<PAGE>

                                                                     EXHIBIT 4.5

THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE BEEN ACQUIRED FOR INVESTMENT
AND HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933 OR ANY STATE
SECURITIES LAWS. SUCH SECURITIES MAY NOT BE SOLD OR TRANSFERRED IN THE ABSENCE
OF SUCH REGISTRATION OR AN EXEMPTION THEREFROM UNDER SAID ACT AND ANY APPLICABLE
STATE SECURITIES LAWS.

                               WARRANT TO PURCHASE

                  52,000 SHARES OF SERIES C PREFERRED STOCK OF

                                  AEROGEN, INC.

                          (Void after October 14, 2004)

This certifies that VENTURE LENDING & LEASING INC., a Maryland corporation, or
assigns (the "Holder"), for value received, is entitled to purchase from
AEROGEN, INC., a California corporation (the "Company"), up to 52,000 fully
paid and nonassessable shares ("Warrant Shares") of the Company's Series C
Preferred Stock ("Preferred Stock") for cash at a price of $1.00 per share (the
"Stock Purchase Price") at any time or from time to time up to and including
5:00 p.m. (Pacific time) on October 14, 2004 (the "Expiration Date"), upon
surrender to the Company at its principal office at 1310 Orleans Drive,
Sunnyvale, CA 94089 , (or at such other location as the Company may advise
Holder in writing) of this Warrant properly endorsed with the Form of
Subscription attached hereto duly filled in and signed and upon payment in cash
or by certified bank check of the aggregate Stock Purchase Price for the number
of shares for which this Warrant is being exercised determined in accordance
with the provisions hereof. Notwithstanding the above, this warrant shall be
exercisable for only 13,000 Warrant Shares upon the date hereof. This warrant
shall vest and become exercisable for additional shares to a maximum of 52,000
shares, on a pro rata basis as the Company makes draw downs above $200,000.00
under the Loan Agreement between the Company and the initial Holder dated
October 14, 1997 ("Loan Agreement"). The Stock Purchase Price and the number of
shares purchasable hereunder are subject to adjustment as provided in Section 4
of this Warrant.

This Warrant is subject to the following terms and conditions:

         1.       EXERCISE; ISSUANCE OF CERTIFICATES; PAYMENT FOR SHARES.

               (a) Unless an election is made pursuant to clause (b) of this
Section 1, this Warrant shall be exercisable, subject to the vesting provisions
described above, at the option of the Holder, at any time or from time to time,
on or before the Expiration Date for all or any portion of the shares of
Preferred Stock (but not for a fraction of a share) which may be purchased
hereunder for the Stock Purchase Price multiplied by the number of shares to be
purchased. In the event, however, that pursuant to the Company's Articles of
Incorporation, as amended, an event causing automatic conversion of the
Company's Preferred Stock shall have occurred prior to the exercise of the
Warrant, in whole or in part, then this Warrant shall be exercisable, subject to
the vesting provisions described above, for the number of shares of

                                       1.
<PAGE>


Common Stock of the Company into which the Preferred Stock not purchased upon
any prior exercise of the Warrant would have been so converted (and, where
the context requires, reference to "Preferred Stock" shall be deemed to
include such Common Stock). The Company agrees that the shares of Preferred
Stock purchased under this Warrant shall be and are deemed to be issued to
the holder hereof as the record owner of such shares as of the close of
business on the date on which the form of subscription shall have been
delivered and payment made for such shares. Subject to the provisions of
Section 2, certificates for the shares of Preferred Stock so purchased,
together with any other securities or property to which the Holder hereof is
entitled upon such exercise, shall be delivered to the Holder hereof by the
Company at the Company's expense within a reasonable time after the rights
represented by this Warrant have been so exercised. Except as provided in
clause (b) of this Section 1, in case of a purchase of less than an the
shares which may be purchased under this Warrant, the Company shall cancel
this Warrant and execute and deliver a new Warrant or Warrants of like tenor
for the balance of the shares purchasable under the Warrant surrendered upon
such purchase to the Holder hereof within a reasonable time. Each stock
certificate so delivered shall be in such denominations of Preferred Stock as
may be requested by the Holder hereof and shall be registered in the name of
such Holder or such other name as shall be designated by such Holder, subject
to the limitations contained in Section 2.

