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                                                                     EXHIBIT 4.5

                            WARRANT TO PURCHASE STOCK

THIS WARRANT AND THE SHARES ISSUABLE HEREUNDER HAVE NOT BEEN REGISTERED UNDER
THE SECURITIES ACT OF 1933, AS AMENDED (THE "ACT"), OR THE SECURITIES LAWS OF
ANY STATE AND, EXCEPT AND PURSUANT TO THE PROVISIONS OF ARTICLE 5 BELOW, MAY NOT
BE OFFERED, SOLD OR OTHERWISE TRANSFERRED, PLEDGED OR HYPOTHECATED UNLESS AND
UNTIL REGISTERED UNDER SAID ACT AND APPLICABLE STATE SECURITIES LAW OR, IN THE
OPINION OF LEGAL COUNSEL IN FORM AND SUBSTANCE SATISFACTORY TO THE ISSUER OF
THESE SECURITIES, SUCH OFFER, SALE OR TRANSFER, PLEDGE OR HYPOTHECATION IS
EXEMPT FROM REGISTRATION.

Corporation:               I-Flow Corporation, a Delaware corporation

Number of Shares:          15,625

Class of Stock:            Common Stock

Initial Exercise Price:    $ 3.84

Issue Date:                May 8, 2003

Expiration Date:           May 8, 2010

         THIS WARRANT CERTIFIES THAT, for the agreed upon value of $1.00 and for
other good and valuable consideration, SILICON VALLEY BANK ("Holder") is
entitled to purchase the number of fully paid and nonassessable shares of the
class of securities (the "Shares") of the company (the "Company") at the Warrant
Price, all as set forth above and as adjusted pursuant to Article 2 of this
Warrant, subject to the provisions and upon the terms and conditions set forth
in this Warrant.

ARTICLE 1. EXERCISE.

         1.1 Method of Exercise. Holder may exercise this Warrant by delivering
a duly executed Notice of Exercise in substantially the form attached as
Appendix 1 to the principal office of the Company. Unless Holder is exercising
the conversion right set forth in Article 1.2, Holder shall also deliver to the
Company a check, wire transfer (to an account designated by the Company), or
other from of payment acceptable to the Company for the aggregate Warrant Price
for the Shares being purchased.

         1.2 Conversion Right. In lieu of exercising this Warrant as specified
in Article 1.1, Holder may from time to time convert this Warrant, in whole or
in part, into a number of Shares determined by dividing (a) the aggregate fair
market value of the Shares or other securities otherwise issuable upon exercise
of this Warrant minus the aggregate Warrant Price of such

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Shares by (b) the fair market value of one Share. The fair market value of the
Shares shall be determined pursuant to Article 1.3.

         1.3 Fair Market Value. If the Company's common stock is traded in a
public market and the shares are common stock, the fair market value of each
Share shall be the closing price of a Share reported for the business day
immediately before Holder delivers its Notice of Exercise to the Company (or in
the instance where the Warrant is exercised immediately prior to the
effectiveness of the Company's initial public offering, the "price to public"
per share price specified in the final prospectus relating to such offering). If
the Company's common stock is not traded in a public market, the Board of
Directors of the Company shall determine fair market value in its reasonable
good faith judgment.

         1.4 Delivery of Certificate and New Warrant. Promptly after Holder
exercises or converts this Warrant and, if applicable, the Company receives
payment of the aggregate Warrant Price, the Company shall deliver to Holder
certificates for the Shares acquired and, if this Warrant has not been fully
exercised or converted and has not expired, a new Warrant representing the
Shares not so acquired.

         1.5 Replacement of Warrants. On receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction or mutilation of
this Warrant and, in the case of loss, theft or destruction, on delivery of an
indemnity agreement reasonably satisfactory in form and amount to the Company
or, in the case of mutilation, or surrender and cancellation of this Warrant,
the Company shall execute and deliver, in lieu of this Warrant, a new warrant of
like tenor.

         1.6  Treatment of Warrant Upon Acquisition of Company.

              1.6.1 "Acquisition". For the purpose of this Warrant,
"Acquisition" means any sale, license, or other disposition of all or
substantially all of the assets of the Company, or any reorganization,
consolidation, or merger of the Company where the holders of the Company's
securities before the transaction beneficially own less than 50% of the
outstanding voting securities of the surviving entity after the transaction.

