapeake shall provide all reasonable assistance to further
                  the objectives of any Regulatory Inspections, including
                  without limitation by answering all enquiries made in the
                  course thereof and providing the relevant Regulatory Authority
                  with access to all relevant records.

7.5       Protherics shall ensure that any representative which it sends to
          and/or who otherwise attends the Premises pursuant to this clause 7
          shall at all times comply with Chesapeake's regulations and
          instructions relating to the safety and conduct of persons thereat and
          such representative shall be so sent to and/or otherwise attend the
          Premises at Protherics' cost.

7.6      (a)      Insofar as is necessary for it to undertake the Manufacture
                  and to perform its obligations hereunder, in particular with
                  regard to the intention to use the Finished Products in human
                  clinical therapy, Chesapeake shall maintain its Annual
                  Registration of Drug Establishment (form FDA 2656e) and its
                  Annual Registration of Device Establishment (form FDA 289la)
                  granted by the FDA in good order and up to date and shall
                  promptly provide copies of the same and of all related
                  documents to Protherics upon request.

         (b)      Chesapeake shall file and maintain a facility master file as
                  required by the FDA and shall maintain Finished Products
                  complaint files pursuant to applicable United States Federal
                  regulations, in each case as provided by Chesapeake's then
                  current written standard operating procedures.

         (c)      Chesapeake shall maintain one or more facility master files at
                  the FDA and shall provide Protherics with any requisite
                  letters authorising the FDA to access the same in connection
                  with any Regulatory Inspection.

7.7       Chesapeake shall promptly notify Protherics of all communications
          which it receives from any Regulatory Authority, which relate to or
          may impact upon or affect the Manufacture or the Finished Products,
          and shall provide Protherics with copies of the same. In particular,
          Chesapeake shall promptly notify Protherics of any correspondence
          which it receives from any


                                      -15-


<PAGE>



         Regulatory Authority in respect of any audit of the Manufacture or of
         its procedures, methods or facilities, or which may in any way affect
         its ability to Manufacture Finished Products in accordance with this
         agreement, including without limitation any warnings received from any
         Regulatory Authority concerning any of the foregoing, and shall provide
         Protherics with details of the same and shall co-operate with
         Protherics in all reasonable respects as regards its response thereto
         and its handling of any issues raised thereby.

7.8      (a)      Protherics shall have sole responsibility at its own cost

                  (i)      for obtaining such approvals or permits as may be
                           applicable in respect of the distribution, export and
                           sale of the Finished Products to customers and for
                           complying with such other regulatory requirements as
                           are applicable in respect of the same and of the
                           Manufacture, other than those expressly stated
                           hereunder to be the responsibility of Chesapeake;

                  (ii)     for submitting claim files and applicable reports to
                           any applicable Regulatory Authority; and

                  (iii)    for obtaining such approvals or permits as may be
                           applicable to import Bulk Products into the United
                           States, including without limitation such as are
                           necessary from the United States Department of
                           Agriculture and, if requested, shall make copies of
                           such licences and consents available to Chesapeake.

         (b)      Chesapeake will provide Protherics with copies of all
                  documents required by Protherics to support Protherics'
                  applications for regulatory approvals or permits and with such
                  other reasonable assistance as is required by Protherics to
                  comply with other requirements referred to in clause 7.8(a).

         (c)      In the event that in complying with its obligations pursuant
                  to clause 7.8(b) above, Chesapeake undertakes work of any of
                  the types specified in schedule 7, Chesapeake may charge
                  Protherics for undertaking such work, at the rates specified
                  in schedule 7, provided that:

                  (i)      Chesapeake shall use all reasonable endeavours to
                           minimise such number of hours;

                  (ii)     before any such work is undertaken, Chesapeake shall
                           issue Protherics with a quote for the cost to
                           Protherics pursuant to this clause therefor and shall
                           not commence any such work until Protherics both
                           approves such quote and authorises such work in
                           writing; and

                  (iii)    notwithstanding the foregoing, without Protherics'
                           prior approval, Chesapeake shall not charge
                           Protherics any more for such work than it has quoted
                           pursuant to clause 7.8(c)(ii) above.

         (d)      Chesapeake shall invoice Protherics for sums due pursuant to
                  clause 7.8(c) following the completion of the work to which
                  such sums relate and such invoices shall be payable in
                  accordance with clause 9.4.



                                      - 16-



<PAGE>



7.9      Protherics shall without undue delay following a request for the same
         from Chesapeake, provide Chesapeake with such documents, information or
         data as Chesapeake may reasonably require to fulfil its obligations
         hereunder or as Protherics is expressly required by this agreement to
         provide to Chesapeake.

7.10     Protherics will notify Chesapeake without undue delay of any consumer
         or other complaints concerning the Finished Products which it receives
         and which might reasonably be attributed to any default on the part of
         Chesapeake.

8.       YIELD

8.1      Chesapeake shall use all reasonable endeavours to minimise waste of
         Bulk Products in Manufacture and shall, in any event, ensure that the
         Yield of each Batch is limited to between 92 per cent. and 100 per
         cent. of the Target.