               (b) In the event the Company has registered its Common Stock
pursuant to a registration statement filed by the Company under the Securities
Act of 1933, as amended (the "Securities Act"), the Holder, in lieu of
exercising this Warrant by the payment of the Stock Purchase Price pursuant to
clause (a) of this Section 1, may elect, at any time on or before the Expiration
Date, to receive that number of shares of Preferred Stock equal to the quotient
of: (i) the difference between (A) the Per Share Price (as hereinafter defined)
of the Preferred Stock, less (B) the Stock Purchase Price then in effect,
multiplied by the number of shares of Preferred Stock the Holder would otherwise
have been entitled to purchase hereunder pursuant to clause (a) of this Section
1 (or such lesser number of shares as the Holder may designate in the case of a
partial exercise of this Warrant); over (ii) the Per Share Price. Election to
exercise under this section (b) may be made by delivering a signed form of
subscription to the Company via facsimile (upon receipt of appropriate
confirmation), to be followed by delivery of the warrant.

               (c) For purposes of clause (b) of this Section 1, "Per Share
Price" means the product of: (i) the greater of (A) the closing price of the
Company's Common Stock as quoted by NASDAQ or listed on any exchange, whichever
is applicable, as published in the Western Edition of THE WALL STREET JOURNAL
for the trading day immediately prior to the date of the Holder's election
hereunder or, (B) if applicable at the time of or in connection with the
exercise under clause (b) of this Section 1, the gross sales price of one share
of the Company's Common Stock pursuant to a registered public offering or that
amount which shareholders of the Company will receive for each share of Common
Stock pursuant to a merger, reorganization or sale of assets; and (ii) that
number of shares of Common Stock into which each share of Preferred Stock is
convertible. If the Company's Common Stock is not quoted by NASDAQ or listed on
any exchange, the Per Share Price of the Preferred Stock (or the equivalent
number of shares of Common Stock into which such Preferred Stock is convertible)
shall be determined by the Company's Board of Directors.

                                       2.
<PAGE>


         2.       LIMITATION ON TRANSFER.

               (a) The Warrant and the Preferred Stock shall not be transferable
except upon the conditions specified in this Section 2, which conditions are
intended to insure compliance with the provisions of the Securities Act. Each
holder of this Warrant or the Preferred Stock issuable hereunder will cause any
proposed transferee of the Warrant or Preferred Stock to agree to take and hold
such securities subject to the provisions and upon the conditions specified in
this Section 2.

               (b) Each certificate representing (i) this Warrant, (ii) the
Preferred Stock, (iii) shares of the Company's Common Stock issued upon
conversion of the Preferred Stock and (iv) any other securities issued in
respect to the Preferred Stock or Common Stock issued upon conversion of the
Preferred Stock upon any stock split, stock dividend, recapitalization, merger,
consolidation or similar event; shall (unless otherwise permitted by the
provisions of this Section 2 or unless such securities have been registered
under the Securities Act or sold under Rule 144) be stamped or otherwise
imprinted with a legend substantially in the following form (in addition to any
legend required under applicable state securities Laws):

THE SECURITIES REPRESENTED BY THIS CERTIFICATE HAVE BEEN ACQUIRED FOR INVESTMENT
AND HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933 OR ANY STATE
SECURITIES LAWS. SUCH SECURITIES MAY NOT BE SOLD OR TRANSFERRED IN THE ABSENCE
OF SUCH REGISTRATION OR AN EXEMPTION THEREFROM UNDER SAID ACT AND ANY APPLICABLE
STATE SECURITIES LAWS.

