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Exhibit 10.33

                                                               Execution Version

                               AMENDMENT NO. 1 TO
                         COMMON STOCK PURCHASE AGREEMENT

         This Amendment No. 1 to Common Stock Purchase Agreement (the
"Amendment") is made as of April 29, 2003, between PharmaNetics, Inc, a North
Carolina corporation (the "Company"), and Bayer Corporation, an Indiana
corporation (the "Purchaser").

                                    RECITALS

         WHEREAS, the Company and the Purchaser are parties to that certain
Common Stock Purchase Agreement dated as of April 23, 2001 (the "Common Stock
Purchase Agreement"); and

         WHEREAS, the Company and the Purchaser desire to amend the registration
rights and preemptive rights granted to the Purchaser pursuant to Sections 7.6
and 7.9, respectively, of the Common Stock Purchase Agreement and certain
restrictions on the transfer of Common Stock set forth in Section 8.6(b) of the
Common Stock Purchase Agreement.

         NOW, THEREFORE, in consideration of the premises and mutual covenants
set forth herein, and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

     Section 1.  Amendments to the Common Stock Purchase Agreement.

         1.1     Section 7.6 of the Common Stock Purchase Agreement is hereby
amended and restated in its entirety to read as follows:

         7.6     Registration Rights.

                 (a)   Demand Registration.

                       (i)   At any time on or after the date hereof, the
Covered Holders, provided the registration rights hereunder have not lapsed as
set forth in Section 7.6(i) hereof, may demand in writing that the Company
effect a registration under the Securities Act of all or any portion of the
Registrable Securities then outstanding. Without limiting the foregoing, so long
as the Company is S-3 Eligible, then the Covered Holders shall also have the
right, on not more than one occasion every six months, to require the Company to
register for offer and sale pursuant to a Registration Statement on Form S-3 if
so requested by a majority of the Covered Holders (which majority shall be
calculated based on the number of Registrable Securities held by all Covered
Holders) all or a portion of the Registrable Securities then outstanding with an
expected aggregate offering price of at least $1,000,000; provided, however,
that the Covered Holders may request registration of any amount of Registrable
Securities where the request relates to all remaining Registrable Securities for
the purpose of sale in the manner specified in such demand. Such demand shall
also specify the number of Registrable Securities that the Covered Holders wish
to have so registered. Each registration of Registrable Securities made pursuant
to this Subsection (i) shall be a "Demand Registration." The Company shall
prepare and file a registration statement on any available form of registration
statement (the "Demand

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                                                               Execution Version

Registration Statement"), for the public sale of the Registrable Securities as
soon as practicable; provided, however, that if the Company shall furnish to the
holders of Registrable Securities participating in a Demand Registration (the
"Participating Holders") a certificate signed by the Chairman or President of
the Company stating that in the good faith judgment of the Board of Directors of
the Company, that such Demand Registration would materially and adversely affect
any proposed or pending material acquisition, merger, business combination or
other material transaction involving the Company and that such disclosure is not
in the best interests of the Company and its shareholders, the Company shall
have the right (i) to postpone (or, if necessary or advisable, withdraw) the
filing, or delay the effectiveness, of a registration statement, (ii) to fail to
keep such registration statement Continuously Effective and (iii) not to amend
or supplement the registration statement or included prospectus after the
effectiveness of the registration statement; provided that no one such
postponement shall exceed 90 days in any six-month period and all such
postponements shall not exceed 120 days in the aggregate in any 12-month period.
The Company shall advise the Covered Holders of any such determination as
promptly as practicable. Upon written notice from the Company to the
Participating Holders delivered within 30 days of a demand to register
Registrable Securities under this Section 7.6(a), the Covered Holders' right to
demand registration pursuant to this Section 7.6(a) shall be suspended during
the period commencing 7 days prior to and ending 90 days following the effective
date of a registration statement for an underwritten public offering of the
Common Stock.

                       (ii)  All Participating Holders proposing to distribute
securities through such registration shall enter into an underwriting agreement
with the managing or lead managing underwriter in the form customarily used by
such underwriter with such changes thereto as the parties thereto shall agree.
If any Participating Holder disapproves of the terms of any such underwriting,
it may elect to withdraw therefrom by written notice to the Company and the
managing or lead managing underwriter. Any Registrable Securities so withdrawn
from such underwriting shall be withdrawn from such registration.

                       (iii) Whenever a registration is demanded pursuant to
this Section 7.6(a), unless a managing or lead managing underwriter objects
thereto, the Company may include in such registration securities for offering by
the Company and any other holder of securities, it being understood, however,
that the Company's and such other holder's right of inclusion in such
registration shall be subordinate to, and not pari passu with, the rights of the
Participating Holders.

                       (iv)  If the managing underwriter thereof determines that
the total number of shares of Registrable Securities to be sold in such offering
shall be limited due to market conditions or otherwise, the reduction in the
total number of shares offered shall be made in accordance with Section
7.6(b)(ii).

                       (v)   The Participating Holders shall have the right to
select the underwriter or underwriters and manager or managers to administer
such offering; provided, however, that each Person so selected shall be
acceptable to the Company in its reasonable judgment.

