<Page>

                            ISIS PHARMACEUTICALS INC


                           ANTISENSE THERAPEUTICS LTD





                            STOCK PURCHASE AGREEMENT

                                 MINTER ELLISON
                                     Lawyers
                                  Rialto Towers
                               525 Collins Street
                             MELBOURNE VIC 3000

                                DX 204 Melbourne
                          Telephone (03) 8608 2000
                          Facsimile (03) 8608 1000

                                       JJS


<Page>

                            STOCK PURCHASE AGREEMENT


This Stock Purchase Agreement (the "Agreement") between ISIS PHARMACEUTICALS,
INC. of 2292 Faraday Avenue, Carlsbad, CA 92008, USA ("ISIS") and ANTISENSE
THERAPEUTICS LTD., ACN 095 060 745 of Level 1, 10 Wallace Avenue, Toorak,
Victoria 3142, AUSTRALIA ("ATL") is entered into and made effective in
accordance with the provisions of the agreement entitled "Master Agreement"
between ATL and ISIS, dated October 30, 2001. The effective date of this
Stock Purchase Agreement will be the date upon which conditions 1 and 3 in
the Master Agreement have been met (the "Effective Date"). If the Effective
Date has not occurred by March 28, 2002, this Agreement will be null and void
and will not become effective.

RECITALS

A.      The parties intend to enter into a Collaboration and Licence
        Agreement dated 30 October 2001 ('COLLABORATION AND LICENCE
        AGREEMENT').

B.      Under that Agreement Isis will licence intellectual property to ATL
        on the terms and conditions of the Collaboration and Licence
        Agreement.

C.      ATL has agreed to issue and grant to Isis, and Isis has agreed to
        subscribe for, shares and options in the capital of ATL on the terms
        and conditions of this Stock Purchase Agreement.

AGREEMENT

1.      DEFINITIONS

        In this agreement, unless the contrary intention appears:

        'ASX' means Australian Stock Exchange Limited ACN 008 624 691.

        'ASX LISTING' means admission of ATL to the ASX Official List and
        quotation by the ASX of shares in ATL.

        'ASX LISTING RULES' means the listing rules of the ASX as amended
        from time to time.

        'ATL SHARES' means fully paid ordinary shares in ATL.

        'BUSINESS DAY' means the day in which banks (as defined under the
        Banking Act 1959 (Cth)) are open for general banking business in
        Victoria, Australia excluding Saturdays and Sundays.

        'CIRCADIAN' means Circadian Technologies Limited ACN 006 340 567 of
        Level 1, 10 Wallace Avenue, Toorak, Victoria 3142, Australia.

        'COMPLETION' means completion of the subscription for, and issue of,
        the ATL Shares in accordance with clause 6.

        'COMPLETION DATE' means the date 2 Business Days after the ASX has
        approved of the ASX Listing of ATL and ATL has satisfied all
        conditions attaching to such approval, or such other date as the
        parties may agree in writing.


                                      2

<Page>

        'MURDOCH INSTITUTE' means the Murdoch Childrens Research Institute of
        Parkville, Victoria, Australia.

        'MURDOCH INTERESTS' means the Murdoch Institute or other party
        nominated by the Murdoch Institute.

        'OPTION' means an option to acquire by way of issue 1 ATL Share on
        the following terms:

        (a)    the exercise price for each option is 20 Australian cents per
               share;

        (b)    the exercise period will be the period commencing on the date
               of grant of the option and ending on 30 November 2006;

        (c)    such other terms as are set out in schedule 1 or as otherwise
               required by ASX.

        'RECORD DATE' means a date proximate to the date of ASX listing to be
        determined in accordance with ASX requirements.

        'RESTRICTION AGREEMENT' means the restriction agreement set out in
        Appendix 9A to the ASX Listing Rules as applies at Completion, the
        form of which (as at 3 September 2001) is set out in schedule 2.

        'POLYCHIP' means Polychip Pharmaceuticals Pty Ltd ACN 006 455 456 of
        Level 1, 10 Wallace Avenue, Toorak, Victoria, 3142, Australia, a
        wholly owned subsidiary of Circadian.

        'SUBSCRIPTION SHARES' means 30 million fully paid ordinary shares in
        ATL.

