<PAGE>
                                                                 EXHIBIT 10.19


         THIS WARRANT HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933,
AS AMENDED. NO SALE OR DISPOSITION MAY BE EFFECTED EXCEPT IN COMPLIANCE WITH
RULE 144 UNDER SAID ACT OR WITHOUT AN EFFECTIVE REGISTRATION STATEMENT RELATED
THERETO OR AN OPINION OF COUNSEL FOR THE HOLDER, SATISFACTORY TO THE COMPANY,
THAT SUCH REGISTRATION IS NOT REQUIRED UNDER THE .ACT OR RECEIPT OF A NO-ACTION
LETTER FROM THE SECURITIES AND EXCHANGE COMMISSION.

                         ------------------------------

         WARRANT TO PURCHASE 54,000 SHARES SERIES B PREFERRED STOCK

                                                                   July 20 ,1995

         THIS CERTIFIES THAT, for value received, Lease Management Services,
Inc., ("Holder") is entitled to subscribe for and purchase fifty four thousand
(54,000) shares of the fully paid and nonassessable Series B Preferred Stock
("the Shares") of IntraBiotics Pharmaceuticals, Inc., a Delaware corporation
(the "Company"), at the Warrant Price (as hereinafter defined), subject to the
provisions and upon the terms and conditions hereinafter set forth. As used
herein, the term "Series B Preferred Stock" shall mean the Company's presently
authorized Series B Preferred Stock, and any stock into which such Series B
Preferred Stock may hereafter be exchanged.

1. WARRANT PRICE. The Warrant Price shall initially be one and 00/100 dollars
($1.00), subject to adjustment as provided in Section 7 below.

2. CONDITIONS TO EXERCISE. The purchase right represented by this Warrant may be
exercised at any time, or from time to time, in whole or in part during the term
commencing on the date hereof and ending on the earlier of:

         (a) 5:00 P.M. California time on the sixth annual anniversary of this
Warrant; or

         (b) the effective date of the merger of the Company with or into, the
consolidation of the Company with, or the sale by the Company of all or
substantially all of its assets to another corporation or other entity (other
than such a transaction wherein the shareholders of the Company retain or obtain
a majority of the voting capital stock of the surviving, resulting, or
purchasing corporation); provided that the Company shall notify the registered
Holder of this Warrant of the proposed effective date of the merger,
consolidation, or sale at least 60 days prior to the effectiveness thereof.

         In the event that, although the Company shall have given notice of a
transaction pursuant to subparagraph (b) hereof, the transaction does not close
on approximately the day specified by the Company, unless otherwise elected by
the Holder any exercise of the Warrant subsequent to the giving of such notice
shall be rescinded and the Warrant shall again be exercisable until terminated
in accordance with this Paragraph 2.


                                       1.

<PAGE>

3. METHOD OF EXERCISE; PAYMENT; ISSUANCE OF SHARES; ISSUANCE OF NEW WARRANT.

         (a) CASH EXERCISE. Subject to Section 2 hereof, the purchase right
represented by this Warrant may be exercised by the Holder hereof, in whole or
in part, by the surrender of this Warrant (with a duly executed Notice of
Exercise in the form attached hereto) at the principal office of the Company (as
set forth in Section 18 below) and by payment to the Company, by check, of an
amount equal to the then applicable Warrant Price per share multiplied by the
number of shares then being purchased. In the event of any exercise of the
rights represented by this Warrant, certificates for the shares of stock so
purchased shall be in the name of, and delivered to, the Holder hereof, or as
such Holder may direct (subject to the terms of transfer contained herein and
upon payment by such Holder hereof of any applicable transfer taxes). Such
delivery shall be made within 10 days after exercise of the Warrant and at the
Company's expense and, unless this Warrant has been fully exercised or expired,
a new Warrant having terms and conditions substantially identical to this
Warrant and representing the portion of the Shares, if any, with respect to
which this Warrant shall not have been exercised, shall also be issued to the
Holder hereof within 10 days after exercise of the Warrant.

         (b) NET ISSUE EXERCISE. In lieu of exercising this Warrant pursuant to
Section 3(a), Holder may elect to receive shares equal to the value of this
Warrant (or of any portion thereof remaining unexercised) by surrender of this
Warrant at the principal office of the Company together with notice of such
election, in which event the Company shall issue to Holder the number of shares
of the Company's Series B Preferred Stock computed using the following formula:

         X = Y (A-B)
             -------
                A

         Where X = the number of shares of Series B Preferred Stock to be issued
                   to Holder.