               (c) The Holder of this Warrant and each person to whom this
Warrant is subsequently transferred represents and warrants to the Company (by
acceptance of such transfer) that it will not transfer the Warrant (or
securities issuable upon exercise hereof unless a registration statement under
the Securities Act was in effect with respect to such securities at the time of
issuance thereof) except pursuant to (i) an effective registration statement
under the Securities Act, (ii) Rule 144 under the Securities Act (or any other
rule under the Securities Act relating to the disposition of securities), or
(iii) an opinion of counsel, reasonably satisfactory to counsel for the Company,
that an exemption from such registration is available.

               (d) At any time that amounts are outstanding under the Loan
Agreement this Warrant may only be transferred if it is transferred in whole
(but not in part) to a party who has been transferred all of the rights and
obligations of the initial Holder under such Loan Agreement.

         3. SHARES TO BE FULLY PAID; RESERVATION OF SHARES. The Company
covenants and agrees that all shares of Preferred Stock which may be issued upon
the exercise of the rights represented by this Warrant will, upon issuance, be
duly authorized, validly issued, fully paid and nonassessable and free from all
preemptive rights of any shareholder and free of all taxes, liens and charges
with respect to the issue thereof. The Company further covenants and agrees that
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 the
purpose of issue or transfer upon exercise of the subscription rights evidenced
by this Warrant, a sufficient number of shares of

                                       3.
<PAGE>


authorized but unissued Preferred Stock, or other securities and property,
when and as required to provide for the exercise of the rights represented by
this Warrant. The Company will take all such action as may be necessary to
assure that such shares of Preferred Stock may be issued as provided herein
without violation of any applicable law or regulation, or of any requirements
of any domestic securities exchange upon which the Preferred Stock may be
listed. The Company will not take any action which would result in any
adjustment of the Stock Purchase Price (as defined in Section 4 hereof) (i)
if the total number of shares of Preferred Stock issuable after such action
upon exercise of all outstanding warrants, together with all shares of
Preferred Stock then outstanding and all shares of Preferred Stock then
issuable upon exercise of all options and upon the conversion of all
convertible securities then outstanding, would exceed the total number of
shares of Preferred Stock then authorized by the Company's Articles of
Incorporation, or (ii) if the total number of shares of Common Stock issuable
after such action upon the conversion of all such shares of Preferred Stock
together with all shares of Common Stock then outstanding and then issuable
upon exercise of all options and upon the conversion of all convertible
securities then outstanding would exceed the total number of shares of Common
Stock then authorized by the Company's Articles of Incorporation.

         4. ADJUSTMENT OF STOCK PURCHASE PRICE NUMBER OF SHARES. The Stock
Purchase Price and the number of shares purchasable upon the exercise of this
Warrant shall be subject to adjustment from time to time upon the occurrence of
certain events described in this Section 4. Upon each adjustment of the Stock
Purchase Price, the Holder of this Warrant shall thereafter be entitled to
purchase, at the Stock Purchase Price resulting from such adjustment the number
of shares obtained by multiplying the Stock Purchase Price in effect immediately
prior to such adjustment by the number of shares purchasable pursuant hereto
immediately prior to such adjustment, and dividing the product thereof by the
Stock Purchase Price resulting from such adjustment.

          4.1 SUBDIVISION OR COMBINATION OF STOCK.  In case the Company shall
at any time subdivide its outstanding shares of Preferred Stock into a greater
number of shares, the Stock Purchase Price in effect immediately prior to such
subdivision shall be proportionately reduced, and conversely, in case the
outstanding shares of Preferred Stock of the Company shall be combined into a
smaller number of shares, the Stock Purchase Price in effect immediately prior
to such combination shall be proportionately increased.