8.2      (a)      Should the Yield of any Batch be less than the lower limit or
                  greater than the upper limit specified in clause 8.1 above (a
                  "NON-CONFORMING YIELD"), Chesapeake shall promptly notify as
                  much to Protherics and, should Protherics elect in its
                  discretion to reject the same pursuant to clause 10.1 below,
                  Chesapeake shall promptly reimburse Protherics in accordance
                  with clause 10.3 below.

         (b)      Should any Batch have a Non-Conforming Yield such that its
                  Yield is less than the lower limit specified in clause 8.1
                  above, and should Protherics elect in its discretion not to
                  reject the same pursuant to clause 10.1 below, Chesapeake
                  shall, without prejudice to Protherics' other rights and
                  remedies hereunder, reimburse Protherics for the difference
                  between the cost of the Bulk Products used in the Manufacture
                  of such Batch and the cost of the theoretical quantity of Bulk
                  Products which would have been used in the Manufacture of the
                  number of Vials within such Batch had the Finished Products
                  within such Vials have been Manufactured from such theoretical
                  quantity of Bulk Products and should the Yield thereof have
                  been 100% of the Target, subject to a limit of [*] in respect
                  of each such Batch.

         (c)      Payments due under this clause shall be made by Chesapeake to
                  Protherics by credit note, direct reimbursement or at the
                  reasonable discretion of Protherics.

 8.3     (a)      In the event that a Batch has a Non-Conforming Yield,
                  Chesapeake shall promptly upon becoming aware of as much
                  conduct an investigation to determine the cause thereof, with
                  which investigation Protherics shall co-operate in all
                  reasonable respects and in which it shall be entitled to
                  participate and to which it shall be entitled to have full
                  access, and Chesapeake shall, within five (5) Business Days
                  following the production of the relevant Batch, notify
                  Protherics of the occurrence of the same and of the Yield of
                  such Batch.

         (b)      Chesapeake shall submit to Protherics a written report of the
                  findings of the investigations conducted pursuant to clause
                  8.3(a) above within twenty (20) Business Days following the
                  date of Manufacture of the Batch to which they relate.

8.4      If Chesapeake experiences two (2) Non-Conforming Yields in any rolling
         twelve (12) month period, Protherics shall, in addition to its rights
         set out above, have the right to terminate this


* Material has been omitted pursuant to a request for confidential treatment
  and has been filed separately with the Commission.



                                      -17-


<PAGE>



         agreement without further liability by providing sixty (60) Business
         Days' written notice to Chesapeake.

8.5      (a)      Notwithstanding the above, but subject to clause 8.5(b) below,
                  the provisions of clauses 8.1, 8.2 and 8.4 above shall not
                  take effect until the date one (1) year after the Effective
                  Date, although Chesapeake shall use all reasonable endeavours
                  to minimise any waste of Bulk Products in the Manufacture of
                  the Finished Products Manufactured prior thereto.

         (b)      The application of clause 8.3 above shall not be affected by
                  clause 8.5(a), and clauses 8.1 and 8.2(a) above shall apply to
                  this agreement from and including the Effective Date solely in
                  so far as is necessary to give effect to the said clause 8.3.

         (c)      For the avoidance of doubt, clause 8.5(a) above shall not
                  effect Protherics' rights pursuant to clause 10.1 below.

8.6      In the event that the average Yield of the Batches Manufactured by
         Chesapeake in the year following the Effective Date, irrespective of
         which Finished Products comprise the same, is less than the lower limit
         or greater than the upper limit specified in clause 8.1 above,
         Chesapeake may request that the parties meet to discuss revising such
         limits, in which event the parties shall so meet as soon as reasonably
         practicable, provided that:

         (a)      Chesapeake can demonstrate that such average Yield was less
                  than such lower limit or greater than such upper limit, as
                  applicable, as a consequence of:

                  (i)      an inherent property of the Finished Products; or

                  (ii)     an incompatibility of the Finished Products or the
                           Manufacture with Chesapeake's Manufacturing process
                           or the machinery or other equipment used by
                           Chesapeake in Manufacture; and

                  was not due to the fault of Chesapeake; and

         (b)      Chesapeake makes such request between the first anniversary of
                  the Effective Date and the date falling thirty (30) Business
                  Days thereafter.

8.7      In the event that the parties meet pursuant to clause 8.6 above to
         discuss revising the permissible upper or lower limits of the Yield
         specified in clause 8.1 above and do not reach agreement on whether to
         revise the same or what such revised limits should be within thirty
         (30) Business Days (or such other time period as the parties agree) of
         first so meeting, either party may terminate this agreement forthwith
         by notice to the other, provided that such notice is given within five
         (5) Business Days of the end of such thirty (30) Business Days period
         (or such other time period as the parties may have agreed in accordance
         herewith).

8.8      In the event that, pursuant to clause 8.6 above, the parties discuss
         revising the upper or lower limits of the Yield specified in clause 8.1
         above, the provisions of clause 8.5 above shall additionally apply
         until the end of the thirty (30) Business Days period referred to in
         clause 8.7 above, provided that:



                                      -18-

<PAGE>



         (a)      Chesapeake has requested that the parties enter into such
                  discussions after the first anniversary of the Effective Date
                  but no later than thirty (30) Business Days after such
                  anniversary; and

         (b)      such discussions do not end prior to the end of the thirty
                  (30) Business Days period referred to in clause 8.7 above.