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                                                               Execution Version

                       (vi)   The Company shall be obligated to effect not more
than two Demand Registrations; provided, however, that the Covered Holders may
make unlimited Demand Registration requests in accordance with Subsection (i) so
long as the Company is S-3 Eligible. For purposes of the preceding sentence, a
Demand Registration shall not be deemed to have been effected (i) unless a
Demand Registration Statement with respect thereto has become effective, (ii) if
after such Demand Registration Statement has become effective, such Demand
Registration Statement or the related offer, sale or distribution of Registrable
Securities thereunder is interfered with by any stop order, injunction or other
order or requirement of the SEC or other governmental agency or court for any
reason not attributable to the Participating Holders and such interference is
not thereafter eliminated, (iii) if the conditions to closing specified in the
underwriting agreement entered into in connection with such registration are not
satisfied or waived, other than by reason of a failure on the part of the
Participating Holders, (iv) upon the Company availing itself of Subsection (i)
above or (v) the number of shares of Registrable Securities to be sold by the
Covered Holders requesting a Demand Registration were reduced pursuant to
Subsection (iv) above. If the Company shall have complied with its obligations
under this Agreement, a right to demand a registration pursuant hereto shall be
deemed to have been satisfied upon the earlier of (x) the date as of which all
of the Registrable Securities included therein shall have been distributed
pursuant to the Demand Registration Statement, and (y) the date as of which such
Demand Registration shall have been Continuously Effective for a 90-day period
or other period specified herein (not to exceed 120 days) following the
effectiveness of such Demand Registration Statement, provided no stop order or
similar order, or proceedings for such an order, is thereafter entered or
initiated.

                       (vii)  The Company shall use the Company's commercially
reasonable efforts to keep the relevant registration statement Continuously
Effective, if a Demand Registration Statement, for up to 90 days or until such
earlier date as of which all the Registrable Securities under the Demand
Registration Statement shall have been disposed of in the manner described in
the Registration Statement, or such longer period (but in no event longer than
120 days) as in the judgment of counsel for the underwriters a prospectus is
required by law to be delivered in connection with sales of Registrable
Securities by an underwriter or dealer in accordance with plan of distribution
included in such Demand Registration Statement. Notwithstanding the foregoing,
if for any reason the effectiveness of a Demand Registration Statement pursuant
to this Subsection is delayed or suspended or filing of the Demand Registration
Statement or seeking effectiveness thereof is postponed as permitted herein, the
commencement of the foregoing period shall be extended by the aggregate number
of days of such suspension or postponement.

                       (viii) Except for registration statements on Forms S-4,
S-8 or any successor thereto, the Company will not file with the SEC any other
registration statement with respect to its capital stock, whether for its own
account or that of other stockholders, from the date of receipt of a notice from
requesting holders pursuant to this Section 7.6 until the completion of the
period of distribution of the registration contemplated thereby.

                 (b)   Piggy-back Registration.

                       (i)    If at any time the Company intends to file on its
behalf or on behalf of any of its shareholders (including Covered Holders, with
respect to Registrable Securities, and

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                                                               Execution Version

eligible holders of Series B Registrable Securities) a registration statement in
connection with a public offering of any securities of the Company on a form and
in a manner that would permit the registration for offer and sale under the
Securities Act of Registrable Securities held by a Covered Holder, other than a
registration statement on Form S-8 or Form S-4 or any successor form or other
forms promulgated for similar purposes, then the Company shall give written
notice (an "Intended Offering Notice") of such intention to each Covered Holder
at least 30 business days prior to the anticipated filing date of such
registration statement. Such Intended Offering Notice shall offer to include in
such registration statement for offer to the public such number or amount of
Registrable Securities as each such Covered Holder may request, subject to the
conditions set forth herein, and shall specify, to the extent then known, the
number and class of securities proposed to be registered, the proposed date of
filing of such registration statement, any proposed means of distribution of
such securities, any proposed managing underwriter or underwriters of such
securities and (if available or as soon as available) a good faith estimate
(which may be a range) by the Company of the proposed maximum offering price of
such securities, as such price is proposed to appear on the facing page of such
registration statement. Any Covered Holder desiring to have Registrable
Securities included in such registration statement and offered to the public
shall so advise the Company in writing (the written notice of any such Covered
Holder being a "Piggy-back Notice") not later than 10 business days after the
Company's delivery to the Covered Holders of the Intended Offering Notice,
setting forth the number of Registrable Securities such Covered Holder desires
to have included in the registration statement and offered to the public. Upon
the request of the Company, such Covered Holders shall enter into such
underwriting, custody and other agreements as shall be customary in connection
with registered secondary offerings or necessary or appropriate in connection
with the offering.

                       (ii)  In connection with an underwritten offering, if the
managing underwriter or underwriters advise the Company in writing that in its
or their opinion the number of securities proposed to be registered exceeds the
number that can be sold in such offering, the Company shall include in such
registration the number of securities that, in the opinion of such managing
underwriter or underwriters, can be sold as follows: (i) first, the securities
that the Company proposes to sell on its behalf or, if the offering is a Demand
Registration the securities proposed to be sold, for the shareholder or
shareholders initiating such Demand Registration, as the case may be, (ii)
second, holders of Registrable Securities and holders of Series B Registrable
Securities, pro rata among such holders and (iii) third, other securities
requested to be included in such registration; provided, however, the Covered
Holders and the eligible holders of Series B Registrable Securities desiring to
have securities included in such an underwritten offering (other than in the
case of a Demand Registration) shall not be reduced to less than 20 percent of
the aggregate securities to be sold in such offering, split in equal one-half
parts (10 percent each) between the Covered Holders and the holders of the
Series B Registrable Securities. Notwithstanding the provisions of this
Subsection (ii), if the registration was initiated at the request of the holders
of Series B Registrable Securities pursuant to their demand rights as set forth
in the Series B Registration Rights Agreement, priority in underwriter cutbacks
with respect to such registration shall be governed by the provisions of the
Series B Registration Rights Agreement, provided that the Covered Holders that
have requested inclusion of their securities to be included therein shall have
priority over any persons, other than Covered Holders as defined in the Series B
Registration Rights Agreement, holding securities requested to be included in
such registration, and the twenty percent requirement set forth in the previous

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                                                               Execution Version

sentence shall not apply to any such registration initiated at the request of
holders of Series B Registrable Securities.