          4.2 DIVIDENDS IN PREFERRED STOCK, OTHER STOCK, PROPERTY,
RECLASSIFICATION. If at any time or from time to time the holders of Preferred
Stock (or any shares of stock or other securities at the time receivable upon
the exercise of this Warrant) shall have received or become entitled to receive,
without payment therefor,

               (a) Preferred Stock, or any shares of stock or other securities
whether or not such securities are at any time directly or indirectly
convertible into or exchangeable for Preferred Stock, or any rights or options
to subscribe for, purchase or otherwise acquire any of the foregoing by way of
dividend or other distribution, or

               (b) any cash paid or payable otherwise than as a cash dividend,
or

                                       4.
<PAGE>


               (c) Preferred Stock or other or additional stock or other
securities or property (including cash) by way of spinoff, split-up,
reclassification, combination of shares or similar corporate rearrangement,
(other than shares of Preferred Stock issued as a stock split adjustments in
respect of which shall be covered by the terms of Section 4.1 above),

Then and in each such case, the Holder hereof shall, upon the exercise of this
Warrant be entitled to receive, in addition to the number of shares of Preferred
Stock receivable thereupon, and without payment of any additional consideration
therefore, the amount of stock and other securities and property (including cash
in the cases referred to in clauses (b) and (c) above) which such Holder would
hold on the date of such exercise had he been the holder of record of such
Preferred Stock as of the date on which holders of Preferred Stock received or
became entitled to receive such shares and/or all other additional stock and
other securities and property.

          4.3  REORGANIZATION, RECLASSIFICATION, CONSOLIDATION, MERGER OR SALE.

               (a) If any capital reorganization of the capital stock of the
Company, or any consolidation or merger of the Company with another corporation,
or the sale of all or substantially all of its assets to another corporation
(except for a consolidation, merger or sale of assets described in section
4.3(b) shall be effected in such a way that holders of Preferred Stock shall be
entitled to receive stock, securities or assets with respect to or in exchange
for Preferred Stock, then, as a condition of such reorganization,
reclassification, consolidation, merger or sale, lawful and adequate provisions
shall be made whereby the holder hereof shall thereafter have the right to
purchase and receive (in lieu of the shares of the Preferred Stock of the
Company immediately theretofore purchasable and receivable upon the exercise of
the rights represented hereby) such shares of stock, securities or assets as may
be issued or payable with respect to or in exchange for a number of outstanding
shares of such Preferred Stock equal to the number of shares of such stock
immediately theretofore purchasable and receivable upon the exercise of the
rights represented hereby. In any such case, appropriate provision shall be made
with respect to the rights and interests of the bolder of this Warrant to the
end that the provisions hereof (including, without limitation, provisions for
adjustments of the Stock Purchase Price and of the number of shares purchasable
and receivable upon the exercise of this Warrant) shall thereafter be
applicable, as nearly as may be possible, in relation to any shares of stock,
securities or assets thereafter deliverable upon the exercise hereof. The
Company will not effect any such consolidation, merger or sale unless, prior to
the consummation thereof, the successor corporation (if other than the Company)
resulting from such consolidation or the corporation purchasing such assets
shall assume by written instrument, executed and mailed or delivered to the
registered Holder hereof at the last address of such Holder appearing on the
books of the Company, the obligation to deliver to such Holder such shares of
stock, securities or assets as, in accordance with the foregoing provisions,
such Holder may be entitled to purchase.

               (b) Notwithstanding anything in Section 4.3(a) to the contrary,
this Warrant shall terminate upon the consummation of any consolidation or
merger with another corporation or any sale of all or substantially all of the
assets of the Company in which the stockholders of the Company immediately
before such merger, consolidation or sale do not hold more than 50% of the
outstanding voting equity interests of the surviving or acquiring entity
following such merger, consolidation or sale, unless the surviving or acquiring
entity specifically assumes the Company's obligations hereunder.