9.       PRICE AND PAYMENT

9.1      Chesapeake shall invoice Protherics in United States dollars in respect
         of its Manufacture and storage of Finished Products pursuant to this
         agreement, each such invoice to be issued upon and relate to:

         (a)      a delivery to Protherics of Finished Products comprised within
                  an Advanced Sample; or

         (b)      a delivery of Finished Products not comprised within an
                  Advanced Sample.

9.2      The sums for which Chesapeake may invoice Protherics pursuant to clause
         9.1 above shall be as set out in schedule 4, the figures therein to
         remain fixed unless varied in accordance with clauses 9.5 or 9.6.

9.3      The sums for which Chesapeake may invoice Protherics pursuant to clause
         9.1 above shall include all costs of insurance and all applicable
         taxes, excluding any United Kingdom Value Added Tax which may be
         payable in respect of the importation of Finished Products into the
         United Kingdom, which shall, if payable, be borne by Protherics.

9.4      Protherics shall pay Chesapeake the amount stated on each invoice
         issued to it pursuant hereto at the end of the calendar month following
         the date of such invoice and payment shall be made into a bank account
         designated by Chesapeake, details of which have been notified to
         Protherics from time to time.

9.5      (a)      The parties shall commence discussions:


                  (i)      one hundred (100) Business Days prior to the Renewal
                           Date; and

                  (ii)     one hundred (100) Business Days prior to every third
                           anniversary of the Renewal Date thereafter;

                   concerning whether to increase or decrease the figures
                   specified in schedule 4 and by how much, which discussions
                   the parties shall conduct in good faith, provided that
                   neither party shall be required by this clause to continue
                   such discussions as begin before the Renewal Date beyond the
                   Renewal Date, or such discussions as begin before any
                   anniversary of the Renewal Date beyond such anniversary.

         (c)      In the event that the parties agree any increase or decrease
                  in such figures, such increase or decrease shall take effect
                  from the Renewal Date or the relevant anniversary thereof, as
                  applicable.





                                      -19-


<PAGE>



         (d)      In the event that during any such discussions, the parties
                  fail to agree whether, and by how much, to increase or
                  decrease such figures, either party may terminate this
                  agreement upon not less than one (1) year's notice to the
                  other, provided that such notice is given within thirty (30)
                  Business Days following the end of the relevant discussions
                  further to which the parties so failed to reach agreement.

         (e)      In the event that either party gives notice pursuant to clause
                  9.5(d) above to terminate this agreement, the figures
                  specified in schedule 4 shall be increased by the lesser of:

                  (i)      such amount as Chesapeake may have requested by which
                           they be increased in the course of the discussions
                           pursuant to clause 9.5(a) above next preceding such
                           notice; and

                  (ii)     five (5%) percent;

                  and such figures, as increased in accordance with this clause
                  9.5(e), shall apply for the remainder of the term of this
                  agreement.

9.6       If at any time during the term of this agreement the parties agree
          pursuant to clause 6 to make changes to the Technical Agreement and/or
          the Specification and accordingly to alter the amount payable by
          Protherics for Finished Products, such alterations to such amounts
          payable shall take effect when the parties agree.

10.       DEFECTS

10.1      Protherics shall be entitled to reject any Finished Products which it
          determines do not conform with the Specification and to return them to
          Chesapeake or otherwise dispose of them as Chesapeake may direct, in
          either case, at Chesapeake's expense. Protherics shall act reasonably
          in determining whether any Finished Products are defective, which
          determination shall be conclusive.

10.2      Protherics shall upon becoming aware of the same notify Chesapeake of
          any defect in any Finished Products which occurs during transit to the
          designated recipient and by reason of which Protherics alleges that
          they do not conform with the Specification and because of which it has
          rejected the same.

10.3      In the event that Protherics rejects any Finished Products, Chesapeake
          shall, without prejudice to Protherics' other rights and remedies
          hereunder, reimburse Protherics for the cost of the Bulk Products used
          in the Manufacture of such rejected Finished Products, subject to a
          limit of [*] in respect of the Manufacture of which the same were
          utilised. Payments due under this clause shall be made by Chesapeake
          to Protherics by credit note, direct reimbursement or at the
          reasonable discretion of Protherics.

10.4      If any Finished Products are rejected by Protherics, Protherics shall
          not be required to pay any amount otherwise payable to Chesapeake in
          respect thereof.

11.       WARRANTIES

11.1      Chesapeake warrants that:


* Material has been omitted pursuant to a request for confidential treatment
  and has been filed separately with the Commission.



                                      -20-
<PAGE>

         (a)      it shall Manufacture, store and deliver Finished Products with
                  skill, competence, care and attention and in accordance with
                  the terms of this agreement, the Technical Agreement and all
                  appropriate legislation, and the rules and other requirements
                  of any appropriate Regulatory Authority which apply from time
                  to time, including without limitation cGMP.

         (b)      it shall at all times maintain in a clean, safe and hygienic
                  condition and in accordance with all appropriate statutes and
                  regulations:-

                  (i)      the Premises;

                  (ii)     the plant and machinery located in the Premises which
                           are used in connection with the Manufacture and
                           storage of Finished Products; and

                  (iii)    all packaging used or to be used for Finished
                           Products.