        'SYNGENE' means Syngene Ltd ACN 006 161 753 of Level 1, 10 Wallace
        Avenue, Toorak, Victoria, 3142, Australia, a company in which
        Polychip has a minority shareholding.

2.      CONDITION

2.1     CONDITION

        The provisions of clauses 3, 4 and 6 have no effect and the issue of
        the ATL Shares, and grant of the Options by ATL to Isis as
        contemplated by clause 3 of this agreement shall not occur, unless
        and until the following condition is satisfied (the 'Condition'):

               ASX approves an ASX Listing of ATL and ATL satisfies all
               conditions attaching to such approval (other than the issue of
               shares and grant of options to Isis, as contemplated by clause
               3), in each case on or before 26 March 2002 or such later date
               as the parties may agree in writing.

2.2     WAIVER OF CONDITION

        The Condition may not be waived except by a waiver in writing signed
        by each party and will be effective only to the extent specifically
        set out in that waiver.

2.3     CONDUCT OF THE PARTIES

        Each party must use its reasonable efforts within its own capacity to
        ensure that the Condition is satisfied.


                                      3

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2.4     FAILURE OF CONDITION

        (a)    Either party may terminate this agreement by giving notice in
               writing to the other party at any time before Completion if the
               Condition is not satisfied, or waived by each party, before 5.00
               pm on the Business Day immediately before the date set out in
               the Condition or such later date as may be agreed in writing by
               the parties.

3.      ISSUE OF SHARES AND GRANT OF OPTIONS

3.1     AGREEMENT TO ISSUE SHARES AND GRANT OPTIONS

        On and subject to the terms and conditions of this agreement:

        (a)    Isis agrees to subscribe for, and ATL agrees to issue to
               Isis, the Subscription Shares; and

        (b)    ATL agrees to grant to Isis 20 million Options.

3.2     ACKNOWLEDGMENT

        The parties acknowledge that:

        (a)    ATL will be capitalised by various shareholders prior to the ASX
               Listing of ATL on the basis set out below:

<Table>
<Caption>
               ----------------------------------------------------------------
                           ENTITY                   NUMBER OF ATL SHARES
               ----------------------------------------------------------------
               <S>                                  <C>
               Polychip                                54.375 million
               ----------------------------------------------------------------
               Syngene                                 54.375 million
               ----------------------------------------------------------------
               Murdoch Interests                       11.250 million
               ----------------------------------------------------------------
               Total                                     120 million
               ----------------------------------------------------------------
</Table>
        (b)    It is anticipated that, after the ASX Listing of ATL, ATL
               will:

               (i)    be capitalised as to approximately 190 million to
                      215 million ATL Shares; and

               (ii)   have granted between 105 million Options and 117.5
                      million Options.

        (c)    It is intended that ATL Shares will be offered to the public for
               a subscription price of 20 Australian cents per ATL Share, with
               a free Option attaching to each ATL Share at the rate of 1
               Option for every 2 ATL Shares issued.

        (d)    It is intended that, after the ASX Listing of ATL, the ATL
               Shares issued and Options granted by ATL will be as follows:

<Table>
<Caption>
               ----------------------------------------------------------------
                       PARTY          NUMBER OF ATL SHARES  NUMBER OF OPTIONS
               ----------------------------------------------------------------
               <S>                    <C>                   <C>
               Polychip                  54.375 million
               ----------------------------------------------------------------
               Syngene                   54.375 million
               ----------------------------------------------------------------
               Murdoch Interests         11.250 million
               ----------------------------------------------------------------
</Table>


                                      4

<Page>


<Table>
               <S>                    <C>                   <C>
               ----------------------------------------------------------------
               Isis                        30 million           20 million
               ----------------------------------------------------------------
               Public Subscribers       40 to 65 million    20 to 32.5 million

               Circadian                                        42 million
               Shareholders*
               ----------------------------------------------------------------
               Syngene Shareholders*                            23 million
               ----------------------------------------------------------------
               TOTAL**                 190 TO 215 MILLION   105 TO 117.5 MILLION**
               ----------------------------------------------------------------
</Table>

               *The number of Options to be granted to Circadian Shareholders
               and Syngene Shareholders respectively are approximate only, based
               on the issued capital of each of Circadian and Syngene as at the
               Record Date. It is intended that those shareholders will be
               issued Options on the basis of 1 Option for every share held by
               the shareholders in Circadian and Syngene (as the case may be) on
               payment to ATL of 1 cent per Option. The Isis and Public Options
               will be free.