                                       5.
<PAGE>


          4.4 ADJUSTMENTS TO SERIES C PREFERRED STOCK. Upon the occurrence of an
adjustment or readjustment of the Conversion Price, as such term is defined in
the Company's Amended and Restated Articles of Incorporation (the "Restated
Articles"), of the Series C Preferred Stock, the Company shall give to the
registered holder of this Warrant a copy of the Certificate as to Adjustments
provided for in Section 5.3.8 of the Restated Articles, setting, forth the
Current Conversion Price, determined as provided for in the Section 5 of Article
Five of the Restated Articles, of the Series C Preferred Stock to be received
upon exercise of this Warrant.

          4.5 NOTICE OF ADJUSTMENT. Upon any adjustment of the Stock Purchase
Price, and/or any increase or decrease in the number of shares purchasable upon
the exercise of this Warrant the Company shall give written notice thereof, by
first class mail, postage prepaid, addressed to the registered holder of this
Warrant at the address of such holder as shown on the books of the Company. The
notice shall be signed by the Company's chief financial officer and shall state
the Stock Purchase Price resulting from such adjustment and the increase or
decrease, if any, in the number of shares purchasable at such price upon the
exercise of this Warrant, setting forth in reasonable detail the method of
calculation and the facts upon which such calculation is based.

          4.6 OTHER NOTICES. If at any time:

               (a) the Company shall declare any cash dividend upon its
Preferred Stock;

               (b) the Company shall declare any dividend upon its Preferred
Stock payable in stock or make any special dividend or other distribution to the
holders of its Preferred Stock;

               (c) there shall be any capital reorganization or reclassification
of the capital stock of the Company, or consolidation or merger of the Company
with, or sale of all or substantially all of its assets to, another corporation;

               (d) there shall be a voluntary or involuntary dissolution,
liquidation or winding-up of the Company, or

then, in any one or more of said cases, the Company shall give, by first
class mail, postage prepaid, addressed to the holder of this Warrant at the
address of such holder as shown on the books of the Company, (i) at least 20
day's prior written notice of the date on which the books of the Company
shall close or a record shall be taken for such dividend, distribution or
subscription rights or for determining rights to vote in respect of any such
reorganization, reclassification, consolidation, merger, sale, dissolution,
liquidation or winding-up, or other action and (ii) in the case of any such
reorganization, reclassification, consolidation, merger, sale, dissolution,
liquidation or winding-up, or other action, at least 20 day's written notice
of the date when the same shall take place. Any notice given in accordance
with the foregoing clause (i) shall also specify, in the case of any such
dividend, distribution or subscription rights, the date on which the holders
of Preferred Stock shall be entitled thereto. Any notice given in accordance
with the foregoing clause (ii) shall also specify the date on which the
holders of Preferred Stock shall be entitled to exchange their Preferred
Stock for securities or other property deliverable upon such

                                       6.
<PAGE>


reorganization, reclassification, consolidation, merger, sale, dissolution,
liquidation or winding-up, or other action as the case may be. In the event
the majority of Preferred Stock Holders waive the above notices, then Holder
of the Warrant shall be deemed to waive this notice period.

          4.7 CERTAIN EVENTS. If any change in the outstanding Preferred Stock
of the Company or any other event occurs as to which the other provisions of
this Section 4 are not strictly applicable or if strictly applicable would not
fairly protect the purchase rights of the Holder of the Warrant in accordance
with the essential intent and principles of such provisions, then the Board of
Directors of the Company shall make an adjustment in the number and class of
shares available under the Warrant, the Stock Purchase Price and/or the
application of such provisions, in accordance with such essential intent and
principles, so as to protect such purchase rights as aforesaid. The adjustment
shall be such as will give the Holder of the Warrant upon exercise for the same
aggregate Stock Purchase Price the total number, class and kind of shares as he
would have owned had the Warrant been exercised prior to the event and had he
continued to hold such shares until after the event requiring adjustment.

         5. ISSUE TAX. The issuance of certificates for shares of Preferred
Stock upon the exercise of the Warrant shall be made without charge to the
Holder of the Warrant for any issue tax in respect thereof; provided, however,
that the Company shall not be required to pay any tax which may be payable in
respect of any transfer involved in the issuance and delivery of any certificate
in a name other than that of the then Holder of the Warrant being exercised.