              1.6.2 Treatment of Warrant at Acquisition.

A) Upon the written request of the Company, Holder agrees that, in the event of
an Acquisition in which the sole consideration is cash, either (a) Holder shall
exercise its conversion or purchase right under this Warrant and such exercise
will be deemed effective immediately prior to the consummation of such
Acquisition or (b) if Holder elects not to exercise the Warrant, this Warrant
will expire upon the consummation of such Acquisition. The Company shall provide
the Holder with written notice of its request relating to the foregoing
(together with such reasonable information as the Holder may request in
connection with such contemplated Acquisition giving rise to such notice), which
is to be delivered to Holder not less than ten (10) days prior to the closing of
the proposed Acquisition.

B) Upon the written request of the Company, Holder agrees that, in the event of
an Acquisition that is an "arms length" sale of all or substantially all of the
Company's assets (and only its assets) to a third party that is not an Affiliate
(as defined below) of the Company (a "True Asset Sale"), either (a) Holder shall
exercise its conversion or purchase right under this Warrant and such exercise
will be deemed effective immediately prior to the consummation of such
Acquisition or (b) if Holder elects not to exercise the Warrant, this Warrant
will continue until the Expiration Date if the Company continues as a going
concern following the closing of any such True Asset Sale. The Company shall
provide the Holder with written notice of its request

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relating to the foregoing (together with such reasonable information as the
Holder may request in connection with such contemplated Acquisition giving rise
to such notice), which is to be delivered to Holder not less than ten (10) days
prior to the closing of the proposed Acquisition.

C) Upon the closing of any Acquisition other than those particularly described
in subsections (A) and (B) above, the successor entity shall assume the
obligations of this Warrant, and this Warrant shall be exercisable for the same
securities, cash, and property as would be payable for the Shares issuable upon
exercise of the unexercised portion of this Warrant as if such Shares were
outstanding on the record date for the Acquisition and subsequent closing. The
Warrant Price and/or number of Shares shall be adjusted accordingly.

As used herein "Affiliate" shall mean any person or entity that owns or controls
directly or indirectly ten (10) percent or more of the stock of Company, any
person or entity that controls or is controlled by or is under common control
with such persons or entities, and each of such person's or entity's officers,
directors, joint venturers or partners, as applicable.

ARTICLE 2. ADJUSTMENTS TO THE SHARES.

         2.1 Stock Dividends, Splits, Etc. If the Company declares or pays a
dividend on the Shares payable in common stock, or other securities, then upon
exercise of this Warrant, for each Share acquired, Holder shall receive, without
cost to Holder, the total number and kind of securities to which Holder would
have been entitled had Holder owned the Shares of record as of the date the
dividend occurred. If the Company subdivides the Shares by reclassification or
otherwise into a greater number of shares or takes any other action which
increase the amount of stock into which the Shares are convertible, the number
of shares purchasable hereunder shall be proportionately increased and the
Warrant Price shall be proportionately decreased. If the outstanding shares are
combined or consolidated, by reclassification or otherwise, into a lesser number
of shares, the Warrant Price shall be proportionately increased and the number
of Shares shall be proportionately decreased.

         2.2 Reclassification, Exchange, Combinations or Substitution. Upon any
reclassification, exchange, substitution, or other event that results in a
change of the number and/or class of the securities issuable upon exercise or
conversion of this Warrant, Holder shall be entitled to receive, upon exercise
or conversion of this Warrant, the number and kind of securities and property
that Holder would have received for the Shares if this Warrant had been
exercised immediately before such reclassification, exchange, substitution, or
other event. The Company or its successor shall promptly issue to Holder an
amendment to this Warrant setting forth the number and kind of such new
securities or other property issuable upon exercise or conversion of this
Warrant as a result of such reclassification, exchange, substitution or other
event that results in a change of the number and/or class of securities issuable
upon exercise or conversion of this Warrant. The amendment to this Warrant shall
provide for adjustments which shall be as nearly equivalent as may be
practicable to the adjustments provided for in this Article 2 including, without
limitation, adjustments to the Warrant Price and to the number of securities or
property issuable upon exercise of the new Warrant. The provisions of this
Article 2.2 shall similarly apply to successive reclassifications, exchanges,
substitutions, or other events.

         2.3 Adjustments for Diluting Issuances. The Warrant Price and the
number of Shares issuable upon exercise of this Warrant shall be subject to
adjustment, from time to time in the manner set forth in the Company's
Certificate of Incorporation as if the Shares were issued and outstanding on and
as of the date of any such required adjustment. The provisions set forth for the
Shares in the Company's Certificate of Incorporation relating to the above in

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effect as of the Issue Date may not be amended, modified or waived, without the
prior written consent of Holder unless such amendment, modification or waiver
affects the rights associated with the Shares in the same manner as such
amendment, modification or waiver affects the rights associated with all other
shares of the same series and class as the Shares granted to the Holder.