         Y = the number of shares of Series B Preferred Stock purchasable
             under this Warrant (at the date of such calculation).

         A = the fair market value of one share of the Company's Series B
             Preferred Stock (at the date of such calculation).

         B = Warrant exercise price (as adjusted to the date of such
             calculation).

         (c) FAIR MARKET VALUE. For purposes of this Section 3, Fair Market
Value of one share of the Company's Series B Preferred Stock shall mean:

                  (i) In the event of an Initial Public Offering per share Fair
Market Value for the Series B Preferred Stock shall be the Offering Price at
which the underwriters sell Common Stock to the public multiplied by the number
of shares of Common Stock into which each share of Series B Preferred Stock is
then convertible; or

                  (ii) If the Common Stock is traded on NASDAQ or
Over-The-Counter or on an exchange, the per share Fair Market Value for the
Series B Preferred Stock will be the average of the closing bid and asked prices
of the Common Stock quoted in the Over-The-


                                       2.

<PAGE>

Counter Market Summary or the closing price quoted on any exchange on which the
Series B Preferred Stock is listed, whichever is applicable, as published in the
Western Edition of The Wall Street Journal for the ten (10) trading days prior
to the date of determination of Fair Market Value multiplied by the number of
shares of Common Stock into which each share of Series B Preferred Stock is then
convertible; or

                  (iii) If the Company shall be subject to a merger, acquisition
or other consolidation in which the Company is not the surviving entity,
pursuant to Section 200), the per share Fair Market Value for the Series B
Preferred Stock shall be the value received per share of Series B Preferred
Stock by all Holders of the Series B Preferred Stock as determined by the Board
of Directors; or

                  (iv) In any other instance, the per share Fair Market Value
for the Series B Preferred Stock shall be as determined by the Board of
Directors in its reasonable business judgment.

         In the event of 3(c)(iii) or 3(c)(iv), above, the Company's Board of
Directors shall prepare a certificate, to be signed by an authorized Officer of
the Company, setting forth in reasonable detail the basis for and method of
determination of the per share Fair Market Value of the Series B Preferred
Stock. The Board will also certify to the Holder that this per share Fair Market
Value will be applicable to all holders of the Company's Series B Preferred
Stock. Such certification must be made to Holder at least thirty (30) business
days prior to the proposed effective date of the merger, consolidation, sale, or
other triggering event as defined in 3(c)(iii) and 3(c)(iv).

         (d) AUTOMATIC EXERCISE. To the extent this Warrant is not previously
exercised, it shall be automatically exercised in accordance with Sections 3(b)
and 3(c) hereof (even if not surrendered) immediately before: (i) its
expiration, or (ii) the consummation of any consolidation or merger of the
Company, or any sale or transfer of a majority of a company's assets pursuant to
Section 2(b).

4. REPRESENTATIONS AND WARRANTIES OF HOLDER AND RESTRICTIONS ON TRANSFER IMPOSED
BY THE SECURITIES ACT OF 1933.

         (a) REPRESENTATIONS AND WARRANTIES BY HOLDER. The Holder represents and
warrants to the Company with respect to this purchase as follows:

                  (i) The Holder has substantial experience in evaluating and
investing in private placement transactions of securities of companies similar
to the Company so that the Holder is capable of evaluating the merits and risks
of its investment in the Company and has the capacity to protect its interests.

                  (ii) The Holder is acquiring the Warrant and the Shares of
Series B Preferred Stock issuable upon exercise of the Warrant (collectively the
"Securities") for investment for its own account and not with a view to, or for
resale in connection with, any distribution thereof. The Holder understands that
the Securities have not been registered under the Act by reason of a specific
exemption from the registration provisions of the Act which depends upon, among
other things, the bona fide nature of the investment intent as expressed herein.
In this connection, the


                                       3.

<PAGE>

Holder understands that, in the view of the Securities and Exchange Commission
(the "SEC"), the statutory basis for such exemption may be unavailable if this
representation was predicated solely upon a present intention to hold the
Securities for the minimum capital gains period specified under tax statutes,
for a deferred sale, for or until an increase or decrease in the market price of
the Securities or for a period of one year or any other fixed period in the
future.