         (c)      the labels used by Chesapeake on the Finished Products will
                  conform with Protherics' requirements or those of any
                  applicable Regulatory Authority notified to Chesapeake
                  pursuant to clause 5 above and that the same shall not be used
                  without Protherics' prior approval;

         (d)      all Finished Products shall be of satisfactory quality and
                  shall, at the time of delivery to the designated recipient,
                  conform with the Specification.

         (e)      all Finished Products will, during their normal shelf life,
                  continue to conform to the warranties in this clause 11.1
                  provided always that they are correctly transported, stored
                  and handled;

         (f)      no Finished Products shall be misbranded or adulterated;

         (g)      all Bulk Products, Buffer and Materials shall be stored in
                  accordance with the requirements for storage specified in the
                  Technical Agreement.

11.2     Protherics warrants that:

         (a)      it is authorised to provide all instructions, specifications
                  and other information which it may give to Chesapeake in
                  connection with the Manufacture of Finished Products and that
                  in complying therewith, Chesapeake shall not infringe the
                  rights of any third party.

         (b)      subject to any default on the part of Chesapeake, if
                  Manufactured in accordance with the Specification, the
                  Technical Agreement and Protherics' other instructions, if
                  any, the Manufacture by Chesapeake of Finished Products will
                  not infringe any patent or other similar Intellectual Property
                  Right anywhere in the world belonging to any third party.

11.3     Chesapeake shall indemnify and hold harmless Protherics from and
         against:-





                                      -21-

<PAGE>



         (a)      all actions, demands, losses, costs (including reasonable
                  legal fees), claims, damage or liability, which Protherics may
                  suffer or incur from any third party claims that arise from
                  (i) a breach of any of Chesapeake's agreements or warranties
                  contained herein, (ii) Chesapeake's negligence or other
                  wrongful conduct or (iii) the Finished Products, their
                  Manufacture, storage, distribution, sale or use being in
                  violation of any third party Intellectual Property Right
                  (other than a claim covered under clause 11.4 below); and

         (b)      all actions, demands, losses, costs (including reasonable
                  legal fees), claims, damage or liability (excluding
                  consequential loss) which Protherics may suffer or incur
                  arising out of the Finished Products not complying with the
                  Specification (other than as a result of any defect in the
                  Bulk Products or any information supplied by or on behalf of
                  Protherics).

         It is a condition of the foregoing indemnity that Protherics shall
         forward to Chesapeake a copy of any claims, actions and demands, as
         soon as reasonably practicable and shall not admit any liability nor
         make any payment, settlement or compromise in respect thereof without
         the written consent of Chesapeake and that Chesapeake shall, if it so
         chooses and by prior written notice to Protherics, in the name of
         Protherics, control the conduct of the defence, settlement, compromise,
         counterclaim and all third party action in respect of such claims,
         actions and demands, provided that Chesapeake shall keep Protherics
         regularly informed as to the conduct thereof.

11.4     Protherics hereby undertakes to indemnify and hold harmless Chesapeake:

         (a)      from and against:-

                  (i)      all actions, demands, losses, costs (including
                           reasonable legal fees), claims, damage and liability
                           which Chesapeake may suffer or incur from any third
                           party claim arising from Protherics' breach of any of
                           its agreements or warranties contained herein or from
                           Protherics' negligence or other wrongful conduct; or

                  (ii)     as a result of a defect or error contained in any
                           incorrect or defective information or instructions
                           provided in writing by Protherics.

         It is a condition of the foregoing indemnity that Chesapeake shall
         forward to Protherics a copy of all such claims, actions and demands as
         soon as reasonably practicable and shall not admit any liability nor
         make any payment, settlement or compromise in respect thereof without
         the written consent of Protherics and that Protherics shall, if it so
         chooses and by prior written notice to Chesapeake, in the name of
         Chesapeake, control the conduct of the defence, settlement, compromise,
         counterclaim and all third party action in respect of such claims,
         actions and demands, provided that Protherics shall keep Chesapeake
         regularly informed as to the conduct thereof.

12.      LIMITATION OF LIABILITY

12.1     Nothing in this agreement shall limit Chesapeake's liability in respect
         of any claim:



                                      -22-


<PAGE>



         (a)      for death or personal injury caused by its negligence;

         (b)      under Part 1 of the Consumer Protection Act 1987;

         (c)      in respect of any liability which arises under any safety
                  regulation made under Section 10 of the Consumer Protection
                  Act 1987 and which such regulation does not allow to be
                  excluded; or

         (d)      any other liability which may not be limited or excluded at
                  law.

12.2     Neither party shall be liable to the other for any indirect or
         consequential loss or for any loss of profits or loss of goodwill which
         it may suffer even if such loss is reasonably foreseeable or if it had
         been advised of the possibility of incurring the same.