               **This total will be increased by any options granted pursuant to
               the share option scheme described in clause 3.2(e).

        (e)    ATL intends putting in place a share option scheme in which
               senior originators inventors, employees and directors will
               participate.  These options will have the same terms and
               conditions as the Options to be granted to the public under
               the prospectus, except it is intended there will be
               additional vesting conditions which will provide for gradual
               vesting for up to 5 years, restrictions on transfer and
               conditions on continued employment or involvement in ATL's
               projects.  It is currently intended that the following
               entitlements will be granted under that scheme:

<Table>
<Caption>
               -----------------------------------------------------------------
                            INDIVIDUAL                     NUMBER OF OPTIONS
               -----------------------------------------------------------------
               <S>                                       <C>
               Stanley Crooke (Non-executive Director)       2 million

               -----------------------------------------------------------------
               Chris Belyea (Managing Director and           2 million
               Originator)
               -----------------------------------------------------------------
               George Tachas (Research Director (non-       1.5 million
               Board position), inventor and Originator)
               -----------------------------------------------------------------
               Christopher Wraight (inventor)                2 million
               -----------------------------------------------------------------
               George Werther (inventor)                     2 million
               -----------------------------------------------------------------
               other Directors of ATL                    to be determined by ATL
               -----------------------------------------------------------------
               other Executives/Scientists               to be determined by ATL
               ----------------------------------------------------------------
</Table>

4.      CONSIDERATION

        The parties acknowledge and agree that the consideration to be
        provided by Isis to ATL for the Subscription Shares and Options to be
        granted under clause 3 is the grant of the licences and provisions of
        the other services provided by Isis pursuant to the Collaboration and
        Licence Agreement.

5.      ASX RESTRICTION AGREEMENT

5.1     The parties acknowledge that the ATL Shares and Options to be held by
        Polychip, Syngene, Murdoch Interests and Isis are likely to be
        regarded by the ASX as restricted securities for the purposes of the
        Chapter 9 of the ASX Listing Rules, to be placed in


                                      5

<Page>

        escrow for a period of 2 years. Isis must sign a Restriction
        Agreement (and Isis must procure any controller (as that term is
        defined in the ASX Listing Rules) to sign a Restriction Agreement) in
        the form required by ASX and forward such documents (together with
        any other documents required under that agreement) to ATL within 2
        Business Days of being requested in writing by ATL to do so for the
        purposes of facilitating the proposed ASX Listing of ATL.

6.      COMPLETION

6.1     TIME AND PLACE

        Completion will take place on the Completion Date at the office of
        Minter Ellison, Lawyers at Level 23, Rialto Towers, 525 Collins
        Street, Melbourne, Victoria, Australia or another place agreed by the
        parties.

6.2     SIMULTANEOUS ACTIONS AT COMPLETION

        All actions at Completion will be treated as taking place
        simultaneously and no delivery will be regarded as having been made
        until all deliveries due to be made by Completion have been made.

6.3     OBLIGATIONS OF ISIS

        At or before Completion, Isis must do all of the things listed below:

        (a)    provide to ATL a Restriction Agreement duly signed by Isis and
               any controller of Isis (as defined by the ASX Listing Rules) in
               accordance with clause 5;

        (b)    provide to ATL all such other documents as are required
               pursuant to the terms of the Restriction Agreement;

        (c)    provide to ATL an application for the ATL Shares to be
               subscribed for by Isis pursuant to clause 3.1;

        (d)    provide to ATL an application for Options to be granted to
               Isis pursuant to clause 3.1.

6.4     OBLIGATIONS OF ATL

        At Completion, ATL must, subject to compliance by Isis with the
        provisions of clause 6.3, issue to Isis the Subscription Shares and the
        Options to be granted pursuant to clause 3.1.

6.5     WAIVER

        If any of the obligations set out in clauses 6.3 and 6.4 above are
        not complied with in any respect on the date set for Completion, the
        other party may in its absolute discretion:

        (a)    waiver compliance with that provision;

        (b)    defer Completion to a date not more than 5 Business Days
               after the date set for Completion;

        (c)    proceed to Completion as far as its practicable (without
               prejudice to any of its rights under this agreement); or


                                      6

<Page>

        (d)    terminate this agreement by notice in writing to the other
               party.