                  (iii) The Holder acknowledges that the Securities must be held
indefinitely unless subsequently registered under the Act or an exemption from
such registration is available. The Holder is aware of the provisions of Rule
144 promulgated under the Act ("Rule 144") which permits limited resale of
securities purchased in a private placement subject to the satisfaction of
certain conditions, including, in case the securities have been held for less
than three years, the existence of a public market for the shares, the
availability of certain public information about the Company, the resale
occurring not less than two years after a party has purchased and paid for the
security to be sold, the sale being through a "broker's transaction" or in a
transaction directly with a "market maker" (as provided by Rule 144(f)) and the
number of shares or other securities being sold during any three-month period
not exceeding specified limitations.

                  (iv) The Holder further understands that at the time the
Holder wishes to sell the Securities there may be no public market upon which
such a sale may be effected, and that even if such a public market exists, the
Company may not be satisfying the current public information requirements of
Rule 144, and that in such event, the Holder may be precluded from selling the
Securities under Rule 144 unless as a three-year minimum holding period has been
satisfied and b) the Holder was not at the time of the sale nor at any time
during the three-month period prior to such sale an affiliate of the Company.

                  (v) The Holder has had an opportunity to discuss the Company's
business, management and financial affairs with its management and an
opportunity to review the Company's facilities. The Holder understands that such
discussions, as well as the written information issued by the Company, were
intended to describe the aspects of the Company's business and prospects which
it believes to be material but were not necessarily a thorough or exhaustive
description.

         (b) LEGENDS. Each certificate representing the Securities shall be
endorsed with the following legend:

         THESE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF
         1933 AND MAY NOT BE TRANSFERRED UNLESS COVERED BY AN EFFECTIVE
         REGISTRATION STATEMENT UNDER SAID ACT, A "NO ACTION" LETTER FROM THE
         SECURITIES AND EXCHANGE COMMISSION WITH RESPECT TO SUCH TRANSFER, A
         TRANSFER MEETING THE REQUIREMENTS OF RULE 144 OF THE SECURITIES AND
         EXCHANGE COMMISSION, OR AN OPINION OF COUNSEL SATISFACTORY TO THE
         ISSUER TO THE EFFECT THAT ANY SUCH TRANSFER IS EXEMPT FROM SUCH
         REGISTRATION.


                                       4.

<PAGE>

         The Company need not register a transfer of Securities unless the
conditions specified in the foregoing legend are satisfied. The Company may also
instruct its transfer agent not to register the transfer of any of the Shares
unless the conditions specified in the foregoing legend are satisfied.

         (c) REMOVAL OF LEGEND AND TRANSFER RESTRICTIONS. The legend relating to
the Act endorsed on a certificate pursuant to paragraph 4(b) of this Warrant and
the stop transfer instructions with respect to the Securities represented by
such certificate shall be removed and the Company shall issue a certificate
without such legend to the Holder of the Securities if (i) the Securities are
registered under the Act and a prospectus meeting the requirements of Section 10
of the Act is available or (ii) the Holder provides to the Company an opinion of
counsel for the Holder reasonably satisfactory to the Company, or a no-action
letter or interpretive opinion of the staff of the SEC reasonably satisfactory
to the Company, to the effect that public sale, transfer or assignment of the
Securities may be without registration and without compliance with any
restriction such as Rule 144.

5. CONDITION OF TRANSFER OR EXERCISE OF WARRANT. It shall be a condition to any
transfer or exercise of this Warrant that at the time of such transfer or
exercise, the Holder shall provide the Company with a representation in writing
that the Holder or transferee is acquiring this Warrant and the shares of Series
B Preferred Stock to be issued upon exercise, for investment purposes only and
not with a view to any sale or distribution, or a statement of pertinent facts
coveting any proposed distribution. As a further condition to any transfer of
this Warrant or any or all of the shares of Series B Preferred Stock issuable
upon exercise of this Warrant, other than a transfer registered under the Act,
the Company must have received a legal opinion, in form and substance
satisfactory to the Company and its counsel, reciting the pertinent
circumstances surrounding the proposed transfer and stating that such transfer
is exempt from the registration and prospectus delivery requirements of the Act.
Each certificate evidencing the shares issued upon exercise of the Warrant or
upon any transfer of the shares (other than a transfer registered under the Act
or any subsequent transfer of shares so registered) shall, at the Company's
option, contain a legend in form and substance satisfactory to the Company and
its counsel, restricting the transfer of the shares to sales or other
dispositions exempt from the requirements of the Act.