12.3     In the event that Chesapeake reimburses Protherics any sum pursuant to
         clauses 3.5(b), 8.2(b) or 10.3 above, and in the event that, but for
         the limitation of [*] on such reimbursement provided by such clause,
         such reimbursement would have exceeded, in respect of any Batch, [*]
         (notwithstanding that as a consequence of such limitation, such
         reimbursement did not exceed [*]), the parties shall meet in good faith
         to discuss amending such limitation retroactively such that, in the
         event that the parties agree on such an amendment, Chesapeake will
         reimburse Protherics a sum greater than [*], provided that the loss in
         respect of which such reimbursement is made arises as a consequence of
         any:

         (a)      cross contamination of any Bulk Product or Finished Product;

         (b)      failure of any freeze-drier during the drying cycle of the
                  Manufacture of any Batch;

         (c)      non-sterility of any part of the Facility which is required by
                  this agreement (including without limitation the Technical
                  Agreement) or by any Regulatory Authority to be sterile;

         (d)      withholding or withdrawal by the FDA of its approval of any
                  programme the subject of clause 10 of the Technical Agreement,
                  or Chesapeake's failure properly to implement or adhere to any
                  such programme or otherwise to comply with any of the
                  requirements of such clause; or

         (e)      failure properly to segregate Vials from different Batches.

13.      EXPERT DETERMINATION

13.1     In the event of a dispute or difference arising out of or relating to
         the Technical Agreement, the Specification or any technical issue,
         either party may notify the other in writing of the dispute or
         difference (the "DISPUTE NOTICE") together with reasonable details of
         such dispute or difference, whereupon the parties shall endeavour to
         resolve all matters in dispute as soon as practicable.

13.2     In the event of the parties' failing to resolve such matters within
         twenty (20) Business Days of service of the Dispute Notice, either
         party may refer the dispute or difference for determination to an
         Expert, who shall be appointed by agreement of the parries or, in
         default

* Material has been omitted pursuant to a request for confidential treatment
  and has been filed separately with the Commission.


                                      -23-


<PAGE>



         of agreement on such appointment within thirty (30) Business Days of
         the service of the Dispute Notice, on the application of either party,
         to an independent testing organisation chosen by Protherics, provided
         the same is acceptable to Chesapeake, such acceptance not to be
         unreasonably withheld or delayed.

13.3     In making such determination the Expert shall act as an expert and not
         as an arbitrator and his decision shall (in the absence of manifest
         error (and the Expert shall give reasons for his determination)) be
         final and binding on the parties.

13.4     Each party shall bear the costs and expenses of all counsel and other
         advisers, witnesses and employees retained by it and the costs and
         expenses of the Expert shall be borne by the parties in the proportions
         he may direct or, in the absence of direction, equally.

13.5     Subject to any rule of law or of any regulatory body or any provision
         of any contract or arrangement entered into prior to the date of this
         agreement to the contrary, the parties shall afford as soon as
         reasonably practicable upon request to the other and their respective
         agents and to the Expert, all facilities and access to their respective
         premises, personal papers, books, accounts, records, returns and other
         documents as may be in their respective possession or under their
         respective control as may be required by the Expert to make his
         determination.

13.6     For the avoidance of doubt, this clause 13 shall not operate to lessen
         Protherics' rights under clause 10 above.

14.      FORCE MAJEURE

14.1     "EVENT OF FORCE MAJEURE" means, in relation to either party, an event
         or circumstance beyond the reasonable control of that party (the
         "CLAIMING PARTY") including, without limitation, strikes, lock-outs and
         other industrial disputes (in each case, whether or not relating to the
         Claiming Party's workforce).

14.2     The Claiming Party shall not be deemed to be in breach of this
         agreement or otherwise liable to the other party (the "NON-CLAIMING
         PARTY") for any delay in performance or any non-performance of any
         obligations under this agreement (and the time for performance shall be
         extended accordingly) to the extent that the delay or non-performance
         is due to an Event of Force Majeure provided that:-

         (a)      the Claiming Party could not have avoided the effect of the
                  Event of Force Majeure by taking precautions which, having
                  regard to all matters known to it before the occurrence of the
                  Event of Force Majeure and all relevant factors, it ought
                  reasonably to have taken but did not take; and

         (b)      the Claiming Party has used reasonable endeavours to mitigate
                  the effect of the Event of Force Majeure and to carry out its
                  obligations under this agreement in any other way that is
                  reasonably practicable.

14.3     The Claiming Party shall promptly notify the Non-Claiming Party of the
         nature and extent of the circumstances giving rise to the Event of
         Force Majeure.





                                      -24-


<PAGE>



14.4     If the Event of Force Majeure in question prevails for a continuous
         period in excess of six (6) months after the date on which it began,
         the Non-Claiming Party may give notice to the Claiming Party
         terminating this agreement. The notice to terminate must specify the
         termination date, which must not be less than twenty five (25) Business
         Days clear days after the date on which the notice to terminate is
         given. Once the notice to terminate has been validly given, this
         agreement will terminate on the termination date set out in the notice.
         Neither party shall have any liability to the other in respect of
         termination of this agreement due to an Event of Force Majeure, but
         rights and liabilities which have accrued prior to termination shall
         subsist including without limitation those under clause 16.

15.      DURATION AND TERMINATION

15.1     (a)      This agreement shall come into effect on the date hereof and
                  shall continue in force for a period of [*] (the "INITIAL
                  TERM"), unless terminated earlier pursuant to this clause 15
                  or clauses 6.1(b), 8.4, 8.7, 9.5(d) or 14.4.

         (b)      Following the expiry of the Initial Term, and provided that
                  neither party has given the other notice of termination, such
                  notice to be given, if given by Protherics, at least twelve
                  (12) months prior to the end of the Initial Term and if given
                  by Chesapeake, at least twenty four (24) months prior to the
                  end of the Initial Term, this agreement shall remain in force
                  until terminated by either party giving to the other not less
                  than the respective aforementioned periods of written notice
                  unless otherwise terminated pursuant to this clause 15 or
                  clauses 6.1(b), 8.4, 8.7, 9.5(d) or 14.4.