6.6     ACCRUED RIGHTS

        Termination of this agreement does not affect any accrued rights or
        remedies of a party.

7.      ASSIGNMENT

        A party may not assign any of its rights under this agreement without
        the consent of the other parties.

8.      WAIVER

8.1     WAIVER

        A provision of or right under this agreement may not be waived except
        by a waiver in writing signed by the party granting the waiver, and
        will be effective only to the extent specifically set out in that
        waiver.

8.2     RIGHTS EXERCISABLE

        The failure of a party at any time to require performance of any
        obligation under this agreement is not a waiver of that party's right:

        (a)    to insist on performance of, or claim damages for breach of,
               that obligation unless that party acknowledges in writing that
               the failure is a waiver; and

        (b)    at any other time to require performance of that or any other
               obligation under this agreement.

9.      NOTICES

9.1     SERVICE OF NOTICES

        A party giving or serving notice or notifying under this agreement
        must do so in writing:

        (a)    directed to the recipient's address specified in this
               clause, as varied by any notice; and

        (b)    hand delivered or sent by prepaid post or facsimile to that
               address.

        The parties' addresses and facsimile numbers are:

        Isis Pharmaceuticals, Inc
        2292 Faraday Avenue
        Carlsbad, CA 92008
        United States of America
        Facsimile No:  +1 760 931 9639

        Antisense Therapeutics Ltd
        Level 1, 10 Wallace Avenue
        Toorak, Victoria 3000
        Australia
        Facsimile No:  +61 3 9824 0083


                                      7

<Page>

9.2     DEEMED RECEIPT

        A notice given in accordance with clause 9.1 is taken to be received:

        (a)    if hand delivered, on delivery;

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

        (c)    if sent by facsimile, when the sender's facsimile system
               generates a message confirming successful transmission of the
               total number of pages of the notice unless, within one Business
               Day after the transmission, the recipient informs the sender
               that it has not received the entire notice.

9.3     EXECUTION

        A notice given in accordance with clause 9.1 is sufficiently signed
        for or on behalf of a party if:

        (a)    in the case of a company, it is signed by a director,
               secretary or other officer of the company; or

        (b)    in the case of an individual, it is signed by that party.

9.4     OTHER MODES OF SERVICE PERMITTED

        The provisions of this clause 9 are in addition to any other mode of
        service permitted by law.

10.     GOVERNING LAW AND JURISDICTION

        This agreement is governed by the law applicable in Victoria,
        Australia and each party irrevocably and unconditionally submits to
        the non-exclusive jurisdiction of the courts of Victoria, Australia.

11.     GENERAL

11.1    DURATION OF PROVISIONS

        On completion of the transactions contemplated in this agreement, the
        provisions of this agreement will not merge and, to the extent any
        provision has not been fulfilled, will remain in force.

11.2    FURTHER ACTION

        Each party must use reasonable efforts to do all things necessary or
        desirable to give full effect to this agreement.

11.3    COUNTERPARTS

        This agreement may be executed in any number of counterparts.

11.4    ALTERATIONS

        This agreement may be altered only in writing signed by each party.

11.5    COSTS


                                      8

<Page>

        Each party must bear its own costs of negotiating, preparing and
        executing this agreement.

11.6    ATTORNEYS

        Where this agreement is executed on behalf of a party by an attorney,
        that attorney by executing declares and warrants that the attorney
        has been duly appointed and has no notice of the revocation of the
        power of attorney under the authority of which the attorney executes
        the agreement on behalf of that party.

11.7    INTERPRETATION

        In this agreement, unless the contrary intention appears:

        (a)    headings are for ease of reference only and do not affect
               the meaning of this agreement;

        (b)    the singular includes the plural and vice versa and words
               importing a gender include other genders;

        (c)    other grammatical forms of defined words or expressions have
               corresponding meanings;

        (d)    a reference to a clause, paragraph, schedule, annexure or
               attachment is a reference to a clause or paragraph of or
               schedule, annexure or attachment to this agreement and a
               reference to this agreement includes its schedules, annexures
               and attachments;

        (e)    a reference to a document or agreement, including this
               agreement, includes a reference to that document or agreement as
               novated, altered or replaced from time to time;