         2.4 No Impairment. The Company shall not, by amendment of its
Certificate of Incorporation or through a reorganization, transfer of assets,
consolidation, merger, dissolution, issue, or sale of securities or any other
voluntary action, avoid or seek to avoid the observance or performance of any of
the terms to be observed or performed under this Warrant by the Company, but
shall at all times in good faith assist in carrying out of all the provisions of
this Article 2 and in taking all such action as may be necessary or appropriate
to protect Holder's rights under this Article against impairment.

         2.5 Fractional Shares. No fractional Shares shall be issuable upon
exercise or conversion of the Warrant and the number of Shares to be issued
shall be rounded down to the nearest whole Share. If a fractional share interest
arises upon any exercise or conversion of the Warrant, the Company shall
eliminate such fractional share interest by paying Holder the amount computed by
multiplying the fractional interest by the fair market value of a full Share.

         2.6 Certificate as to Adjustments. Upon each adjustment of the Warrant
Price, the Company shall promptly notify Holder in writing, and, at the
Company's expense, promptly compute such adjustment, and furnish Holder with a
certificate of its Chief Financial Officer setting forth such adjustment and the
facts upon which such adjustment is based. The Company shall, upon written
request, furnish Holder a certificate setting forth the Warrant Price in effect
upon the date thereof and the series of adjustments leading to such Warrant
Price.

ARTICLE 3. REPRESENTATIONS AND COVENANTS OF THE COMPANY.

         3.1 Representations and Warranties. The Company represents and warrants
to the Holder as follows:

              (a) The initial Warrant Price referenced on the first page of this
Warrant is not greater than the fair market value of the Shares as of the date
of this Warrant.

              (b) All Shares which may be issued upon the exercise of the
purchase right represented by this Warrant, and all securities, if any, issuable
upon conversion of the Shares, shall, upon issuance, be duly authorized, validly
issued, fully paid and nonassessable, and free of any liens and encumbrances
except for restrictions on transfer provided for herein or under applicable
federal and state securities laws.

              (c) The Capitalization Table previously provided to Holder remains
true and complete as of the Issue Date.

         3.2 Notice of Certain Events. If the Company proposes at any time (a)
to declare any dividend or distribution upon any of its stock, whether in cash,
property, stock, or other securities and whether or not a regular cash dividend;
(b) to offer for sale additional shares of any class or series of the Company's
stock; (c) to effect any reclassification or recapitalization of any of its
stock; (d) to merge or consolidate with or into any other corporation, or sell,
lease, license, or convey all or substantially all of its assets, or to
liquidate, dissolve or wind up; or (e) offer holders of registration rights the
opportunity to participate in an underwritten public offering of

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the company's securities for cash, then, in connection with each such event, the
Company shall give Holder: (1) at least 10 days prior written notice of the date
on which a record will be taken for such dividend, distribution, or subscription
rights (and specifying the date on which the holders of common stock will be
entitled thereto) or for determining rights to vote, if any, in respect of the
matters referred to in (c) and (d) above; (2) in the case of the matters
referred to in (c) and (d) above at least 10 days prior written notice of the
date when the same will take place (and specifying the date on which the holders
of common stock will be entitled to exchange their common stock for securities
or other property deliverable upon the occurrence of such event); and (3) in the
case of the matter referred to in (e) above, the same notice as is given to the
holders of such registration rights.

         3.3 Registration Rights. The Company agrees that the Shares shall have
certain incidental, or "Piggyback," registration rights pursuant to and as set
forth in the Registration Rights Agreement in favor of Holder being entered into
concurrently herewith.

         3.4 No Shareholder Rights. Except as provided in this Warrant, the
Holder will not have any rights as a shareholder of the Company until the
exercise of this Warrant.

ARTICLE 4. REPRESENTATIONS, WARRANTIES OF THE HOLDER. The Holder represents and
warrants to the Company as follows:

         4.1 Purchase for Own Account. This Warrant and the securities to be
acquired upon exercise of this Warrant by the Holder will be acquired for
investment for the Holder's account, not as a nominee or agent, and not with a
view to the public resale or distribution within the meaning of the Act. Holder
also represents that the Holder has not been formed for the specific purpose of
acquiring this Warrant or the Shares.

         4.2 Disclosure of Information. The Holder has received or has had full
access to all the information it considers necessary or appropriate to make an
informed investment decision with respect to the acquisition of this Warrant and
its underlying securities. The Holder further has had an opportunity to ask
questions and receive answers from the Company regarding the terms and
conditions of the offering of this Warrant and its underlying securities and to
obtain additional information (to the extent the Company possessed such
information or could acquire it without unreasonable effort or expense)
necessary to verify any information furnished to the Holder or to which the
Holder has access.