15.2     This agreement shall terminate in the event that Protherics ceases the
         business of selling Finished Products, provided however that in such
         circumstances Protherics shall give Chesapeake six (6) months' notice
         of its intention to cease such business.

15.3     A party (the "INITIATING PARTY") may terminate this agreement with
         immediate effect by written notice to the other party (the "BREACHING
         PARTY"), on or at any time after the occurrence of any of the following
         events:

         (a)      the Breaching Party being in breach of a material obligation
                  under this agreement and, if the breach is capable of remedy,
                  failing to remedy the breach within twenty five (25) Business
                  Days starting on the day after receipt of written notice from
                  the Initiating Party giving full details of the breach and
                  requiring the Breaching Party to remedy the breach;

         (b)      the Breaching Party passing a resolution for its winding-up or
                  a court of competent jurisdiction making an order for the
                  Breaching Party's winding-up or dissolution;

         (c)      the making of an administration order in relation to the
                  Breaching Party or the appointment of a receiver over, or an
                  encumbrancer taking possession of or selling, an asset of the
                  Breaching Party;

         (d)      the Breaching Party making an arrangement or composition with
                  its creditors generally or making an application to a court of
                  competent jurisdiction for protection from its creditors
                  generally; and


* Material has been omitted pursuant to a request for confidential treatment
  and has been filed separately with the Commission.


                                      -25-

<PAGE>



         (e)      a change of control of the Breaching Party;

         or the equivalent of any of the events specified in clauses 15.3(c) to
         (d) in any relevant jurisdiction.

15.4     For the purpose of clause 15.3(a) above, a breach will be considered
         capable of remedy if time is not of the essence in performance of the
         obligation in question and if the Breaching Party can comply with the
         obligation within the twenty five (25) Business Days period referred to
         in clause 15.3(a).

15.5     Notwithstanding the above, Protherics may terminate this agreement
         forthwith and without liability to Chesapeake in the event that:

         (a)      Protherics receives notification that the FDA will not grant
                  its approval to Chesapeake Manufacturing Finished Products on
                  the licence granted to Protherics by the FDA concerning
                  Finished Products;

         (b)      Protherics does not receive such approval within a reasonable
                  time following the Effective Date;

         (c)      such approval, if granted, is withdrawn; or

         (d)      Protherics determines in its reasonable discretion not to
                  request such approval on the basis that it does not reasonably
                  consider that the FDA will grant the same.

15.6     In the event of the termination of this agreement, other than pursuant
         to clause 14.4 above, Chesapeake shall, notwithstanding such
         termination, Manufacture, store and deliver all Finished Products and
         provide Protherics with all documentation and information in respect
         thereof, the Manufacture of which Finished Products Protherics has
         ordered in accordance herewith prior to such termination, in accordance
         with the terms and subject to the conditions of this agreement
         including without limitation the relevant provisions of clauses 2, 4, 5
         and 8 above, and, notwithstanding such termination, the provisions of
         clause 3 above shall apply to all Bulk Products supplied by Protherics
         to Chesapeake, which are relevant to such Manufacture.

15.7     Notwithstanding the termination of this agreement for whatever reason,
         clauses 1, 2.13, 7.1 - 7.2, 7.4, 7.5, 7.7 - 7.9, 10 -14 and 17 - 27,
         and, in accordance with clause 16.5, clause 16, shall remain in full
         force and effect.

16.      CONFIDENTIALITY

16.1     As used in this agreement, the term "CONFIDENTIAL INFORMATION" means
         any technical or business information furnished by one party (the
         "DISCLOSING PARTY") to the other party (the "RECEIVING PARTY") in
         connection with this agreement or the parties' obligations hereunder,
         having the nature of confidentiality. Such Confidential Information may
         include, without limitation, trade secrets, know-how, inventions,
         technical data or specifications, testing methods, Business
         Information, Product Information, financial information, research and
         development activities, regulatory data, product and marketing plans,
         customer and supplier information and such information as may be
         provided by either party to the other pursuant to


                                      -26-




<PAGE>



          the provisions of clause 7. Confidential Information that is disclosed
          orally or visually shall be documented in a written notice prepared by
          the Disclosing Party and delivered to the Receiving Party within
          twenty five (25) Business Days of disclosure; such notice shall
          summarise the Confidential Information disclosed to the Receiving
          Party and reference the time and place of disclosure.

16.2      The Receiving Party agrees that it shall:-

         (a)      maintain all Confidential Information in strict confidence,
                  except that the Receiving Party may disclose or permit the
                  disclosure of any Confidential Information to its directors,
                  officers, employees, consultants and advisors, who are
                  obligated to maintain the confidential nature of such
                  Confidential Information, for the purposes set forth in this
                  agreement;

         (b)      use all Confidential Information solely for the purposes set
                  forth in this agreement or as otherwise authorised by this
                  agreement;

         (c)      allow its directors, officers, employees, consultants and
                  advisors to reproduce the Confidential Information only to the
                  extent necessary to effect the purposes set forth in this
                  agreement or as otherwise authorised by this agreement, with
                  all such reproductions being considered Confidential
                  Information.