        (f)    a reference to `A$', `$A', `dollar' or `$' is a reference to
               Australian currency;

        (g)    a reference to a specific time for the performance of an
               obligation is a reference to that time in Melbourne, Australia
               even if the obligation is to be performed elsewhere;

        (h)    a reference to a party includes a reference to the party's
               executors, administrators, successors, substitutes and
               assigns;

        (i)    words and expressions importing natural persons include
               partnerships, bodies corporate, associations, governments and
               governmental and local authorities and agencies, and vice versa;

        (j)    a reference to any legislation or statutory instrument or
               regulation is construed in accordance with the ACTS
               INTERPRETATION ACT 1901 (Cth) or the equivalent State
               legislation, as applicable;

        (k)    a reference to writing includes typewriting, printing,
               lithography, photography and any other method of representing or
               reproducing words, figures or symbols in a permanent and visible
               form;

        (l)    if a day for payment under this agreement falls on a day
               which is not a Business Day, payment is due on the next
               Business Day;


                                      9

<Page>

        (m)    if a provision of this agreement binds two or more parties
               (including any representation, warranty or indemnity given, made
               or undertaken by two or more parties), that provision binds (and
               that representation, warranty or indemnity is given, made or
               undertaken by) those parties jointly and severally; and

        (n)    if a party comprises two or more persons, the provisions of this
               agreement binding that party bind those persons jointly and
               severally.



EXECUTED as an agreement.

<Table>
<S>                                       <C>
ANTISENSE THERAPEUTICS, LIMITED           ISIS PHARMACEUTICALS, INC.



By:    /s/ C. Belyea                      By:     /s/ B. Lynne Parshall
   -------------------------------           ---------------------------------
Name:      C. BELYEA                      Name:       B. LYNNE PARSHALL
     -----------------------------             -------------------------------
Title:     CEO                               Title:   EXECUTIVE VICE PRESIDENT
      ----------------------------              ------------------------------
                                                AND CHIEF FINANCIAL OFFICER
                                                ------------------------------
</Table>

                                      10

<Page>

                SCHEDULE 1 - TERMS AND CONDITIONS OF OPTIONS


Each option ('OPTION') shall entitle the holder of the Option ('OPTION
HOLDER') to acquire by way of issue one fully paid ordinary share ('SHARE')
in Antisense Therapeutics Limited ('COMPANY') on the terms and conditions set
out below:

1.      Each Option is exercisable at any time after the date of grant to a
        date up to and including 30 November 2006.

2.      If the Option is not exercised on or prior to the expiry of the
        Option Period, the Option shall lapse.

3.      The Options may be exercised wholly or in part by giving notice in
        writing ('NOTICE OF EXERCISE') to the Board at any time during the
        Option Period.

4.      Options shall only be exercisable in multiples of 100. Within 10
        business days of the exercise of the Option the Company shall apply
        for the shares to be admitted for quotation on the Official List of
        Australian Stock Exchange Limited.

5.      The exercise price for each Option is $0.20 per share ('EXERCISE
        PRICE') and is payable immediately on exercise.

6.      On receipt by the Company of the Notice of Exercise and payment of
        the relevant Exercise Price, the Company must, within 14 days, issue
        to the Option Holder the number of Shares in respect of which the
        Option is exercised and despatch the relevant share certificate or
        other appropriate acknowledgment as soon as reasonably practicable
        thereafter.

7.      Shares issued on the exercise of any Options will rank equally in all
        respects with the then existing issued ordinary fully paid shares in
        the Company and will be subject to the provisions of the Constitution
        of the Company.

8.      An Option does not confer rights to participate in new issues of
        securities of the Company, unless the Option Holder has first
        exercised the Option.

9.      Adjustments to the number of shares over which Options exist and/or
        the Exercise Price will be made to take account of changes to the
        capital structure of the Company by way of pro rata bonus and cash
        issues as follows:

        (a)    Pro-Rata Cash issues

               Where a pro-rata issue is made (except a bonus issue) to the
               holders of underlying securities, the Exercise Price of an
               option may be reduced according to the following formula:

               O' =     O -   E[P-(S+D)]
                              ----------
                                N + 1
               where:
               O' =   the new exercise price of the option.
               O  =   the old exercise price of the option.
               E  =   the number of underlying securities into which one
                      option is Exercisable.
               P  =   the average Market Price per security (weighted by
                      reference to volume) of the underlying securities
                      immediately prior to the time of determining entitlements
                      to participate in the issue.