         6. CLOSING OF BOOKS. The Company will at no time close its transfer
books against the transfer of any Warrant or of any shares of Preferred Stock
issued or issuable upon the exercise of any warrant in any manner which
interferes with the timely exercise of this Warrant.

         7. NO VOTING OR DIVIDEND RIGHTS; LIMITATION OF LIABILITY. Nothing
contained in this Warrant shall be construed as conferring upon the Holder
hereof the right to vote or to consent as shareholder in respect of meetings of
shareholders for the election of directors of the Company or any other matters
or any rights whatsoever as a shareholder of the Company. No dividends or
interest shall be payable or accrued in respect of this Warrant or the interest
represented hereby or the shares purchasable hereunder until, and only to the
extent that, this Warrant shall have been exercised. No provisions hereof, in
the absence of affirmative action by the holder to purchase shares of Preferred
Stock, and no mere enumeration herein of the rights or privileges of the Holder
hereof, shall give rise to any liability of such Holder for the Stock Purchase
Price or as a shareholder of the Company, whether such liability is asserted by
the Company or by its creditors.

         8. INTENTIONALLY DELETED.

         9. REGISTRATION RIGHTS. By its execution hereof, the Holder shall
become a party to the Second Amended and Restated Information Rights Agreement
dated April 11, 1997 by and among the Company and the Holders listed therein and
hereby agrees to be bound by the terms and conditions thereof. Provided however
that the Holder shall not be entitled to a right of first offer under Section
16, thereof.

                                       7.
<PAGE>


         10. RIGHTS AND OBLIGATIONS SURVIVE EXERCISE OF WARRANT. The rights and
obligations of the Company, of the Holder of this Warrant and of the holder of
shares of Preferred Stock issued upon exercise of this Warrant, contained in
Sections 6, 8 and 9 shall survive the exercise of this Warrant.

         11. MODIFICATION AND WAIVER. This Warrant and any provision hereof may
be changed, waived, discharged or terminated only by an instrument in writing
signed by the party against which enforcement of the same is sought.

         12. NOTICES. Any notice, request or other document required or
permitted to be given or delivered to the holder hereof or the Company shall be
deemed to have been given (i) upon receipt if delivered personally or by courier
(ii) upon confirmation of receipt if by telecopy or (iii) three business days
after deposit in the US mail, with postage prepaid and certified or registered,
to each such holder at its address as shown on the books of the Company or to
the Company at the address indicated therefor in the first paragraph of this
Warrant.

         13. BINDING EFFECT ON SUCCESSORS. This Warrant shall be binding upon
any corporation succeeding the Company by merger, consolidation or acquisition
of all or substantially all of the Company's assets. All of the obligations of
the Company relating to the Preferred Stock issuable upon the exercise of this
Warrant shall survive the exercise and termination of this Warrant. All of the
covenants and agreements of the Company shall inure to the benefit of the
successors and assign of the holder hereof. The Company will, at the time of the
exercise of this Warrant, in whole or in part, upon request of the Holder hereof
but at the Company's expense, acknowledge in writing its continuing obligation
to the Holder hereof in respect of any rights (including, without limitation,
any right to registration of the shares of Common Stock) to which the holder
hereof shall continue to be entitled after such exercise in accordance with this
Warrant; provided, that the failure of the holder hereof to make any such
request shall not affect the continuing obligation of the Company to the Holder
hereof in respect of such rights.

         14. DESCRIPTIVE HEADINGS AND GOVERNING LAW. The descriptive headings of
the several sections and paragraphs of this Warrant are inserted for convenience
only and do not constitute a part of this Warrant. This Warrant shall be
construed and enforced in accordance with, and the rights of the parties shall
be governed by, the laws of the State of California.