                       (iii) The rights of the Covered Holders pursuant to
Subsections (a) and (b) hereof are cumulative, and the exercise of rights under
one such Subsection shall not exclude the subsequent exercise of rights under
the other such Subsection. Notwithstanding anything herein to the contrary, the
Company may abandon and/or withdraw any registration (other than pursuant to
Subsection (a) hereof) as to which any right under this Subsection (b) may exist
at any time and for any reason without liability hereunder. In such event, the
Company shall so notify each Covered Holder that has delivered a Piggy-back
Notice to participate therein.

                       (iv)  Except for registration rights granted by the
Company after the date hereof which are subordinate to the rights of the Covered
Holders pursuant to Subsection (a) hereof and this Subsection (b), prior to the
termination of this Agreement, the Company shall not grant any registration
rights to any other Person without the consent of holders of a majority of the
Registrable Securities then outstanding.

                 (c)   Registration Statement Information Relating to the
Covered Holders. Each Covered Holder shall promptly upon receipt of written
request provide the Company or any underwriter or counsel participating or
otherwise involved in any such registration with any information relating to the
Covered Holder or the Registrable Securities that is reasonably required to be
included in the registration statement or the prospectus, or any amendment
thereof, relating to such offering or required to cause the registration to be
declared and remain effective. Such information shall be submitted in writing,
signed by the Covered Holder, or a duly authorized representative or agent
thereof, and shall state that the information is submitted specifically for the
purpose of inclusion in the registration statement, prospectus, offering
circular or other document related to the registration or qualification of the
Registrable Securities pursuant hereto. If the Covered Holder fails within a
reasonable time to provide such information, the Company may exclude from such
registration the Registrable Securities requested by the Covered Holder to be
included therein.

                 (d)   Registration Procedures. If and whenever the Company is
required to effect the registration of any Registrable Securities of a Covered
Holder pursuant hereto, the Company will:

                       (i)   prepare and file with the SEC a registration
statement with respect to such Registrable Securities and use reasonable efforts
to cause such registration statement to become and remain effective as provided
herein; provided, however, that before filing a registration statement or
prospectus or any amendments or supplements thereto, including documents
incorporated by reference after the initial filing of the registration statement
and prior to effectiveness thereof, the Company shall furnish to counsel for
each Covered Holder participating in the registration and underwriters, copies
of all such documents in the form substantially as proposed to be filed with the
SEC at a reasonable time prior to filing for review and comment by such counsel;

                       (ii)  prepare and file with the SEC such amendments and
supplements to such registration statement and the prospectus used in connection
with such registration

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                                                               Execution Version

statement as may be necessary to comply with the provisions of the Securities
Act and rules thereunder with respect to the distribution of all securities
covered by such registration statement and as may be reasonably requested by a
Covered Holder participating in the registration or necessary to keep such
registration statement effective. If the registration is for an underwritten
offering, the Company shall amend the registration statement or supplement the
prospectus whenever required by the terms of the underwriting agreement. Pending
such amendment or supplement each Covered Holder participating in the
registration, upon written notice by the Company, shall cease making offers or
Transfers of Registrable Securities pursuant to the prior prospectus. In the
event that any Registrable Securities included in a registration statement
subject to, or required by, this Agreement remain unsold at the end of the
period during which the Company is obligated to use its commercially reasonable
efforts to maintain the effectiveness of such registration statement, the
Company may file a post-effective amendment to the registration statement for
the purpose of removing such securities from registered status;

                       (iii) notify each Covered Holder participating in the
registration and the Underwriters' Representative and (if requested) confirm
such advise in writing, as soon as practicable after notice thereof is received
by the Company (i) when a registration statement or any amendment thereto has
been filed or becomes effective, the prospectus or any amendment or supplement
to the prospectus included therein has been filed, and, to furnish each Covered
Holder participating in the registration and the underwriters with copies
thereof, (ii) of any request by the SEC for amendments or supplements to the
registration statement or the prospectus included therein or for additional
information, (iii) if at any time the representations and warranties of the
Company cease to be true and correct, and (iv) of the receipt by the Company of
any notification with respect to the suspension or qualification of the
Registrable Securities for offering or sale in any jurisdiction or the
initiation or threatening of any proceeding for such purpose;

                       (iv)  immediately notify each Covered Holder
participating in the registration, at any time when a prospectus relating
thereto is required to be delivered under the Securities Act, of the happening
of any event as a result of which the prospectus included in the registration
statement, as then in effect, includes an untrue statement of a material fact or
omits to state any material fact required to be stated therein or necessary to
make the statements therein not misleading in the light of the circumstances
then existing, and if it is necessary, in the opinion of counsel to the Company,
to prepare and file with the SEC such amendments and supplements to such
registration statement and the prospectus used in connection therewith as may be
necessary to keep such registration statement effective and current and to
comply with the provisions of the Securities Act with respect to the sale or
other disposition of all shares covered by such registration statement,
including such amendments and supplements as may be necessary to reflect the
intended method of disposition from time to time of each Covered Holder
participating in the registration if the registration is effected in connection
with an offering which is not underwritten;