                                      11

<Page>

               S  =   the Subscription price for a security under the pro
                      rata issue.
               D  =   the Dividend due but not yet paid on the existing
                      underlying securities (except those to be issued
                      under the pro rata issue).
               N  =   the Number of securities with rights or entitlements
                      that must be held to receive a right to one new security.

        (b)    Pro-Rata Bonus Issues

               If there is a bonus issue to the holders of the underlying
               securities, on the exercise of any options, the number of shares
               received will include the number of bonus shares that would have
               been issued if the options had been exercised prior to the date
               established to determine entitlements to participate in the
               bonus issue. The Exercise Price will not change.

        (c)    For the purposes of the definition of 'P' in paragraph (a),
               'Market Price' in relation to a security means the arm's length
               value of the security as specified in a written report given to
               the Company by a person who is registered as a company auditor
               under a law in force in a State or a Territory and who is not a
               director, secretary or employee of the Company.

10.     In the event of any reorganisation (including consolidation,
        sub-division, reduction or return) of the issued capital of the
        Company, the rights of the Option Holder including the number of
        options or the Exercise Price or both shall be reorganised (as
        appropriate):

        (a)    in the event of a consolidation of the share capital of the
               Company, the number of options will be consolidated in the same
               ratio as the ordinary share capital of the Company and the
               Exercise Price will be amended in inverse proportion to that
               ratio;

        (b)    in the event of a subdivision of the share capital of the
               Company, the number of options will be subdivided in the same
               ratio as the ordinary share capital of the Company and the
               Exercise Price will be amended in inverse proportion to that
               ratio;

        (c)    in the event of a return of the share capital of the Company,
               the number of options will remain the same and the Exercise
               Price will be reduced by the same amount as the amount returned
               in relation to each ordinary share;

        (d)    in the event of a reduction of the share capital of the Company
               by a cancellation of paid up capital that is lost or not
               represented by available assets where no securities are
               cancelled the number of options and the Exercise Price of each
               option will remain unaltered;

        (e)    in the event of a pro rata cancellation of shares in the
               Company, the number of options will be reduced in the same
               ratio as the ordinary share capital of the Company and the
               Exercise Price of each option will be amended in inverse
               proportion to that ratio; and

        (f)    in the event of any other reorganisation of the issued capital
               of the Company, the number of options or the Exercise Price or
               both will be reorganised (as appropriate) in a manner which will
               not result in any benefits being conferred on Option Holders
               which are not conferred on shareholders.


                                      12

<Page>

11.     Notices may be given by the Company to the Option Holder in the
        manner prescribed by the Constitution of the Company for the giving
        of notices to the Shareholders of the Company and the relevant
        provisions of the Constitution of the Company will apply with all
        necessary modification to notices to be given to the Option Holder.

12.     The Option Holder will be sent all reports and accounts required to
        be laid before Shareholders in general meeting and all notices of
        general meeting of Shareholders, but he will not have any right to
        attend or vote at these meetings.


                                      13

<Page>

                       SCHEDULE 2 - RESTRICTION AGREEMENT


                                   APPENDIX 9A

                              RESTRICTION AGREEMENT

Introduced 1/7/96.  Origin:  Appendix 11.  Amended 1/7/98.

We, the persons in:

-     Item 1 of the schedule ("entity");

-     Item 2 of the schedule ("holder");

-     Item 3 of the schedule ("controller"),

agree as follows.


INTRODUCTION

A.      The entity wants to be listed and has issued restricted securities.
        The holder will hold the restricted securities as set out in this
        agreement on the basis that the entity will take the steps necessary
        to be admitted to the +official list of ASX.

B.      We have provided ASX with all the information necessary to properly
        form an opinion about who is a +controller of the holder and who is
        required to execute this agreement.

C.      We enter this agreement for the purpose of complying with chapter 9
        of the listing rules.

AGREEMENT

Escrow restrictions

1.    During the escrow period, the holder will not do any of the following.

        (a) +Dispose of, or agree or offer to +dispose of, the restricted
            securities.

        (b) Create, or agree or offer to create, any security interest in
            the restricted securities.

        (c) Do, or omit to do, any act if the act or omission would have the
            effect of transferring effective ownership or control of the
            restricted securities.