         15. LOST WARRANTS OR STOCK CERTIFICATES. The Company represents and
warrants to the Holder hereof that upon receipt of evidence reasonably
satisfactory to the Company of the loss, theft, destruction, or mutilation of
any Warrant or stock certificate and, in the case of any such loss, theft or
destruction, upon receipt of an indemnity reasonably satisfactory to the
Company, or in the case of any such mutilation upon surrender and cancellation
of such Warrant or stock certificate, the Company at its expense will make and
deliver a new Warrant or stock certificate, of like tenor, in lieu of the lost,
stolen, destroyed or mutilated Warrant or stock certificate.

         16. FRACTIONAL SHARES. No fractional shares shall be issued upon
exercise of this Warrant. The Company shall, in lieu of issuing any fractional
share, pay the holder entitled to such fraction a sum in cash equal to such
fraction multiplied by the then effective Stock Purchase Price.

                                       8.
<PAGE>


         17.  REPRESENTATIONS OF HOLDER. With respect to this Warrant, Holder
represents and warrants to the Company as follows:

          17.1 EXPERIENCE. It is experienced in evaluating and investing in
companies engaged in businesses similar to that of the Company; it understands
that investment in the Warrant involves substantial risks; it has made detailed
inquiries concerning the Company, its business and services, its officers and
its personnel; the officers of the Company have made available to Holder any and
all written information it has requested; the officers of the Company have
answered to Holder's satisfaction all inquiries made by it; in making this
investment it has relied upon information made available to it by the Company;
and it has such knowledge and experience in financial and business matters that
it is capable of evaluating the merits and risks of investment in the Company
and it is able to bear the economic risk of that investment.

          17.2 INVESTMENT. It is acquiring the Warrant for investment for its
own account and not with a view to, or for resale in connection with, any
distribution thereof. It understands that the Warrant, the shares of Preferred
Stock issuable upon exercise thereof and the shares of Common Stock issuable
upon conversion of the Preferred Stock, have not been registered under the
Securities Act of 1933, as amended, nor qualified under applicable state
securities laws.

          17.3 RULE 144. It acknowledges that the Warrant, the Preferred Stock
and the Common Stock must be held indefinitely unless they are subsequently
registered under the Securities Act or an exemption from such registration is
available. It has been advised or is aware of the provisions of Rule 144
promulgated under the Securities Act.

          17.4 ACCESS TO DATA. It has had an opportunity to discuss the
Company's business, management and financial affairs with the Company's
management and has had the opportunity to inspect the Company's facilities.

          17.5 ACCREDITED INVESTOR. Holder represents that it is an Accredited
Investor as defined in Rule 501(a) of Regulation D promulgated under the
Security Act.

         18. ADDITIONAL REPRESENTATIONS AND COVENANTS OF THE Company. The
Company hereby represents, warrants and agrees as follows:

          18.1 CORPORATE POWER. The Company has all requisite corporate power
and corporate authority to issue this Warrant and to carry out and perform its
obligations hereunder.

          18.2 AUTHORIZATION. All corporate action on the part of the Company,
its directors and shareholders necessary for the authorization, execution,
delivery and performance by the Company of this has been taken. This Warrant is
a valid and binding obligation of the Company, enforceable in accordance with
its terms.

          18.3 OFFERING. Subject in part to the truth and accuracy of Holder's
representations set forth in Section 17 hereof, the offer, issuance and sale of
the Warrant is, and the issuance of Preferred Stock upon exercise of the Warrant
and the issuance of Common Stock upon conversion of the Preferred Stock will be
exempt from the registration requirements of the Securities Act, and are exempt
from the qualification requirements of any applicable state

                                       9.
<PAGE>


securities laws; and neither the Company nor anyone acting on its behalf will
take any action hereafter that would cause the loss of such exemptions.

          18.4 STOCK ISSUANCE. Upon exercise of the Warrant, the Company will
use its best efforts to cause stock certificates representing the shares of
Preferred Stock purchased pursuant to the exercise to be issued in the
individual names of Holder, its nominees or assignees, as appropriate at the
time of such exercise. Upon conversion of the shares of Preferred Stock to
shares of Common Stock, the Company will issue the Common Stock in the
individual names of Holder, its nominees or assignees. as appropriate.