                       (v)   cooperate with each Covered Holder participating in
the registration and the Underwriters' Representatives to facilitate the timely
preparation and delivery of certificates representing Registrable Securities to
be sold and not bearing any restrictive legends; and enable such Registrable
Securities to be in such denomination and

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                                                               Executive Version

registered in such names as the Underwriters' Representative may request at
least two business days prior to the sale of Registrable Securities to the
underwriters;

                       (vi)   cooperate with each Covered Holder participating
in the registration in connection with any filings required to be made with the
NASD, and otherwise use its best efforts to comply with the rules, by-laws and
regulations of the NASD as they apply to the registration;

                       (vii)  furnish to each Covered Holder participating in
the registration such number of copies of a prospectus, including a preliminary
prospectus and any amendments and any supplements thereto, in conformity with
the requirements of the Securities Act, as each Covered Holder participating in
the registration may reasonably request in order to facilitate the public sale
or other disposition of the Registrable Securities owned by such Covered Holder;

                       (viii) use reasonable efforts to register or qualify the
Registrable Securities covered by such registration statement under such other
securities or blue sky or other applicable laws of such jurisdictions within the
United States as each Covered Holder participating in the registration shall
reasonably request to enable such Covered Holder to consummate the public sale
or other disposition of the Registrable Securities owned by the Covered Holder,
and to obtain the withdrawal of any order suspending the effectiveness of a
registration statement, or the lifting of any suspension of the qualification
(or exemption from qualification) of the offer and Transfer of any of the
Registrable Securities in any jurisdiction, at the earliest possible moment;
except that the Company shall not for any such purpose be required (i) to
qualify generally to do business as a foreign corporation in any jurisdiction in
which it would not be required to so qualify but for such registration or
qualification, (ii) to subject itself to taxation in any such jurisdiction, or
(iii) to consent to general service of process in any such jurisdiction;

                       (ix)   use its best efforts to furnish to each Covered
Holder who has included Registrable Securities in the registration statement a
signed counterpart, addressed to the Covered Holder, of (A) an opinion of
counsel for the Company, dated the date of the closing under the underwriting
agreement, and (B) a "cold comfort" letter signed by the independent public
accountants who have issued a report on the Company's financial statements
included in such registration statement dated the date of effectiveness of the
registration statement and the date of the closing under the underwriting
agreement, covering substantially the same matters with respect to such
registration statement (and the prospectus included therein) and, in the case of
such accountants' letters, with respect to events subsequent to the date of such
financial statements, as are customarily covered in opinions of issuer's counsel
and in accountants' letters delivered to underwriters in underwritten public
offerings of securities and, in the case of the accountants' letters, such other
financial matters as such Covered Holder may reasonably request;

                       (x)    otherwise use its best efforts to comply with all
applicable rules and regulations of the SEC, and make available to its security
holders, as soon as reasonably practicable, an earnings statement covering the
period of at least 12 months, beginning with the first month of the first fiscal
quarter after the effective date of such registration statement, which earnings
statement shall satisfy the provisions of Section 11(a) of the Securities Act;

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                                                               Execution Version

                       (xi)   use its best efforts to list such Registrable
Securities on each securities exchange or over-the-counter market on which
shares of Common Stock are then listed, if such Registrable Securities are not
already so listed and if such listing is then permitted under the rules of such
exchange and, if shares of Common Stock are not then listed on a securities
exchange or over-the-counter market, to use its best efforts to cause such
Registrable Securities to be listed on such securities exchange or
over-the-counter market as the managing or lead managing underwriter shall
reasonably request;

                       (xii)  use its best efforts to provide a transfer agent
and registrar for such Registrable Securities not later than the effective date
of such registration statement;

                       (xiii) if requested by the managing or lead managing
underwriter for any underwritten offering that includes any Registrable
Securities, enter into an underwriting agreement with the underwriters of such
offering, such agreement to contain such representations and warranties by the
Company and such other terms and conditions as are contained in underwriting
agreements customarily used by such managing or lead managing underwriter with
such changes as the parties thereto shall agree, including, without limitation,
provisions relating to indemnification and contribution in lieu thereof;

                       (xiv)  cooperate with each Covered Holder participating
in the registration, and the Underwriters' Representative for such offering in
the marketing, and customary selling efforts relating to the Registrable
Securities, including participating for a period not in excess of five (5)
business days per Demand Registration in customary "road show" presentations as
may be reasonably requested by the Underwriters' Representative;

                       (xv)   promptly notify each Covered Holder participating
in the registration of any stop order issued or threatened to be issued by the
SEC in connection therewith and take all reasonable actions required to prevent
the entry of such stop order or to remove it if entered; and

                       (xvi)  make available for inspection by each Covered
Holder participating in the registration, any underwriter participating in such
offering and the representatives of such Covered Holder and such underwriter all
financial and other information as shall be reasonably requested by them, and
provide the Covered Holder, any underwriter participating in such offering and
the representatives of the Covered Holder and such underwriter the reasonable
opportunity to discuss the business affairs of the Company with its principal
executives and independent public accountants who have certified the audited
financial statements included in such registration statement, in each case all
as necessary to enable them to exercise their due diligence responsibilities
under the Securities Act; provided, however, that information that the Company
determines, in its reasonable and good faith judgment, to be confidential and
which the Company advises such Person in writing, is confidential shall not be
disclosed unless such Person signs a confidentiality agreement reasonably
satisfactory to the Company.