2.    During the escrow period, a controller will not do any of the following.

        (a) +Dispose of, or agree or offer to +dispose of, the controller
            interests.

        (b) Create, or agree or offer to create, any security interest in
            the controller interests.

        (c) Do, or omit to do, any act if the act or omission would have the
            effect of transferring effective ownership or control of the
            controller interests.


                                      14

<Page>

3.      We will comply with chapter 9 of the listing rules. If any of us is
        not a listed entity, we will comply as if we were a listed entity.
        Each of us will take any steps we are able to take that are necessary
        to enable any of the others to comply.

4.      The holder will deposit the certificates for the restricted
        securities with a bank or +recognised trustee for the escrow period.

Warranties

5.      If only the holder and the entity are parties to this agreement, one
        of the following applies.

        (a)    The holder is an individual.

        (b)    The holder has no +controller.

        (c)    The holder has the +controllers set out in item 3 with the
               interests identified in item 6, and each +controller comes
               within an exception set out in rule 9.1.4.

        The holder gives this warranty.

6.      If the holder, the entity and any +controller are parties to this
        agreement, the holder has the +controllers set out in item 3 with the
        controller interests identified in item 6, and any +controller who is
        not a party to this agreement comes within an exception set out in
        rule 9.1.4. The holder and each +controller give this warranty.

7.      If item 7 of the schedule is completed, the full particulars of
        security interests which have been created, or are agreed or offered
        to be created, in the restricted securities are set out. A release of
        the security interests is attached. Apart from this, before the
        escrow period begins, the holder has not done, or omitted to do, any
        act which would breach clause 1 if done or omitted during the escrow
        period. The holder gives this warranty.

8.      If item 8 of the schedule is completed, the full particulars of
        security interests which have been created, or are agreed or offered
        to be created, in the controller interests are set out.  A release of
        the security interests is attached.  Apart from this, before the
        escrow period begins, the +controller has not done, or omitted to do,
        any act which would breach clause 2 if done or omitted during the
        escrow period.  Each +controller gives this warranty.

9.      A breach of any of these warranties is a breach of this agreement.

Consequences of breaching this agreement

10.     If it appears to the entity that the holder or a +controller may
        breach this agreement, the entity must take the steps necessary to
        prevent the breach, or to enforce the agreement.

11.     If the holder or a +controller breach this agreement, each of the
        following applies.

        (a) The entity must take the steps necessary to enforce the agreement,
            or to rectify the breach.


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        (b) The entity must refuse to acknowledge, deal with, accept or
            register any sale, assignment, transfer or +conversion of any of
            the restricted securities. This is in addition to other rights and
            remedies of the entity.

        (c) The holder of the restricted securities ceases to be entitled to
            any dividends, distributions or voting rights while the breach
            continues.

Amendment

12.     This agreement will not be changed or waived without ASX's written
        consent.

Jurisdiction

13.     The laws of the State of the home branch of the entity apply to this
        agreement.  We submit to the jurisdiction of the courts of that State.

Definitions and interpretation

In this agreement:

ASX  means Australian Stock Exchange Limited.

CONTROLLER INTERESTS means the +securities, substantial economic interest or
other interests in the restricted securities and each intermediate entity
through which that interest occurs, full particulars of which are set out in
item 6 of the schedule.

ESCROW PERIOD  means the period set out in item 4 of the schedule.

RESTRICTED SECURITIES means the +securities set out in item 5 of the schedule
and any +securities attaching to or arising out of those +securities that are
restricted securities because of the definition of restricted securities in
the listing rules.

The singular includes the plural and vice versa.

A reference to a party includes its successors, personal representatives and
transferees.

Words and expressions defined in the listing rules of ASX, and not in this
agreement, have the meanings given to them in the listing rules.

Every warranty or agreement (expressed or implied) in which more than one
person joins, binds them individually and any combination of them as a group.

                                    Schedule

1.    Entity's name and address:

2.    Holder's name and address:

3.    Each +controllers' name and address:

4.    Escrow period (the date from which the initial restricted securities
      are escrowed):

5.    Particulars of restricted securities:


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6.    Particulars of controller interests:

7.    Particulars of security interests over restricted securities:

8.    Particulars of security interests over controller interests:

Dated:
[Proper execution as a deed]


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