          18.5 ARTICLES AND BY-LAWS. The Company has provided Holder with true
and complete copies of the Company's Articles or Certificate of Incorporation,
By-Laws, and each Certificate of Determination or other charter document
setting, forth any rights, preferences and privileges of Company's capital
stock, each as amended and in effect on the date of issuance of this Warrant.

          18.6 CONVERSION OF PREFERRED STOCK. As of the date hereof, each share
of the Preferred Stock is convertible into one share of the Common Stock.



IN WITNESS WHEREOF, the Company has caused this Warrant to be duly executed by
its officers, thereunto duly authorized this 14th day of October, 1997.

AEROGEN, INC.



By: /s/ Andrew Heath
   ---------------------------
Title: President

                                       10.
<PAGE>





                              FORM OF SUBSCRIPTION

                  (To be signed only upon exercise of Warrant)

To:
   --------------------------------

The undersigned, the holder of the within Warrant, hereby irrevocably elects to
exercise the purchase right represented by such Warrant for, and to purchase
thereunder, _____________________ (____) shares of Preferred Stock of
_______________________ and herewith makes payment of Dollars ($_____) therefor,
and requests that the certificates for such shares be issued in the name of,
and delivered to,_______________________,       whose address is
_____________________________________.

The undersigned represents that it is acquiring such Preferred Stock for its own
account for investment and not with a view to or for sale in connection with any
distribution thereof (subject, however, to any requirement of law that the
disposition thereof shall at all times be within its control.

                                    DATED:
                                          ------------------

                                    ------------------------
                                    (Signature must conform to name of Holder
                                    as specified on the face of the Warrant or
                                    as specified in an Assignment)

                                    (Address)

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

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



(1) Insert here the number of shares called for on the face of the Warrant (or,
in the case of a partial exercise, the portion thereof as to which the Warrant
is being exercised), in either case without making any adjustment for additional
Preferred Stock or any other stock or other securities or property or cash
which, pursuant to the adjustment provisions of the Warrant, may be deliverable
upon exercise.

                                       11.
<PAGE>



                                   ASSIGNMENT

FOR VALUE RECEIVED, the undersigned, the holder of the within Warrant, hereby
sells, assigns and transfers all of the rights of the undersigned under the
within Warrant, with respect to the number of shares of Preferred Stock covered
thereby set forth hereinbelow, unto:

NAME OF ASSIGNEE                  ADDRESS                NO. OF SHARES
--------------------------------------------------------------------------------




                                  Dated:
                                        -----------------------


                                  -----------------------------
                                  (Signature must conform to name of
                                  Holder as specified on the face of the
                                  Warrant or as specified in an
                                  Assignment)

                                       12.
<PAGE>


                                   EXHIBIT "A"

         This Exhibit is incorporated by reference into that certain Warrant
dated October 14 , 1997, issued by Aerogen, Inc., a California corporation (the
"Company"), to VENTURE LENDING & LEASING, INC., a Maryland corporation (the
"Holder").

         This certifies that the Holder is entitled to purchase from the Company
___________ (___________) fully paid and nonassessable shares of the Company's
_______________ Stock at a price of ___________ Dollars ($_________) per share
(the "Stock Purchase Price"). The Stock Purchase Price and the number of shares
purchasable under the Warrant remain subject to adjustment as provided in
Section 4 of the Warrant.



         IN WITNESS WHEREOF, the Company and the Holder have executed this
Exhibit to the Warrant this ____ day of ___________, 199____.

Aerogen, Inc.


By:
   ----------------------------
Name:
     --------------------------
Title:
      -------------------------

VENTURE LENDING & LEASING, INC.

By:
   ----------------------------
Name:
     --------------------------
Title:
      -------------------------
                                       13.