                 (e)   Termination of Sales. During the effective period of any
registration statement covering Registrable Securities, each Covered Holder will
not effect sales thereof after receipt of telegraphic or written notice from the
Company to suspend sales to permit the

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Company to correct or update a registration statement or prospectus until such
Covered Holder receives written notice from the Company that the registration
statement or prospectus has been corrected or updated. At the end of the
effective period of any registration statement covering any Registrable
Securities, each Covered Holder participating in the registration shall
discontinue sales of shares pursuant to such registration statement upon receipt
of notice from the Company of its intention to remove from registration the
shares covered by such registration statement which remain unsold, and such
Covered Holder shall notify the Company of the number of shares registered which
remain unsold immediately upon receipt of such notice from the Company.

                 (f)   Expenses of Registration. With respect to the
registrations effected pursuant to Subsections (a) and (b) hereof, the Company
shall bear and pay all expenses incurred in connection with any registration,
filing, or qualification of Registrable Securities with respect to such
registrations, including all registration, filing and NASD fees, all fees and
expenses of complying with securities or blue sky laws, all word processing,
duplicating and printing expenses, messenger and delivery expenses, the
reasonable fees and disbursements of counsel for the Company, and of the
Company's independent public accountants, including the expenses of any special
audits or "cold comfort" letters required by or incident to such performance and
compliance, premiums and other costs of policies of insurance obtained by the
Company against liabilities arising out of the public offering of Registrable
Securities being registered and the reasonable fees and disbursements of one
counsel designated by the majority of Covered Holders participating in the
registration (the "Registration Expenses"), but in no event shall the Company
bear underwriting discounts and commissions and transfer taxes relating to
Registrable Securities or fees and expenses of more than one counsel to the
Covered Holders participating in the registration and provided that the Company
shall not be required to pay for any expenses of any registration begun pursuant
to Subsection (a) if the registration is subsequently withdrawn at the request
of the Covered Holders making the demand (in which case the Covered Holders
shall bear such expense), other than by reason of failure of the Company to
comply with its covenants contained herein unless the Covered Holders making the
demand agrees that such withdrawn registration shall constitute one of the
Demand Registrations under Subsection (a) hereof.

                 (g)   Indemnification.

                       (i)   In any registration in which a Covered Holder
participates, the Company will indemnify such Covered Holder and each
underwriter and selling broker for each Covered Holder and each officer and
director of each Covered Holder and each person, if any, who controls such
Covered Holder or any such underwriter or broker within the meaning of Section
15 of the Securities Act, against all claims, losses, damages, expenses and
liabilities (or actions in respect thereof), including any of the foregoing
incurred in settlement of any litigation, commenced or threatened, arising out
of or based on any untrue statement (or alleged untrue statement) of a material
fact contained in any preliminary prospectus or amended preliminary prospectus
or in the prospectus, offering circular or other document incident to any
registration, qualification or compliance (or in any related registration
statement, notification or the like) as such may be amended or supplemented from
time to time or any omission (or alleged omission) to state therein a material
fact required to be stated therein or necessary to make the statements therein,
in light of the circumstances under which they were made, not misleading, or any
violation by the Company of the Securities Act or any rule or regulation
promulgated thereunder

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or any state securities laws or regulations applicable to the Company in
connection with any such registration, qualification or compliance, and will
reimburse each Covered Holder and each such underwriter, broker and controlling
person for any legal and any other expenses reasonably incurred, as such
expenses are incurred, in connection with investigating or defending any such
claim, loss, damage, liability or action; provided, however, that the Company
will not be liable in any such case to the extent that any such claim, loss,
damage or liability arises out of or is based on any untrue statement or
omission made in reliance upon and in conformity with written information
furnished to the Company in an instrument executed by a Covered Holder or the
underwriter for a Covered Holder or any representative of a Covered Holder or
the underwriter for a Covered Holder and stated to be specifically for use
therein.

                       (ii)  In any registration in which a Covered Holder
participates, such Covered Holder will indemnify the Company and its officers
and directors, each person, if any, who controls any thereof within the meaning
of Section 15 of the Securities Act and their respective successors and any
underwriter for the Company for such registration and each other security holder
participating in the registration against all claims, losses, damages, expenses
and liabilities (or actions in respect thereof) arising out of or based on any
untrue statement (or alleged untrue statement) of a material fact contained in
any preliminary prospectus or amended prospectus or in the prospectus, offering
circular or other document incident to any registration statement, qualification
or compliance (or in any related registration statement, notification or the
like) as such may be amended or supplemented from time to time or any omission
(or alleged omission) to state therein a material fact required to be stated
therein or necessary to make the statements therein, in light of the
circumstances under which they were made, not misleading, and will reimburse the
Company and each other person indemnified pursuant to this paragraph (ii) for
any legal and any other expenses reasonably incurred, as such expenses are
incurred, in connection with investigating or defending any such claim, loss,
damage, liability or action; provided, however, that this paragraph (ii) shall
apply only if (and only to the extent that) such statement or omission was made
in reliance upon and in conformity with written information (including, without
limitation, written negative responses to inquiries) furnished to the Company
specifically for inclusion in the prospectus, offering circular, or other
document incident to the registration statement by an instrument duly executed
by the Covered Holder or its representatives, and as to which the Company had no
actual knowledge. Notwithstanding the foregoing, the liability of a Covered
Holder under this Subsection (ii) shall be limited to an amount equal to the
aggregate proceeds received by the Covered Holder from the sale of its shares in
such registration, unless such liability arises out of or is based on willful
misconduct by the Covered Holder.