         4.3 Investment Experience. The Holder understands that the purchase of
this Warrant and its underlying securities involves substantial risk. The Holder
has experience as an investor in securities of companies in the development
stage and acknowledges that the Holder can bear the economic risk of such
Holder's investment in this Warrant and its underlying securities and has such
knowledge and experience in financial or business matters that the Holder is
capable of evaluating the merits and risks of its investment in this Warrant and
its underlying securities and/or has a preexisting personal or business
relationship with the Company and certain of its officers, directors or
controlling persons of a nature and duration that enables the Holder to be aware
of the character, business acumen and financial circumstances of such persons.

         4.4 Accredited Investor Status. The Holder is an "accredited investor"
within the meaning of Regulation D promulgated under the Act.

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         4.5 The Act. The Holder understands that this Warrant and the Shares
issuable upon exercise or conversion hereof have not been registered under the
Act in reliance upon a specific exemption therefrom, which exemption depends
upon, among other things, the bona fide nature of the Holder's investment intent
as expressed herein. The Holder understands that this Warrant and the Shares
issued upon any exercise or conversion hereof must be held indefinitely unless
subsequently registered under the 1933 Act and qualified under applicable state
securities laws, or unless exemption from such registration and qualification
are otherwise available.

ARTICLE 5. MISCELLANEOUS.

         5.1 Term: This Warrant is exercisable in whole or in part at any time
and from time to time on or before the Expiration Date.

         5.2 Legends.This Warrant and the Shares (and the securities issuable,
directly or indirectly, upon conversion of the Shares, if any) shall be
imprinted with a legend in substantially the following form:

          THIS WARRANT AND THE SHARES ISSUABLE HEREUNDER HAVE NOT BEEN
          REGISTERED UNDER THE ACT, OR THE SECURITIES LAWS OF ANY STATE AND,
          EXCEPT AND PURSUANT TO THE PROVISIONS OF ARTICLE 5 BELOW, MAY NOT
          BE OFFERED, SOLD OR OTHERWISE TRANSFERRED, PLEDGED OR HYPOTHECATED
          UNLESS AND UNTIL REGISTERED UNDER SAID ACT AND APPLICABLE STATE
          SECURITIES LAW OR, IN THE OPINION OF LEGAL COUNSEL IN FORM AND
          SUBSTANCE SATISFACTORY TO THE ISSUER OF THESE SECURITIES, SUCH
          OFFER, SALE OR TRANSFER, PLEDGE OR HYPOTHECATION IS EXEMPT FROM
          REGISTRATION.

         5.3 Compliance with Securities Laws on Transfer. This Warrant and the
Shares issuable upon exercise of this Warrant (and the securities issuable,
directly or indirectly, upon conversion of the Shares, if any) may not be
transferred or assigned in whole or in part without compliance with applicable
federal and state securities laws by the transferor and the transferee
(including, without limitation, the delivery of investment representation
letters and legal opinions reasonably satisfactory to the Company, as reasonably
requested by the Company). The Company shall not require Holder to provide an
opinion of counsel if the transfer is to Silicon Valley Bancshares (Holder's
parent company) or any other affiliate of Holder. Additionally, the Company
shall also not require an opinion of counsel if there is no material question as
to the availability of current information as referenced in Rule 144(c), Holder
represents that it has complied with Rule 144(d) and (e) in reasonable detail,
the selling broker represents that it has complied with Rule 144(f), and the
Company is provided with a copy of Holder's notice of proposed sale.

         5.4 Transfer Procedure. Upon receipt by Holder of the executed Warrant,
Holder will transfer all of this Warrant to Silicon Valley Bancshares, Holder's
parent company, by execution of an Assignment substantially in the form of
Appendix 2. Subject to the provisions of Article 5.3 and upon providing Company
with written notice, Silicon Valley Bancshares and any subsequent Holder may
transfer all or part of this Warrant or the Shares issuable upon exercise of
this Warrant (or the Shares issuable directly or indirectly, upon conversion of
the Shares, if any) to any transferee, provided, however, in connection with any
such transfer, Silicon Valley Bancshares or any subsequent Holder will give the
Company notice of the portion of the Warrant being transferred with the name,
address and taxpayer identification

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number of the transferee and Holder will surrender this Warrant to the Company
for reissuance to the transferee(s) (and Holder if applicable). The Company may
refuse to transfer this Warrant or the Shares to any person who directly
competes with the Company, unless, in either case, the stock of the Company is
publicly traded.