16.3     The obligation set out in clause 16.2 above shall not apply to the
         extent that the Receiving Party can demonstrate that the relevant
         Confidential Information:-

         (a)      was in the public domain prior to the time of its disclosure
                  under this agreement;

         (b)      entered the public domain after the time of its disclosure
                  under this agreement through means other than an unauthorised
                  disclosure resulting from an act or omission of the Receiving
                  Party;

         (c)      was subsequently disclosed to the Receiving Party without any
                  obligation of confidence by a third party provided that such
                  third party was acting lawfully and not in breach of any duty
                  of confidence;

         (d)      is required to be disclosed to comply with applicable laws or
                  regulations, or with a court or administrative order, provided
                  that the Disclosing Party takes all reasonable and lawful
                  actions to obtain confidential treatment for such disclosure
                  and, if possible, to minimise the extent of such disclosure.

16.4     Following the termination of this agreement, the Receiving Party shall
         return to the Disclosing Party all originals, copies and summaries of
         documents, materials and other manifestations of Confidential
         Information, whether tangible or stored on computer, in the possession
         or control of the Receiving Party save that either party may retain one
         copy of any such Confidential Information if required to do so under
         any regulatory or legal requirement.

16.5     The obligations set forth in this clause shall survive for a period of
         10 years following termination of this agreement.




                                      -27-

<PAGE>
17.      INTELLECTUAL PROPERTY

17.1     Except as expressly set out in clause 5.4 above, nothing in this
         agreement shall affect or grant any right to any Intellectual Property
         Rights owned by the parties prior to the commencement of this
         agreement. In particular, Protherics shall remain solely entitled to
         all Intellectual Property Rights in the Bulk Products and the Finished
         Products, which entitlement shall not be affected in any way by this
         agreement and Chesapeake's right to use Protherics' trade marks shall
         be solely as specified in clause 5.4 above.

17.2     All Intellectual Property Rights which may arise in any documents,
         drawings, items, designs, processes, software or any other thing
         (collectively known as "IMPROVEMENT IP RIGHTS") developed by Chesapeake
         or any of its employees or agents in performance of this agreement
         shall vest in Chesapeake.

17.3     Chesapeake shall consider favourably any request made by Protherics (or
         an Affiliate of Protherics) to licence the Improvement IP Rights or any
         of them to a third party contract manufacturer to be engaged by
         Protherics or an Affiliate of Protherics, and shall not unreasonably
         withhold or delay its consent to such a licence being granted on
         reasonable commercial terms.

17.4     Protherics shall be responsible, at its expense, for obtaining on
         behalf of Chesapeake all necessary consents in respect of the use of
         any third party Intellectual Property Rights in information provided by
         Protherics necessary for the performance of Chesapeake's obligations
         under this agreement through utilising such information.

18.      COSTS

         Save as expressly otherwise provided in this agreement each of the
         parties shall bear its own legal, accountancy and other costs, charges
         and expenses connected with the negotiation, preparation and
         implementation of this agreement and any other agreement incidental to
         or referred to in this agreement.

19.      VARIATIONS

         This agreement may be varied only by a document signed by each of the
         parties.

20.      WAIVER

20.1     A waiver of any term, provision or condition of, or consent granted
         under, this agreement shall be effective only if given in writing and
         signed by the waiving or consenting party and then only in the instance
         and for the purpose for which it is given.

20.2     No failure or delay on the part of either party in exercising any
         right, power or privilege under this agreement shall operate as a
         waiver thereof, nor shall any single or partial exercise of any such
         right, power or privilege preclude any other or further exercise
         thereof or the exercise of any other right, power or privilege.

20.3     No breach of any provision of this agreement shall be waived or
         discharged except with the express written consent of the parties.


                                      -28-



<PAGE>



20.4     The rights and remedies herein provided are cumulative with and not
         exclusive of any rights or remedies provided by law.

21.      INVALIDITY

         If any provision of this agreement is or becomes (whether or not
         pursuant to any judgment or otherwise) invalid, illegal or
         unenforceable in any respect under the law of any jurisdiction:-

         (a)      the validity, legality and enforceability under the law of
                  that jurisdiction of any other provision; and

         (b)      the validity, legality and enforceability under the law of any
                  other jurisdiction of that or any other provision,

         shall not be affected or impaired in any way thereby.

22.      NOTICES

22.1     Any notice, demand or other communication given or made under or in
         connection with the matters contemplated by this agreement shall be in
         writing and shall be delivered personally or sent by fax or prepaid
         first class post (air mail if posted to or from a place outside the
         United Kingdom):-

          In the case of Protherics to:
          Blaenwaun,
          Ffostrasol,
          Llandysul,
          Ceredigion SA44 5JT,
          UK
          Fax: +44 (0)1239 858 800
          Attention: Company Secretary

          In the case of Chesapeake to:
          Camden Industrial Park,
          1111 S. Paca Street,
          Baltimore,
          M.D. 21230-2591,
          USA
          Fax:+1 410 843 4414
          Attention: The President

          and shall be deemed to have been duly given or made as follows:-

         (a)      if personally delivered, upon delivery at the address of the
                  relevant party;

         (b)      if sent by first class post, two Business Days after the date
                  of posting;

         (c)      if sent by air mail, five (5) Business Days after the date of
                  posting; and


                                      -29-



<PAGE>



         (d)      if sent by fax, when despatched;

         provided that if, in accordance with the above provision, any such
         notice, demand or other communication would otherwise be deemed to be
         given or made after 5.00 p.m. in the recipient's time zone such notice,
         demand or other communication shall be deemed to be given or made at
         the start of working hours on the next Business Day.