                       (iii) Each party entitled to indemnification hereunder
(the "Indemnified Party") shall give notice to the party required to provide
indemnification (the "Indemnifying Party") promptly after such Indemnified Party
has actual knowledge of any claim as to which indemnity may be sought, and shall
permit the Indemnifying Party (at its expense) to assume the defense of any
claim or any litigation resulting therefrom, provided that counsel for the
Indemnifying Party, who shall conduct the defense of such claim or litigation,
shall be satisfactory to the Indemnified Party, and the Indemnified Party may
participate in such defense at such party's expense, and provided, further, that
the omission by any Indemnified Party to give notice as provided herein shall
not relieve the Indemnifying Party of its obligations under this Section 7.6(g)
except to the extent that the omission results from a failure of actual notice
to the

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Indemnifying Party by the Indemnified Party and such Indemnifying Party is
damaged solely as a result of the failure to give notice; and provided further,
however, that the Indemnifying Party shall not be entitled to assume the defense
for matters as to which there is, in the opinion of counsel to the Indemnified
Party, a conflict of interest or separate and different defenses. No
Indemnifying Party, in the defense of any such claim or litigation, shall,
except with the consent of each Indemnified Party, consent to entry of any
judgment or enter into any settlement which does not include as an unconditional
term thereof the giving by the claimant or plaintiff to such Indemnified Party
of a release from all liability in respect of such claim or litigation.

                       (iv)  The payments with respect to any indemnity required
by this Section 7.6(g) shall be made by periodic payments during the course of
the investigation or defense, as and when bills are received or expenses
incurred, upon submission of supporting invoices or other claims for payment,
including any calculations necessary to pro-rate any amounts payable pursuant to
the indemnity.

                 (h)   Contribution.

                       (i)   If the indemnification provided for in Section
7.6(g) hereof is unavailable to the Indemnified Parties in respect of any
losses, claims, damages, liabilities or expenses (or actions in respect thereof)
referred to therein, then each such Indemnifying Party, in lieu of indemnifying
such Indemnified Party, shall contribute to the amount paid or payable by such
Indemnified Party as a result of such losses, claims, damages, liabilities or
expenses (or actions in respect thereof) in such proportion as is appropriate to
reflect the relative fault of the Indemnifying Party on the one hand and the
Indemnified Party on the other in connection with the statement or omission
which resulted in such losses, claims, damages, liabilities or expenses (or
actions in respect thereof), as well as any other relevant equitable
considerations. The relative fault shall be determined by reference to, among
other things, whether the untrue statement (or alleged untrue statement) of a
material fact or the omission (or alleged omission) to state a material fact
relates to information supplied by the Indemnifying Party or the Indemnified
Party and the parties' relative intent, knowledge, access to information and
opportunity to correct or prevent such statement or omission. The Company and
each Covered Holder agree that it would not be just and equitable if
contribution pursuant to this Section 7.6(h) were determined by pro rata
allocation or by any other method of allocation which does not take account of
the equitable considerations referred to above. The amount paid or payable by an
Indemnified Party as a result of the losses, claims, damages, liabilities or
expenses (or actions in respect thereof) referred to above in this Section
7.6(h) or in Section 7.6(g) shall be deemed to include any legal or other
expenses reasonably incurred by such Indemnified Party in connection with
investigating or defending any such action or claim.

                       (ii)  Notwithstanding anything to the contrary contained
herein, the obligation of a Covered Holder to contribute pursuant to this
Section 7.6(h) is several and not joint and a Covered Holder shall not be
required to contribute any amount in excess of the amount by which the total
price at which the shares of the Covered Holder were offered to the public
exceeds the amount of any damages which the Covered Holder has otherwise been
required to pay by reason of such untrue statement (or alleged untrue statement)
or omission (or alleged omission).

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                       (iii) No person guilty of fraudulent misrepresentation
(within the meaning of Section 11 (f) of the Securities Act) shall be entitled
to contribution from any person who was not guilty of such fraudulent
misrepresentation.

                 (i)   Rule 144 Requirements. The Company shall make whatever
filings with the SEC or otherwise and undertake to make publicly available and
available to each Covered Holder, pursuant to Rule 144 of the SEC under the
Securities Act (or any successor rule or regulation), such information as is
necessary to enable a Covered Holder to make sales of Registrable Securities
pursuant to that Rule. The Company shall furnish to a Covered Holder, upon
request, a written statement executed by the Company as to the steps it has
taken to comply with the current public information requirements of Rule 144.

                 (j)   Survival and Termination of Rights. The agreements and
covenants contained in this Section 7.6 shall be continuing and shall survive
any Transfer of the Shares to any Person who is a Covered Holder. However, the
rights of Covered Holders to cause the Company to register their Registrable
Securities hereunder shall terminate with respect to such securities and such
securities shall no longer be deemed to be Registrable Securities following a
bona fide, firmly underwritten public offering of such Registrable Securities
under the Securities Act resulting in less than 20% of the Registrable
Securities remaining outstanding or at such time as the Covered Holders are able
to dispose of all of their Registrable Securities in one three-month period
pursuant to the provisions of Rule 144.