         As further condition to each transfer, the transferee shall receive and
accept a Warrant, of like tenor and date, executed by the Company.

6. STOCK FULLY PAID; RESERVATION OF SHARES. All Shares which may be issued upon
the exercise of the rights represented by this Warrant will, upon issuance, be
fully paid and nonassessable, and free from all taxes, liens, and charges with
respect to the issue thereof. During the period within which the rights
represented by this Warrant may be exercised, the Company will at all times have
authorized, and reserved for issuance upon exercise of the purchase rights
evidenced by this Warrant, a sufficient number of shares of its Series B
Preferred Stock to provide for the exercise of the rights represented by this
Warrant.

7. ADJUSTMENT FOR CERTAIN EVENTS. In the event of changes in the outstanding
Series B Preferred Stock by reason of stock dividends, split-ups,
recapitalizations, reclassifications, conversions, mergers, consolidations,
combinations or exchanges of shares, separations, reorganizations, liquidations,
or the like, the number and class of shares available under the


                                       5.

<PAGE>

Warrant in the aggregate and the Warrant Price shall be correspondingly
adjusted, as appropriate, by the Board of Directors of the Company. The
adjustment shall be such as will give the Holder of this Warrant upon exercise
for the same aggregate Warrant Price the total number, class and kind of shares
as it would have owned had the Warrant been exercised prior to the event and had
it continued to hold such shares until after the event requiring adjustment.
Nothing herein shall be construed as providing Holder with antidilution rights
greater than the antidilution rights, if any, of the holders of the Series B
Preferred Stock generally, as set forth in the Company's Restated Articles of
Incorporation, as amended. No adjustment in the Warrant Price and/or the number
of Shares need be made if such adjustment would result in a change in the
Warrant Price of less than one cent ($0.01) or a change in the number of Shares
of less than one-hundredth (1/100th) of a share. Any adjustment less than these
amounts which is not made shall be carried forward and shall be made at the time
and together with any subsequent adjustment which, on a cumulative basis,
amounts to an adjustment of at least these amounts.

8. NOTICE OF ADJUSTMENTS. Whenever any Warrant Price shall be adjusted pursuant
to Section 7 hereof, the Company shall prepare a certificate signed by its chief
financial officer setting forth, in reasonable detail, the event requiring the
adjustment, the amount of the adjustment, the method by which such adjustment
was calculated, and the Warrant Price and number of shares issuable upon
exercise of the Warrant after giving effect to such adjustment, and shall cause
copies of such certificate to be mailed (by certified or registered mail, return
receipt required, postage prepaid) within thirty (30) days of such adjustment to
the Holder of this warrant as set forth in Section 18 hereof.

9. "MARKET STAND-OFF" AGREEMENT. Holder hereby agrees that for a period of 180
days following the effective date of the first registration statement of the
Company covering Series B Preferred stock (or other securities) to be sold on
its behalf in an underwritten public offering, it will not, to the extent
requested by the Company and any underwriter, sell or otherwise transfer or
dispose of (other than to donees or transferees who agree to be similarly bound)
any of the Shares at any time during such period except Series B Preferred stock
included in such registration; provided, however, that all officers and
directors of the Company who hold securities of the Company or options to
acquire securities of the Company and all other persons with registration rights
enter into similar agreements.

10. TRANSFERABILITY OF WARRANT. This Warrant is transferable one time only, in
whole and not in part, on the books of the Company at its principal office by
the registered Holder hereof upon surrender of this Warrant properly endorsed,
subject to compliance with applicable federal and state securities laws
(including the delivery of investment representation letters and legal opinions
reasonably satisfactory to the Company, if such are requested by the Company);
provided, however, that notwithstanding the foregoing, this Warrant may be
transferred to Holder's parent company or to an affiliate company as part of a
merger or consolidation and such transfer shall not count as the one permitted
transfer referred to above. The Company shall issue and deliver to the
transferee a new Warrant representing the Warrant so transferred. Upon any
partial transfer, the Company will issue and deliver to Holder a new Warrant
with respect to the Warrant not so transferred. Holder shall not have any right
to transfer any portion of this Warrant to any direct competitor of the Company.