22.2     A party may notify the other party to this agreement of a change to its
         name, relevant addressee, address or fax number for the purposes of
         clause 22.1 provided that such notification shall only be effective
         on:-

         (a)      the date specified in the notification as the date on which
                  the change is to take place; or

         (b)      if no date is specified or the date specified is less than
                  five (5) Business Days after the date on which notice is
                  given, the date falling five (5) Business Days after notice of
                  any such change has been given.

23.      NO PARTNERSHIP

23.1     Nothing in this agreement and no action taken by the parties pursuant
         to this agreement shall constitute, or be deemed to constitute, the
         parties a partnership, association, joint venture or other co-operative
         entity.

23.2     At no time shall either of the parties have the authority to hold
         itself out as the agent of the other or as being empowered to bind the
         other in any way whether contractually or otherwise.

24.      ASSIGNMENT AND SUB-CONTRACTING

24.1     Neither party may, without the prior written consent of the other,
         assign the benefit of all or any of the other party's obligations under
         this agreement, nor any benefit arising under or out of this agreement.

24.2     Chesapeake may sub-contract any of its obligations under this
         agreement, provided that:

         (a)      it has used all due diligence in selecting the third party to
                  which it sub-contracts such obligations, by evaluating the
                  competency of such third party to undertake the same;

         (b)      it advises Protherics in advance of its intention to
                  sub-contract such obligations to a third party and at such
                  time identifies such third party to Protherics and informs
                  Protherics of the terms of such proposed sub-contracting
                  arrangement; and

         (c)      Protherics consents in writing to such sub-contracting to such
                  party on such terms, which consent may be withheld for any
                  reason.

24.3     Notwithstanding any sub-contracting of its obligations to a third
         party, Chesapeake shall remain fully responsible for the performance of
         its obligations under this agreement and fully liable for any breach
         thereof.




                                      -30-


<PAGE>



24.4     In the event that Chesapeake sub-contracts any of its obligations under
         this agreement to a third party, Chesapeake shall conduct audits of
         such third party's performance on at least an annual basis and promptly
         report the results of such audits to Protherics, and, in the event that
         such audits reveal any non- or mal-performance by such third party of
         such sub-contracted obligations, Chesapeake shall immediately terminate
         such sub-contracting arrangement.

24.5     Protherics shall be entitled, at will and upon reasonable notice, to
         undertake cGMP audits of any third party to which Chesapeake
         sub-contracts any or all of its obligations under this agreement and
         Chesapeake shall ensure that such third party consents and submits to
         such entitlement.

25.      GOVERNING LAW AND JURISDICTION

25.1     This agreement (and any dispute, controversy, proceedings or claims of
         whatever nature arising out of or in any way relating to this agreement
         or its formation) shall be governed by and construed in accordance with
         English law.

25.2     Each of the parties to this agreement irrevocably agrees that the
         courts of England and Wales shall have exclusive jurisdiction to hear
         and decide any suit, action or proceedings, and/or to settle any
         disputes, which may arise out of or in connection with this agreement
         and, for these purposes, each party irrevocably submits to the
         jurisdiction of the courts of England and Wales.

26.      EXCLUSION OF THIRD PARTY RIGHTS

         The Contracts (Rights of Third Parties) Act 1999 shall not apply to
         this agreement and no rights or benefits expressly or impliedly
         conferred by it shall be enforceable under that Act against the parties
         to it by any other person.

27.      ENTIRE AGREEMENT

27.1     Subject to clause 27.3, this agreement constitutes the entire and only
         agreement between the parties relating to the subject matter hereof and
         neither party has been induced to enter into this agreement in reliance
         upon, nor has either party been given, any warranty, representation,
         statement, assurance, covenant, agreement, undertaking, indemnity or
         commitment of any nature whatsoever other than as are expressly set out
         herein and, to the extent that any of them has been, it unconditionally
         and irrevocably waives any claims, rights or remedies which it might
         otherwise have had in relation thereto.

27.2     Subject to clause 27.3, neither party has any right to rescind or
         terminate this agreement either for breach of contract or for negligent
         or innocent misrepresentation or otherwise.

27.3     The provisions of this clause 27 shall not exclude any liability which
         either party would otherwise have to the other party or any right which
         either of them may have in respect of any statements made fraudulently
         by either of them prior to the execution of this agreement or any
         rights which either of them may have in respect of fraudulent
         concealment by the other.

IN WITNESS whereof this agreement has been executed on the date first above
written.




                                      -31-

<PAGE>
Signed by
a duly authorised representative of PROTHERICS UK LIMITED


/s/ James C. Christie
----------------------------------(Signature)
JAMES C. CHRISTIE



Signed by
a duly authorised representative of CHESAPEAKE BIOLOGICAL LABORATORIES INC.




/s/ John Boter
----------------------------------(Signature)
JOHN BOTER


                                      -46-