                 (k)   Sales During Registration. If so requested by the
Underwriters' Representative in connection with an offering of any Registrable
Securities, the Company shall agree not to effect any sale or distribution of
shares of Common Stock during the 7-day period prior to, and during the 90-day
period beginning on, the date a registration statement is declared effective
under the Securities Act by the SEC. The Company agrees to use its commercially
reasonable efforts to obtain from each holder of restricted securities of the
Company the same as or similar to those being registered by the Company on
behalf of each Covered Holder, or any restricted securities convertible into or
exchangeable or exercisable for any of its securities, an agreement not to
effect any sale or distribution of such securities (other than securities
purchased in a public offering) during any period referred to in this paragraph,
except as part of any such registration statement if permitted. Without limiting
the foregoing, if the Company grants any Person (other than a holder of
Registrable Securities) any rights to demand or participate in a registration,
the Company agrees that the agreement with respect thereto shall include such
Person's agreement as contemplated by the previous sentence.

         1.2     Section 7.9 of the Common Stock Purchase Agreement is hereby
amended and restated in its entirety to read as follows:

                 7.9   Preemptive Rights. The Company shall, prior to any
         issuance by the Company of any of its securities (other than debt
         securities with no equity feature), offer to each Covered Holder by
         written notice the right, for a period of thirty (30) days, to purchase
         the Covered Holder's Pro Rata Share (as such term is defined below) of
         such securities for cash at a price equal to the price or other
         consideration for which such securities are to be issued; provided,
         however, that the preemptive rights of each Covered Holder pursuant to
         this Section 7.9 shall not apply to securities issued (A) upon

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                                                               Execution Version

         conversion of any shares of the Preferred Stock outstanding on the
         Closing Date (B) as a stock dividend or upon any subdivision of shares
         of Common Stock, provided that the securities issued pursuant to such
         stock dividend or subdivision are limited to additional shares of
         Common Stock, (C) pursuant to options or other rights which are issued
         pursuant to the 1994 or 1995 Stock Option Plans or any similar plan
         approved by the Board of Directors of the Company and the holders of
         Voting Securities within one year of such Board approval or (D) in
         payment of dividend obligations on the Preferred Stock. The Company's
         written notice to each Covered Holder shall describe the securities
         proposed to be issued by the Company and specify the number, price and
         payment terms. A Covered Holder may accept the Company's offer as to
         the full number of securities offered to it or any lesser number by
         written notice thereof given by it to the Company prior to the
         expiration of the aforesaid thirty (30) day period, in which event the
         Company shall promptly sell and such Covered Holder shall buy, upon the
         terms specified, the number of securities agreed to be purchased by the
         Covered Holder. For purposes of this Section 7.9, a Covered Holder's
         "Pro Rata Share" of offered securities shall be determined by
         multiplying the full number of securities offered by the Company by a
         fraction, the numerator of which shall be the number of shares of
         Common Stock held by the Covered Holder as of the date of the Company's
         notice of offer and the denominator of which shall be the aggregate
         number of shares of Common Stock (calculated as aforesaid) held on such
         date by all holders of capital stock of the Company. The Company shall
         be free at any time following expiration of the thirty-day offer period
         and prior to ninety (90) days after the expiration of the thirty day
         offer period, to offer and sell to any third party or parties the
         number of the securities not agreed by the Covered Holders to be
         purchased by them, all at a price and on payment terms no less
         favorable to the Company than those specified in such notice of offer
         to the Covered Holders. However, if such third party sale or sales are
         not consummated within such ninety (90) day period, the Company shall
         not sell such securities as shall not have been purchased within such
         period without again complying with this Section 7.9.

         1.3     Section 8.6(b) of the Common Stock Purchase Agreement is hereby
amended and restated in its entirety to read as follows:

         8.6     Restrictions on Transfer of Voting Securities.

                 (a)   The Purchaser shall not, directly or indirectly, sell or
Transfer any Voting Securities for a period of one year commencing with the
Closing Date.

                 (b)   Subject to Section 8.6(a), the Purchaser shall not,
directly or indirectly, sell or Transfer any Voting Securities, except

                       (i)   to the Company or any person or group approved by
the Company;

                       (ii)  to an Affiliate of the Purchaser, as long as such
Affiliate agrees to hold such Voting Securities subject to all the provisions of
this Agreement, including this Section 8.6;

                       (iii) pursuant to Rule 144 under the Securities Act;

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                                                               Execution Version

                       (iv)  pursuant to an effective registration statement
under the Securities Act;

                       (v)   subject to the Company's right of first refusal as
set forth in Section 9.1 hereof, in transactions not otherwise described in this
Section 8.6(b);

                       (vi)  pursuant to a bona fide pledge of such Voting
Securities to an institutional lender to secure a loan, guarantee or other
financial support, provided that such lender agrees to hold such Voting
Securities subject to all provisions of this Agreement and any sale or
disposition by such lender of such pledged Voting Securities shall be subject to
the limitations of this Section 8.6; or

                       (vii) pursuant to a pro rata dividend to the stockholders
of the Purchaser.