                                       6.

<PAGE>

11. NO FRACTIONAL SHARES. No fractional share of Series B Preferred Stock will
be issued in connection with any exercise hereunder, but in lieu of such
fractional share the Company shall make a cash payment therefor upon the basis
of the Warrant Price then in effect.

12. CHARGES, TAXES AND EXPENSES. Issuance of certificates for shares of Series B
Preferred Stock upon the exercise of this Warrant shall be made without charge
to the Holder for any United States or state of the United States documentary
stamp tax or other incidental expense in reject of the issuance of such
certificate, all of which taxes and expenses shall be paid by the Company, and
such certificates shall be issued in the name of the Holder.

13. NO SHAREHOLDER RIGHTS UNTIL EXERCISE. This Warrant does not entitle the
Holder hereof to any voting rights or other rights as a shareholder of the
Company prior to the exercise hereof.

14. REGISTRY OF WARRANT. The Company shall maintain a registry showing the name
and address of the registered Holder of this Warrant. This Warrant may be
surrendered for exchange or exercise, in accordance with its terms, at such
office or agency of the Company, and the Company and Holder shall be entitled to
rely in all respects, prior to written notice to the contrary, upon such
registry.

15. LOSS, THEFT, DESTRUCTION OR MUTILATION OF WARRANT. Upon receipt by the
Company of evidence reasonably satisfactory to it of the loss, theft,
destruction or mutilation of this Warrant, and, in the case of loss, theft, or
destruction, of indemnity reasonably satisfactory to it, and, if mutilated, upon
surrender and cancellation of this Warrant, the Company will execute and deliver
a new Warrant, having terms and conditions substantially identical to this
Warrant, in lieu hereof.

16.      MISCELLANEOUS.

         (a) ISSUE DATE. The provisions of this Warrant shall be construed and
shall be given effect in all respect as if it had been issued and delivered by
the Company on the date hereof.

         (b) SUCCESSORS. This Warrant shall be binding upon any successors or
assigns of the Company.

         (c) GOVERNING LAW. This Warrant shall be governed by and construed in
accordance with the laws of the State of California.

         (d) HEADINGS. The headings used in this Warrant are used for
convenience only and are not to be considered in construing or interpreting this
Warrant.

         (e) SATURDAYS, SUNDAYS, HOLIDAYS. If the last or appointed day for the
taking of any action or the expiration of any right required or granted herein
shall be a Saturday or a Sunday or shall be a legal holiday in the State of
California, then such action may be taken or such right may be exercised on the
next succeeding day not a legal holiday.

17. NO IMPAIRMENT. The Company will not, by amendment of its Articles of
Incorporation or any other voluntary action, avoid or seek to avoid the
observance or performance of any of the terms of this Warrant, but will at all
times in good faith assist in the carrying out of all such


                                       7.

<PAGE>

terms and in the taking of all such action as may be necessary or appropriate in
order to protect the rights of the Holder hereof against impairment.

18. ADDRESSES. Any notice required or permitted hereunder shall be in writing
and shall be mailed by overnight courier, registered or certified mail, return
receipt required, and postage pre-paid, or otherwise delivered by hand or by
messenger, addressed as set forth below, or at such other address as the Company
or the Holder hereof shall have furnished to the other party.

         If to the Company:         Intra Biotics Pharmaceuticals, Inc
                                    816 Kifer Road
                                    Sunnyvale, CA 94086
                                    Attn: Chief Financial Officer

         If to the Holder:          Lease Management Services, Inc.
                                    2500 Sand Hill Road, Ste 101
                                    Menlo Park, CA 94025
                                    Attn: Barbara B. Kaiser, EVP/GM

         IN WITNESS WHEREOF, Kenneth J. Kelley has caused this Warrant to be
executed by its officers thereunto duly authorized.

Dated as of July 20, 1995.

                                                      /s/ Kenneth J. Kelley
                                                 -------------------------------
                                                 By: Kenneth J. Kelley
                                                    ----------------------------
                                                 Title: President and CEO
                                                       -------------------------


                                       8.