         5.5 Notices. All notices and other communications from the Company to
the Holder, or vice versa, shall be deemed delivered and effective when given
personally or mailed by first-class registered or certified mail, postage
prepaid, at such address as may have been furnished to the Company or the
Holder, as the case may (or on the first business day after transmission by
facsimile) be, in writing by the Company or such holder from time to time.
Effective upon receipt of the fully executed Warrant and the initial transfer
described in Article 5.4 above, all notices to the Holder shall be addressed as
follows until the Company receives notice of a change of address in connection
with a transfer or otherwise:

                           Silicon Valley Bancshares
                           Attn: Treasury Department
                           3003 Tasman Drive, HA 200
                           Santa Clara, CA 95054
                           Telephone: 408-654-7400
                           Facsimile: 408-496-2405

         Notice to the Company shall be addressed as follows until the Holder
receives notice of a change in address:

                           I-Flow Corporation
                           Attn: Chief Financial Officer
                           20202 Windrow Drive
                           Lake Forest, California 92630
                           Telephone: 949-206-2700
                           Facsimile: 949-206-2603

         5.6 Waiver. This Warrant and any term hereof may be changed, waived,
discharged or terminated only by an instrument in writing signed by the party
against which enforcement of such change, waiver, discharge or termination is
sought.

         5.7 Attorney's Fees. In the event of any dispute between the parties
concerning the terms and provisions of this Warrant, the party prevailing in
such dispute shall be entitled to collect from the other party all costs
incurred in such dispute, including reasonable attorney's fees.

         5.8 Automatic Conversion upon Expiration. In the event that, upon the
Expiration Date, the fair market value of one Share (or other security issuable
upon the exercise hereof) as determined in accordance with Section 1.3 above is
greater than the Exercise Price in effect on such date, then this Warrant shall
automatically be deemed on and as of such date to be converted pursuant to
Section 1.2 above as to all Shares (or such other securities) for which it shall
not previously have been exercised or converted, and the Company shall promptly
deliver a certificate representing the Shares (or such other securities) issued
upon such conversion to the Holder.

         5.9 Counterparts. This Warrant may be executed in counterparts, all of
which together shall constitute one and the same agreement.

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         5.10 Governing Law. This Warrant shall be governed by and construed in
accordance with the laws of the State of California, without giving effect to
its principles regarding conflicts of law.

"COMPANY"

I-FLOW CORPORATION                         I-FLOW CORPORATION

By: _________________________________      By: ________________________________

Name: Donald M. Earhart                    Name: James R. Talevich
          (Print)                                     (Print)
Title: Chairman, President and CEO         Title: Chief Financial Officer

"HOLDER"

SILICON VALLEY BANK

By: _________________________________

Name: Gary Reagan
   (Print)
Title: Vice President

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                                   APPENDIX 1

                               NOTICE OF EXERCISE

         1. Holder elects to purchase ___________ shares of the Common Stock of
I-Flow Corporation pursuant to the terms of the attached Warrant, and tenders
payment of the purchase price of the shares in full.

        [or]

     1. Holder elects to convert the attached Warrant into Shares/cash [strike
one] in the manner specified in the Warrant. This conversion is exercised for
_____________________ of the Shares covered by the Warrant.

     [Strike paragraph that does not apply.]

     2. Please issue a certificate or certificates representing the shares in
the name specified below:

                           ___________________________________________
                                    Holders Name
                           ___________________________________________

                           ___________________________________________
                                    (Address)

     3. By its execution below and for the benefit of the Company, Holder hereby
restates each of the representations and warranties in Article 4 of the Warrant
as the date hereof.

                               HOLDER:
                               _________________________

                                                   By: _________________________
                                                   Name: _______________________
                                                   Title: ______________________

                                                   (Date): _____________________

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                                   APPENDIX 2

                                   ASSIGNMENT

         For value received, Silicon Valley Bank hereby sells, assigns and
transfers unto

                       Name:    Silicon Valley Bancshares
                       Address: 3003 Tasman Drive (HA-200)
                                   Santa Clara, CA 95054

                       Tax ID:     91-1962278

         that certain Warrant to Purchase Stock issued by I-Flow Corporation
         (the "Company"), on May __, 2003 (the "Warrant") together with all
         rights, title and interest therein.

                                         SILICON VALLEY BANK

                                         By: ___________________________________
                                         Name: _________________________________
                                         Title: ________________________________

Date: May __, 2003
By its execution below, and for the benefit of the Company, Silicon Valley
Bancshares makes each of the representations and warranties set forth in Article
4 of the Warrant as of the date hereof.

                                         SILICON VALLEY BANCSHARES

                                         By: ___________________________________
                                         Name: _________________________________
                                         Title: ________________________________

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