         1.4     Section 10 of the Common Stock Purchase Agreement is hereby
amended to delete the defined term "Inclusion Notice" therefrom and to add
thereto in the appropriate alphabetical position the following new definitions:

         "Covered Holder" means (i) any member of the Purchaser Group and (ii)
         any other Person that holds a minimum of 20 percent of the Registrable
         Securities.

         "Demand Registration Statement" shall have the meaning set forth in
         Section 7.6(a).

         "Intended Offering Notice" shall have the meaning set forth in Section
         7.6(b).

         "Piggy-back Notice" shall have the meaning set forth in Section 7.6(b).

         "S-3 Eligible" means that the Company meets the registrant requirements
         and transaction requirements for the use of Form S-3 (or any successor
         form thereto) of the SEC, as set forth in the General Instructions to
         such Form (or any successor form thereto).

         "Series B Registrable Securities" means any securities of the Company
         that may be "Registrable Securities" under the Series B Registration
         Rights Agreement.

         "Series B Registration Rights Agreement" means that certain
         Registration Rights Agreement dated as of April 29, 2003 by and among
         the Company and the shareholders listed on Exhibit A thereto.

         1.5     The second sentence of Section 11.5 of the Common Stock
Purchase Agreement is hereby amended in its entirety to read as follows:

         Except as otherwise provided in this Agreement, this Agreement may not
         be assigned by a party without the prior written consent of the other
         party except by operation of law and except, in the case of the
         Purchaser, to an Affiliate of the Purchaser or as otherwise provided in
         Section 8.6(b), in which case the assignee shall be subject to all of
         the provisions of this Agreement except as otherwise provided herein.

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                                                               Executive Version

     Section 2.  Definitions. All capitalized terms used herein and not
otherwise defined herein shall have the meanings ascribed thereto in the Common
Stock Purchase Agreement.

     Section 3.  Governing Law. This Amendment shall be governed in all respects
by the laws of the State of North Carolina as applied to contracts entered into
solely between residents of, and to be performed entirely within, such state.

     Section 4.  Entire Agreement. This Amendment, the Common Stock Purchase
Agreement, that certain letter agreement between the Company and the Purchaser
dated January 15, 2003 (the "Letter Agreement") and the other documents
delivered pursuant hereto constitute the full and entire understanding and
agreement between the parties with regard to the subject matter hereof and
thereof and supersede all prior agreements and understandings among the parties
relating to the subject matter hereof and in the Common Stock Purchase Agreement
and the Letter Agreement. No party shall be liable or bound to any other party
in any manner by any warranties, representations or covenants except as
specifically set forth herein or in the Common Stock Purchase Agreement or
Letter Agreement. This Amendment, the Common Stock Purchase Agreement, the
Letter Agreement or any term hereof or thereof may be amended, waived,
discharged or terminated other than by a written instrument signed by the party
against whom enforcement of any such amendment, waiver, discharge or termination
is sought.

     Section 5.  Counterparts. This Amendment may be executed in any number of
counterparts, each of which may be executed by fewer than all of the parties,
each of which shall be enforceable against the parties actually executing such
counterparts, and all of which together shall constitute one instrument.

     Section 6.  Severability. In the event that any provision of this Amendment
becomes or is declared by a court of competent jurisdiction to be illegal,
unenforceable or void, this Amendment shall continue in full force and effect
without said provision; provided, that no such severability shall be effective
if it materially changes the economic impact of this Amendment on any party.

     Section 7.  Headings. Headings of the various sections of this Amendment
have been inserted for convenience of reference only and shall not be relied
upon in construing this Amendment. Use of any gender herein to refer to any
person shall be deemed to comprehend masculine, feminine and neuter unless the
context clearly requires otherwise.

     Section 8.  Expenses. Each party hereto shall pay its own costs and
expenses incurred in connection herewith, including the fees of its counsel,
auditors and other representatives, whether or not the transactions contemplated
herein are consummated.

     Section 9.  Third Party Beneficiaries. Nothing in this Amendment shall
create or be deemed to create any rights in any person or entity not a party to
this Amendment except for such rights as may exist by virtue of any contract or
other agreement existing on the date hereof.

     Section 10. Attorneys' Fees. The prevailing party in any litigation between
any Covered Holder and the Company involving this Amendment shall be entitled to
recover from the other party its reasonable attorneys' fees and costs.

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                                                               Executive Version

     Section 11. Conflicts. To the extent any provision of this Amendment
conflicts with any provision of the Series B Registration Rights Agreement, the
provision contained in this Amendment shall govern.

     Section 12. Amendment. Sections 7.6, 7.9 and 8.6(b) of that certain Stock
Purchase Agreement dated August 28, 1998 (the "1998 Purchase Agreement") between
Cardiovascular Diagnostics, Inc. (predecessor to the Company) and Chiron
Diagnostics Corporation (predecessor to the Purchaser), as amended by Section
11.18 of the Common Stock Purchase Agreement, are hereby amended and restated in
their entirety in Sections 7.6, 7.9 and 8.6(b), respectively, of the Common
Stock Purchase Agreement as amended and restated in this Amendment. Sections 10
and 11.5 of the 1998 Purchase Agreement are hereby amended in Sections 10 and
11.5, respectively, of the Common Stock Purchase Agreement as amended by this
Amendment.

                     [The next page is the signature page.]

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IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be executed
by their respective authorized officers as of the date first above written.

                                         PHARMANETICS, INC.



                                         By: ___________________________________
                                             Name:
                                             Title:


                                         BAYER CORPORATION



                                         By: ___________________________________
                                             Name:
                                             Title: