<PAGE>

                                                                     Exhibit 4.3


THIS WARRANT HAS NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED, OR APPLICABLE STATE SECURITIES LAWS AND MAY NOT BE SOLD, OFFERED FOR
SALE, TRANSFERRED, PLEDGED OR OTHERWISE DISPOSED OF UNLESS IT HAS BEEN
REGISTERED UNDER THOSE LAWS OR UNLESS THE COMPANY HAS RECEIVED AN OPINION OF
COUNSEL SATISFACTORY TO IT THAT AN EXEMPTION FROM REGISTRATION UNDER EACH OF
THOSE LAWS IS AVAILABLE.

THIS WARRANT IS SUBJECT TO CANCELATION UNDER CERTAIN CIRCUMSTANCES SET FORTH IN
SECTION 9 HEREOF.

THIS WARRANT MAY NOT BE TRANSFERRED EXCEPT AS PROVIDED IN SECTION 24.

No. WB-                               Right to Purchase _______ Shares of Common
                                      Stock of Valentis, Inc.


                                 VALENTIS, INC.

                     COMMON STOCK PURCHASE WARRANT, CLASS B


          VALENTIS, INC., a Delaware corporation (the "Company"), hereby
certifies that, for value received, [INSERT NAME OF HOLDER] or registered
assigns (the "Holder"), is entitled, subject to the terms set forth below, to
purchase from the Company at any time or from time to time on or after the
Issuance Date and before 5:00 p.m., New York City time, on the Expiration Date
(such capitalized term and all other capitalized terms used herein having the
respective meanings provided herein), _____ fully paid and nonassessable shares
of Common Stock at a purchase price per share equal to the Purchase Price. The
number of such shares of Common Stock and the Purchase Price are subject to
adjustment as provided in this Warrant.

          As used herein the following capitalized terms, unless the context
otherwise requires, have the following respective meanings:




<PAGE>

          "Aggregate Purchase Price" means at any time an amount equal to the
     product obtained by multiplying (x) the Purchase Price TIMES (y) the number
     of shares of Common Stock for which this Warrant may be exercised at such
     time.

          "Average Market Price" means the arithmetic average of the Market
     Price during any period of twenty (20) consecutive Trading Days.

          "Business Day" means any day other than a Saturday, Sunday or other
     day on which commercial banks in The City of New York are authorized or
     required by law to remain closed.

          "Cancelation Date" has the meaning provided in Section 9(b).

          "Certificate of Designations" shall have the meaning provided in the
     Subscription Agreement.

          "Common Stock" means the Common Stock, $.001 par value, of the
     Company, or any shares of capital stock of the Company into which such
     shares shall be changed or reclassified after the Issuance Date.

          "Common Stock Equivalents" means any warrant, option, subscription or
     purchase right with respect to shares of Common Stock, any security
     convertible into, exchangeable for, or otherwise entitling the holder
     thereof to acquire, shares of Common Stock or any warrant, option,
     subscription or purchase right with respect to any such convertible,
     exchangeable or other security.

          "Company" shall include Valentis, Inc., a Delaware corporation, and
     any corporation that shall succeed to or assume the obligations of
     Valentis, Inc. hereunder in accordance with the terms hereof.

          "Current Fair Market Value" means when used with respect to the Common
     Stock as of a specified date with respect to each share of Common Stock,
     the average of the closing prices of the Common Stock sold on all
     securities exchanges (including the Nasdaq and the Nasdaq SmallCap) on
     which the Common Stock may at the time be listed, or, if there have been no
     sales on any such exchange on such day, the average of the highest bid and
     lowest asked prices on all such exchanges at the end of such day, or, if on
     such day the Common Stock is not so listed, the average of the
     representative bid and asked prices quoted in the NASDAQ System as of 4:00
     p.m., New York City time, or, if on such day the Common Stock is not quoted
     in the NASDAQ System, the average of the highest bid and lowest asked price
     on such day in the domestic over-the-counter market as reported by the
     National Quotation Bureau, Incorporated, or any similar successor
     organization, in each such case averaged over a period of five Trading Days
     consisting of the day as of which the Current Fair Market Value of Common
     Stock is being determined (or if such day is not a Trading Day, the Trading
     Day next preceding such day) and the four consecutive Trading Days prior to
     such day. If on the date for which Current Fair Market Value is to be
     determined the Common Stock is not listed on any securities exchange or
     quoted in the NASDAQ System or the over-the-counter market, the Current
     Fair Market Value of Common Stock shall be the greater of (i) the


                                       2
<PAGE>

     highest price per share of Common Stock at which the Company has sold
     shares of Common Stock or Common Stock Equivalents within 365 days prior to
     the date of such determination and (ii) the highest price per share which
     the Company could then obtain from a willing buyer (not an employee or
     director of the Company at the time of determination) for shares of Common
     Stock sold by the Company, from authorized but unissued shares, as
     determined in good faith by the Board of Directors.

          "Expiration Date" means the fourth anniversary of the Issuance Date.

          "Issuance Date" means the date of original issuance of this Warrant.

          "Market Price" shall have the meaning provided in the Certificate of
     Designations.

          "Nasdaq" means the Nasdaq National Market.

          "Nasdaq SmallCap" means the Nasdaq SmallCap Market.

          "1934 Act" means the Securities Exchange Act of 1934, as amended.

          "1933 Act" means the Securities Act of 1933, as amended.

          "Other Securities" means any stock (other than Common Stock) and other
     securities of the Company or any other Person which the Holder at any time
     shall be entitled to receive, or shall have received, on the exercise of
     this Warrant, in lieu of or in addition to Common Stock, or which at any
     time shall be issuable or shall have been issued in exchange for or in
     replacement of Common Stock or Other Securities pursuant to Section 4.

          "Other Subscription Agreements" means the several Subscription
     Agreements, dated as of the date of the Subscription Agreement, by and
     between the Company and the several buyers named therein.

          "Other Warrants" means the Warrants and the Class A Warrants issued on
     the Issuance Date pursuant to the Subscription Agreement and the Other
     Subscription Agreements.

          "Person" means an individual, partnership, corporation, limited
     liability company, trust or unincorporated organization, or a government or
     a governmental agency or political subdivision.

          "Purchase Price" means $10.25, subject to adjustment as provided in
     this Warrant.

          "QIB" means a "qualified institutional buyer" as defined in Rule 144A.

          "Registration Statement" shall have the meaning provided in the
     Subscription Agreement.


                                       3
<PAGE>

          "Reorganization Event" means the occurrence of any one or more of the
     following events:

          (i)   any consolidation, merger or similar transaction of the Company
     or any Subsidiary with or into another entity (other than a merger or
     consolidation or similar transaction of a Subsidiary into the Company or a
     wholly-owned Subsidiary); or the sale or transfer of all or substantially
     all of the assets of the Company and the Subsidiaries in a single
     transaction or a series of related transactions; or

          (ii)  the occurrence of any transaction or event in connection with
     which all or substantially all the Common Stock shall be exchanged for,
     converted into, acquired for or constitute the right to receive securities
     of any other Person (whether by means of an exchange offer, liquidation,
     tender offer, consolidation, merger, share exchange, combination,
     reclassification, recapitalization, or otherwise); or

          (iii) the acquisition by a Person or group of Persons acting in
     concert as a partnership, limited partnership, syndicate or group, as a
     result of a tender or exchange offer, open market purchases, privately
     negotiated purchases or otherwise, of beneficial ownership of securities of
     the Company representing 50% or more of the combined voting power of the
     outstanding voting securities of the Company ordinarily (and apart from
     rights accruing in special circumstances) having the right to vote in the
     election of directors.

          "Restricted Securities" means securities that are not eligible for
     resale pursuant to Rule 144(k) under the 1933 Act (or any successor
     provision).

          "Rule 144A" means Rule 144A as promulgated under the 1933 Act.

          "SEC" means the Securities and Exchange Commission.

          "Series A Preferred Stock" means the Series A Convertible Redeemable
     Preferred Stock, par value $0.001 per share, of the Company issued pursuant
     to the Subscription Agreement and the Other Subscription Agreements.

          "Subscription Agreement" means the Subscription Agreement, dated as of
     November __, 2000, by and between the Company and the original Holder of
     this Warrant.

          "Subsidiary" means any corporation or other entity of which a majority
     of the capital stock or other ownership interests having ordinary voting
     power to elect a majority of the board of directors or other persons
     performing similar functions are at the time directly or indirectly owned
     by the Company.

          "Target Price" means $23.99, provided that in the event of an
adjustment in the Purchase Price, the Target Price shall be adjusted
proportionately.

                                       4
<PAGE>

          "Tender Offer" means a tender offer, exchange offer or other offer by
     the Company to repurchase outstanding shares of its capital stock.

          "Trading Day" means a day on which the national securities exchange,
     the Nasdaq or the Nasdaq SmallCap which then constitutes the principal
     securities market for the Common Stock is open for general trading.

          "Transaction Documents" shall have the meaning provided in the
     Subscription Agreement.

          "Warrant" means this Warrant and any Warrant or Warrants which may be
     issued pursuant to Section 4 or 5 hereof in substitution or exchange for or
     upon transfer of this Warrant, any Warrant which may be issued pursuant to
     Section 2 hereof upon partial exercise of this Warrant and any Warrant
     which may be issued pursuant to Section 6 hereof upon the loss, theft,
     destruction or mutilation of this Warrant.

          "Warrant Shares" means the shares of Common Stock, as adjusted from
     time to time in accordance with Section 8 hereof, deliverable upon exercise
     of this Warrant.

          1.        EXERCISE OF WARRANT.

          1.1       EXERCISE. This Warrant may be exercised by the Holder in
full at any time or in part from time to time for three years starting on
December 5, 2001 by (x) surrendering this Warrant to the Company, (y) giving
a subscription form in the form of Exhibit 1 to this Warrant (duly executed
by the Holder) to the Company, and (z) making payment, in cash or by
certified or official bank check payable to the order of the Company, or by
wire transfer of funds to the account of the Company, in either case, in the
amount obtained by multiplying (a) the number of shares of Common Stock
designated by the Holder in the subscription form by (b) the Purchase Price
then in effect. On any partial exercise the Company will forthwith issue and
deliver to or upon the order of the Holder a new Warrant or Warrants of like
tenor, in the name of the Holder or as the Holder (upon payment by the Holder
of any applicable transfer taxes) may request, providing in the aggregate on
the face or faces thereof for the purchase of the number of shares of Common
Stock for which such Warrant or Warrants may still be exercised. The
subscription form may be surrendered by telephone line facsimile transmission
to such telephone number for the Company as shall have been specified in
writing to the Holder by the Company; PROVIDED, HOWEVER, that if the
subscription form is given to the Company by telephone line facsimile
transmission the Holder shall send an original of such subscription form to
the Company within ten Business Days after such subscription form is so given
to the Company; PROVIDED FURTHER, HOWEVER, that any failure or delay on the
part of the Holder in giving such original of any subscription form shall not
affect the validity or the date on which such subscription form is so given
by telephone line facsimile transmission.

          1.2       NET ISSUANCE. Notwithstanding anything to the contrary
contained in Section 1.1, the Holder may elect to exercise this Warrant, in
whole or in part, by receiving shares of Common Stock having an aggregate
Current Fair Market Value equal to the net issuance value (as determined below)
of this Warrant, or any part hereof, upon surrender of the subscription form
annexed hereto (duly executed by the Holder) to the Company (followed by


                                       5
<PAGE>

surrender of this Warrant to the Company within three Trading Days after
surrender of such subscription form), in which event the Company shall issue to
the Holder a number of shares of Common Stock computed using the following
formula:

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


          where:     X =    the number of shares of Common Stock to be issued to
                            the Holder

                     Y =    the number of shares of Common Stock as to which
                            this Warrant is to be exercised

                     A =    the Current Fair Market Value of one share of Common
                            Stock calculated as of the last Trading Day
                            immediately preceding the exercise of this Warrant

                     B =    the Purchase Price

          2.        DELIVERY OF STOCK CERTIFICATES, ETC., ON EXERCISE. As soon
as practicable after the exercise of this Warrant, and in any event within three
Trading Days thereafter, the Company at its expense (including the payment by it
of any applicable issue or stamp taxes) will cause to be issued in the name of
and delivered to the Holder, or as the Holder (upon payment by the Holder of any
applicable transfer taxes) may direct, a certificate or certificates for the
number of fully paid and nonassessable shares of Common Stock (or Other
Securities) to which the Holder shall be entitled on such exercise, in such
denominations as may be requested by the Holder, plus, in lieu of any fractional
share to which the Holder would otherwise be entitled, cash equal to such
fraction multiplied by the then Current Fair Market Value of one full share,
together with any other stock or other securities or any property (including
cash, where applicable) to which the Holder is entitled upon such exercise
pursuant to Section 1 or otherwise. Upon exercise of this Warrant as provided
herein, the Company's obligation to issue and deliver the certificates for
Common Stock shall be absolute and unconditional, irrespective of the absence of
any action by the Holder to enforce the same, any waiver or consent with respect
to any provision hereof, the recovery of any judgment against any Person or any
action to enforce the same, any failure or delay in the enforcement of any other
obligation of the Company to the Holder, or any setoff, counterclaim,
recoupment, limitation or termination, or any breach or alleged breach by the
Holder or any other Person of any obligation to the Company or any violation or
alleged violation of law by the Holder or any other Person, and irrespective of
any other circumstance which might otherwise limit such obligation of the
Company to the Holder in connection with such exercise. If the Company fails to
issue and deliver the certificates for the Common Stock to the Holder pursuant
to the first sentence of this paragraph as and when required to do so, in
addition to any other liabilities the Company may have hereunder and under
applicable law, the Company shall pay or reimburse the Holder on demand for all
out-of-pocket expenses including, without limitation, fees and expenses of legal
counsel incurred by the Holder as a result of such failure.

          2.        ADJUSTMENT FOR DIVIDENDS IN OTHER STOCK, PROPERTY, ETC.;
RECLASSIFICATION, ETC. In case at any time or from time to time, all the holders
of Common Stock


                                       6
<PAGE>

(or Other Securities) shall have received, or (on or after the record date fixed
for the determination of stockholders eligible to receive) shall have become
entitled to receive, without payment therefor,

          (a)  other or additional stock, rights, warrants or other securities
     or property by way of dividend, or

          (b)  any cash, or

          (c)  other or additional stock, rights, warrants or other securities
     or property (including cash) by way of spin-off, split-up,
     reclassification, recapitalization, combination of shares or similar
     corporate rearrangement,

other than additional shares of Common Stock (or Other Securities) issued as a
stock dividend or in a stock-split (adjustments in respect of which are provided
for in Section 6), then and in each such case the Holder, on the exercise hereof
as provided in Section 1, shall be entitled to receive the amount of stock,
rights, warrants and other securities and property (including cash) which the
Holder would hold on the date of such exercise if on the date thereof the Holder
had been the holder of record of the number of shares of Common Stock called for
on the face of this Warrant and had thereafter, during the period from the date
thereof to and including the date of such exercise, retained such shares and all
such other or additional stock, rights, warrants and other securities and
property (including cash) receivable by the Holder as aforesaid during such
period, giving effect to all adjustments called for during such period by
Section 4.

          4.   EXERCISE UPON A REORGANIZATION EVENT. In case of any
Reorganization Event the Company shall, as a condition precedent to the
consummation of the transactions constituting, or announced as, such
Reorganization Event, cause effective provisions to be made so that the Holder
shall have the right thereafter, by exercising this Warrant (in lieu of the
shares of Common Stock of the Company and Other Securities or property
purchasable and receivable upon exercise of the rights represented hereby
immediately prior to such transaction) to purchase the kind and amount of shares
of stock and other securities and property (including cash) receivable upon such
Reorganization Event by a holder of the number of shares of Common Stock that
might have been received upon exercise of this Warrant immediately prior to such
Reorganization Event. Any such provision shall include provisions for
adjustments in respect of such shares of stock and other securities and property
that shall be as nearly equivalent as may be practicable to the adjustments
provided for in this Warrant. The provisions of this Section 4 shall apply to
successive Reorganization Events.

          5.   TENDER OFFERS. In case a Tender Offer on or after the Issuance
Date made by the Company or any Subsidiary for all or any portion of the Common
Stock shall expire and such Tender Offer (as amended upon the expiration
thereof) shall require the payment to stockholders (based on the acceptance (up
to any maximum specified in the terms of the Tender Offer) of Purchased Shares
(as defined below)) of an aggregate consideration having a fair market value (as
determined by the Board of Directors, whose determination shall be conclusive
and described in a Board Resolution) that combined together with (1) the
aggregate of the cash plus the fair market value (as determined by the Board of
Directors, whose determination shall be conclusive and described in a Board
Resolution), as of the expiration of such Tender Offer, of


                                       7
<PAGE>

consideration payable in respect of any other Tender Offers, by the Company or
any Subsidiary for all or any portion of the Common Stock expiring within the 12
months preceding the expiration of such Tender Offer and in respect of which no
adjustment pursuant to this Section 5 has been made and (2) the aggregate amount
of any distributions to all holders of the Company's Common Stock made
exclusively in cash within 12 months preceding the expiration of such Tender
Offer and in respect of which no adjustment pursuant to Section 3 has been made,
exceeds 10% of the product of the Current Fair Market Value as of the last time
(the "Expiration Time") tenders (including tenders by a stockholder of
securities and related documentation accepting an offer by the Company to
repurchase such stockholder's shares) could have been made pursuant to such
Tender Offer (as it may be amended) TIMES the number of shares of Common Stock
outstanding (including any tendered shares) at the Expiration Time, then, and in
each such case, immediately prior to the opening of business on the day after
the date of the Expiration Time:

          (a)  the Purchase Price shall be adjusted so that the same shall equal
     the price determined by multiplying the Purchase Price in effect
     immediately prior to close of business on the date of the Expiration Time
     by a fraction of which the numerator shall be the number of shares of
     Common Stock outstanding (including any tendered shares) at the Expiration
     Time multiplied by the Current Fair Market Value of the Common Stock on the
     Trading Day next succeeding the Expiration Time and the denominator shall
     be the sum of (x) the fair market value (determined as aforesaid) of the
     aggregate consideration payable to stockholders based on the acceptance (up
     to any maximum specified in the terms of the Tender Offer) of all shares
     validly tendered and not withdrawn as of the Expiration Time (the shares
     deemed so accepted, up to any such maximum, being referred to as the
     "Purchased Shares") and (y) the product of the number of shares of Common
     Stock outstanding (less any Purchased Shares) at the Expiration Time and
     the Current Fair Market Value of the Common Stock on the Trading Day next
     succeeding the Expiration Time; and

          (b)  the number of shares of Common Stock for which this Warrant may
     thereafter be exercised shall be adjusted at the time of such reduction (if
     any) in the Purchase Price to a number equal to the quotient obtained by
     dividing (x) the Aggregate Purchase Price in effect immediately prior to
     the close of business on the date of the Expiration Time BY (y) the
     Purchase Price in effect immediately after such reduction in the Purchase
     Price pursuant to clause (a) of this Section 5.

Such reduction (if any) in the Purchase Price and increase in the number of
shares of Common Stock for which the Warrant may thereafter be exercised shall
become effective immediately prior to the opening of business on the day
following the Expiration Time. In the event that the Company is obligated to
purchase shares pursuant to any such Tender Offer, but the Company is
permanently prevented by applicable law from effecting any such purchases or all
such purchases are rescinded, the Purchase Price shall again be adjusted to be
the Purchase Price which would then be in effect if such Tender Offer had not
been made. If the application of this Section 5 to any Tender Offer would result
in an increase in the Purchase Price, no adjustment shall be made for such
Tender Offer under this Section 5.


                                       8
<PAGE>

          6.   ADJUSTMENT FOR EXTRAORDINARY EVENTS. In the event that the
Company shall (i) issue additional shares of the Common Stock as a dividend or
other distribution on outstanding Common Stock, (ii) subdivide or reclassify its
outstanding shares of Common Stock, or (iii) combine its outstanding shares of
Common Stock into a smaller number of shares of Common Stock, then, in each such
event, the Purchase Price shall, simultaneously with the happening of such
event, be adjusted by multiplying the Purchase Price in effect immediately prior
to such event by a fraction, the numerator of which shall be the number of
shares of Common Stock outstanding immediately prior to such event and the
denominator of which shall be the number of shares of Common Stock outstanding
immediately after such event, and the product so obtained shall thereafter be
the Purchase Price then in effect. The Purchase Price, as so adjusted, shall be
readjusted in the same manner upon the happening of any successive event or
events described herein in this Section 6. The Holder shall thereafter, on the
exercise hereof as provided in Section 1, be entitled to receive that number of
shares of Common Stock determined by multiplying the number of shares of Common
Stock which would be issuable on such exercise immediately prior to such
issuance by a fraction of which (i) the numerator is the Purchase Price in
effect immediately prior to such issuance and (ii) the denominator is the
Purchase Price in effect on the date of such exercise.

          7.   ISSUANCE OF RIGHTS OR WARRANTS TO COMMON STOCKHOLDERS AT LESS
THAN CURRENT FAIR MARKET VALUE. In case the Company shall on or after the
Issuance Date issue rights or warrants to all holders of its outstanding shares
of Common Stock entitling them to subscribe for or purchase shares of Common
Stock at a price per share less than the Current Fair Market Value on the record
date fixed for the determination of stockholders entitled to receive such rights
or warrants, then

          (a)  the Purchase Price shall be adjusted so that the same shall equal
     the price determined by multiplying the Purchase Price in effect at the
     opening of business on the day after such record date by a fraction of
     which the numerator shall be the number of shares of Common Stock
     outstanding at the close of business on such record date plus the number of
     shares which the aggregate offering price of the total number of shares so
     offered would purchase at such Current Fair Market Value, and the
     denominator shall be the number of shares of Common Stock outstanding on
     the close of business on such record date plus the total number of
     additional shares of Common Stock so offered for subscription or purchase;
     and

          (b)  the number of shares of Common Stock which the Holder may
     thereafter purchase upon exercise of this Warrant at the opening of
     business on the day after such record date shall be increased to a number
     equal to the quotient obtained by dividing (x) the Aggregate Purchase Price
     in effect immediately prior to such adjustment in the Purchase Price
     pursuant to clause (a) of this Section 7 BY (y) the Purchase Price in
     effect immediately after such adjustment in the Purchase Price pursuant to
     clause (a) of this Section 7.

Such adjustment shall become effective immediately after the opening of business
on the day following the record date fixed for determination of stockholders
entitled to receive such rights or warrants. To the extent that shares of Common
Stock are not delivered pursuant to such rights or warrants, upon the expiration
or termination of such rights or warrants, the Purchase Price


                                       9
<PAGE>

shall be readjusted to the Purchase Price which would then be in effect had the
adjustments made upon the issuance of such rights or warrants been made on the
basis of delivery of only the number of shares of Common Stock actually
delivered and the number of shares of Common Stock for which this Warrant may
thereafter be exercised shall be readjusted (subject to proportionate adjustment
for any intervening exercises of this Warrant) to the number which would then be
in effect had the adjustments made upon the issuance of such rights or warrants
been made on the basis of delivery of only the number of shares of Common Stock
actually delivered. In the event that such rights or warrants are not so issued,
the Purchase Price shall again be adjusted to be the Purchase Price which would
then be in effect if such record date had not been fixed and the number of
shares of Common Stock for which this Warrant may thereafter be exercised shall
again be adjusted (subject to proportionate adjustment for any intervening
exercises of this Warrant) to be the number which would then be in effect if
such record date had not been fixed. In determining whether any rights or
warrants entitle the holder to subscribe for or purchase shares of Common Stock
at less than such Current Fair Market Value, and in determining the aggregate
offering price of such shares of Common Stock, there shall be taken into account
any consideration received for such rights or warrants, the value of such
consideration, if other than cash, to be determined by the Board of Directors.

          8.   ISSUANCE AT LESS THAN CURRENT FAIR MARKET VALUE.

          (a)  In case at any time on or after the Issuance Date the Company
shall issue shares of its Common Stock or Common Stock Equivalents
(collectively, the "Newly Issued Shares"), other than an issuance pro rata to
all holders of its outstanding Common Stock, at a price below the Current Fair
Market Value of the Common Stock at the time of such issuance, then following
such issuance of Newly Issued Shares the Purchase Price shall be reduced as
provided in clause (b) of this Section 8 and the number of shares of Common
Stock which may be issued upon exercise of this Warrant shall be increased as
provided in clause (c) of this Section 8.

          (b)  The reduction in the Purchase Price following any such adjustment
shall be determined by multiplying the Purchase Price immediately prior to such
adjustment by a fraction, of which the numerator shall be the sum of (1) the
number of shares of Common Stock outstanding immediately prior to the issuance
of the Newly Issued Shares (calculated on a fully-diluted basis assuming the
exercise or conversion of all options, warrants, purchase rights or convertible
securities which are exercisable or convertible at the time of the issuance of
the Newly Issued Shares) PLUS (2) the number of shares of Common Stock which the
aggregate consideration, if any, received by the Company for the number of Newly
Issued Shares would purchase at a price equal to the Current Fair Market Value
of the Common Stock at the time of such issuance, and the denominator shall be
the sum of (X) the number of shares of Common Stock outstanding immediately
prior to the issuance of the Newly Issued Shares (calculated on a fully-diluted
basis assuming the exercise or conversion of all options, warrants, purchase
rights or convertible securities which are exercisable or convertible at the
time of the issuance of the Newly Issued Shares) PLUS (Y) the number of Newly
Issued Shares. The adjustment provided for in this Section 8(b) may be expressed
as the following mathematical formula:

                (O + (C/FMV))
          NPP = -------------  x PP
                   (O + N)



                                       10
<PAGE>

     where,

           C        =        aggregate consideration received by the Company for
                             the Newly Issued Shares

           N        =        number of Newly Issued Shares

           O        =        number of shares of Common Stock outstanding (on a
                             fully diluted basis, as described above)
                             immediately prior to the issuance of the Newly
                             Issued Shares

           FMV      =        Current Fair Market Value of the Common Stock at
                             the time of issuance of the Newly Issued Shares

           PP       =        Purchase Price immediately prior to the issuance of
                             the Newly Issued Shares

           NPP      =        Purchase Price immediately after the issuance of
                             the Newly Issued Shares

          (c)  If the Purchase Price is reduced in connection with the issuance
of Newly Issued Shares as provided in Section 8(b), then the number of shares of
Common Stock for which this Warrant may thereafter be exercised shall be
increased at the time of such reduction in the Purchase Price to a number equal
to the quotient obtained by dividing (x) the Aggregate Purchase Price in effect
immediately prior to such issuance of Newly Issued Shares by (y) the Purchase
Price in effect immediately after such issuance of Newly Issued Shares after
giving effect to such reduction in the Purchase Price pursuant to Section 8(b).

          (d)  Notwithstanding the foregoing, no adjustment shall be made under
this Section 8 by reason of:

          (1)  the issuance by the Company of shares of Common Stock pro rata to
all holders of the Common Stock so long as (i) any adjustment required by
Section 6 is made and (ii) the Company shall have given notice thereof to the
Holder pursuant to Section 14;

          (2)  the issuance by the Company of Newly Issued Shares in an offering
for cash for the account of the Company that is underwritten on a firm
commitment basis and (i) is registered under the 1933 Act, or (ii) is sold in an
offering to "qualified institutional buyers" as defined in, and in a transaction
under, Rule 144A under the 1933 Act;

          (3)  The issuance by the Company for cash of Newly Issued Shares in
connection with a strategic alliance, collaboration, joint venture, partnership
or similar arrangement of the Company with another Person which strategic
alliance, collaboration, joint venture, partnership or similar arrangement
relates to the Company's business as conducted immediately prior thereto and
which Person is engaged in a business similar or related to the business of the
Company so long as (x) the price per Newly Issued Share is not less than 85
percent of the Current Fair Market Value of the Common Stock on the date of
issuance of such Newly Issued Shares and (y) the consideration other than cash
which the Company receives in


                                       11
<PAGE>

connection with such strategic alliance, collaboration, joint venture,
partnership or similar arrangement has a value, as determined by the Board of
Directors in its reasonable judgment and set forth in a Board Resolution, at
least equal to the amount by which (i) the product of the number of Newly Issued
Shares so issued TIMES the Current Fair Market Value of the Common Stock on the
date such Newly Issued Shares are issued exceeds (ii) the aggregate cash
consideration received by the Company for such Newly Issued Shares at the time
of issuance thereof;

          (4)  the issuance by the Company of Common Stock upon exercise of this
Warrant or the Other Warrants in accordance with the terms hereof and thereof;

          (5)  the issuance by the Company of shares of Common Stock upon
conversion of or as dividends on the Series A Preferred Stock in accordance with
the terms thereof;

          (6)  the issuance by the Company of Common Stock upon conversion of or
as dividends on the Series A Preferred Stock in accordance with the terms
thereof; the issuance by the Company of shares of Common Stock to any employee,
officer or director of, or consultant to, the corporation pursuant to any stock
option plans or agreements approved by the Company's board of directors; or

          (7)  the issuance by the Company of shares of Common Stock or other
securities to any bank, equipment lessor or other similar financial institution
in connection with commercial credit arrangements, equipment financing or
similar transactions approved by the Company's board of directors.

          9.   CANCELLATION OF WARRANT.

          (a)  Subject to the satisfaction of the conditions set forth in
Sections 9(b) and 9(c) hereof, if, on or before December 5, 2001, the Average
Market Price of one share of Common Stock (or unit of other securities
deliverable hereunder) receivable upon exercise of this Warrant shall exceed
the Target Price over a twenty Trading Day Period this Warrant shall be
cancelled. The Class B Warrants will be cancelled effective as of 5:00 p.m.
on the Trading Day immediately following such period, and the Company will
give notice of such cancellation to the Holder. Upon receipt of such notice,
the Holder will promptly deliver this Warrant to the Company for
cancellation. Notwithstanding the foregoing, the Company may, in its sole
discretion, at any time prior to the cancellation of the Warrants pursuant to
this Section 9, cause all, but not less than all, of the Class B Warrants to
not be cancelled.

          (b)  On the date notice of cancellation is given, the Company shall be
in compliance in all material respects with its obligations to the Holder
(including, without limitation, its obligations under the Transaction
Documents).

          (c)  On the date notice of cancellation is given, the Registration
Statement shall be effective and available for use by the selling stockholders
named therein and shall reasonably be expected to remain effective and available
for such use for the 135 days following the Cancellation Date.


                                       12
<PAGE>

          10.  TAX ADJUSTMENTS. The Company may make such reductions in the
Purchase Price, in addition to those required by Sections 3, 4, 5, 6, 7 and 8 as
the Board of Directors considers to be advisable to avoid or diminish any income
tax to holders of Common Stock or rights to purchase Common Stock resulting from
any dividend or distribution of stock (or rights to acquire stock) or from any
event treated as such for income tax purposes.

          11.  MINIMUM ADJUSTMENT.

          (a)  No adjustment in the Purchase Price (and no related adjustment in
the number of shares of Common Stock which may thereafter be purchased upon
exercise of this Warrant) shall be required unless such adjustment would require
an increase or decrease of at least 1% in the Purchase Price; PROVIDED, HOWEVER,
that any adjustments which by reason of this Section 11 are not required to be
made shall be carried forward and taken into account in any subsequent
adjustment. All such calculations under this Warrant shall be made by the
Company and shall be made to the nearest cent or to the nearest one hundredth of
a share, as the case may be.

          (b)  No adjustment need be made for a change in the par value of the
Common Stock or from par value to no par value or from no par value to par
value.

          12.  NOTICE OF ADJUSTMENTS. Whenever the Purchase Price is adjusted as
herein provided, the Company shall promptly, but in no event later than five
business days thereafter, give a notice to the Holder setting forth the Purchase
Price and number of shares of Common Stock which may be purchased upon exercise
of this Warrant after such adjustment and setting forth a brief statement of the
facts requiring such adjustment. Failure to deliver such notice shall not affect
the legality or validity of any such adjustment.

          13.  FURTHER ASSURANCES. The Company will take all action that may be
necessary or appropriate in order that the Company may validly and legally issue
fully paid and nonassessable shares of stock, free from all taxes, liens and
charges with respect to the issue thereof, on the exercise of all or any portion
of this Warrant from time to time outstanding.

          14.  NOTICE TO HOLDER PRIOR TO CERTAIN ACTIONS. In case on or after
the Issuance Date:

          (a)  the Company shall declare a dividend (or any other
     distribution) on its Common Stock (other than in cash out of retained
     earnings); or

          (b)  the Company shall authorize the granting to the holders of its
     Common Stock of rights or warrants to subscribe for or purchase any
     share of any class or any other rights or warrants; or

          (c)  the Board of Directors shall authorize any reclassification of
     the Common Stock (other than a subdivision or combination of its
     outstanding Common Stock, or a change in par value, or from par value to
     no par value, or from no par value to par value), or any consolidation
     or merger or other business combination transaction to which the Company
     is a party and for which approval of any stockholders of the Company is
     required, or the sale or transfer of all or substantially all of the
     assets of the Company; or


                                       13
<PAGE>

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

the Company shall give the Holder, as promptly as possible but in any event at
least ten Trading Days prior to the applicable date hereinafter specified, a
notice stating (x) the date on which a record is to be taken for the purpose of
such dividend, distribution or rights or warrants, or, if a record is not to be
taken, the date as of which the holders of Common Stock of record to be entitled
to such dividend, distribution or rights are to be determined, or (y) the date
on which such reclassification, consolidation, merger, other business
combination transaction, sale, transfer, dissolution, liquidation or winding-up
is expected to become effective or occur, and the date as of which it is
expected that holders of Common Stock of record who shall be entitled to
exchange their Common Stock for securities or other property deliverable upon
such reclassification, consolidation, merger, other business combination
transaction, sale, transfer, dissolution, liquidation or winding-up shall be
determined. Such notice shall not include any information which would be
material non-public information for purposes of the 1934 Act. Failure to give
such notice, or any defect therein, shall not affect the legality or validity of
such dividend, distribution, reclassification, consolidation, merger, sale,
transfer, dissolution, liquidation or winding-up. In the case of any such action
of which the Company gives such notice to the Holder or is required to give such
notice to the Holder, the Holder shall be entitled to give a subscription form
to exercise this Warrant in whole or in part that is contingent on the
completion of such action.

          15.  RESERVATION OF STOCK, ETC., ISSUABLE ON EXERCISE OF WARRANTS. The
Company will at all times reserve and keep available out of its authorized but
unissued shares of capital stock, solely for issuance and delivery on the
exercise of this Warrant, a sufficient number of shares of Common Stock (or
Other Securities) to effect the full exercise of this Warrant and the exercise,
conversion or exchange of any other warrant or security of the Company
exercisable for, convertible into, exchangeable for or otherwise entitling the
holder to acquire shares of Common Stock (or Other Securities), and if at any
time the number of authorized but unissued shares of Common Stock (or Other
Securities) shall not be sufficient to effect such exercise, conversion or
exchange, the Company shall take such action as may be necessary to increase its
authorized but unissued shares of Common Stock (or Other Securities) to such
number as shall be sufficient for such purposes.

          16.  TRANSFER OF WARRANT. This Warrant shall inure to the benefit of
the successors to and assigns of the Holder. This Warrant and all rights
hereunder, in whole or in part, are registrable at the office or agency of the
Company referred to below by the Holder in Person or by his duly authorized
attorney, upon surrender of this Warrant properly endorsed accompanied by the
assignment form in the form annexed hereto duly executed by the transferring
Holder.


                                       14
<PAGE>

          17.  REGISTER OF WARRANTS. The Company shall maintain, at the
principal office of the Company (or such other office as it may designate by
notice to the Holder), a register in which the Company shall record the name and
address of the Person in whose name this Warrant has been issued, as well as the
name and address of each successor and prior owner of such Warrant. The Company
shall be entitled to treat the Person in whose name this Warrant is so
registered as the sole and absolute owner of this Warrant for all purposes.

          18.  EXCHANGE OF WARRANT. This Warrant is exchangeable, upon the
surrender hereof by the Holder at the office or agency of the Company referred
to in Section 17, for one or more new Warrants of like tenor representing in the
aggregate the right to subscribe for and purchase the number of shares of Common
Stock which may be subscribed for and purchased hereunder, each of such new
Warrants to represent the right to subscribe for and purchase such number of
shares as shall be designated by the Holder at the time of such surrender.

          19.  REPLACEMENT OF WARRANT. On receipt by the Company of evidence
reasonably satisfactory to it of the ownership of and the loss, theft,
destruction or mutilation of this Warrant and (a) in the case of loss, theft or
destruction, of indemnity from the Holder reasonably satisfactory in form to the
Company (and without the requirement to post any bond or other security), or (b)
in the case of mutilation, upon surrender and cancellation of this Warrant, the
Company will execute and deliver to the Holder a new Warrant of like tenor
without charge to the Holder.

          20.  WARRANT AGENT. The Company may, by written notice to the Holder,
appoint the transfer agent and registrar for the Common Stock as the Company's
agent for the purpose of issuing Common Stock (or Other Securities) on the
exercise of this Warrant pursuant to Section 1, and the Company may, by written
notice to the Holder, appoint an agent having an office in the United States of
America for the purpose of exchanging this Warrant pursuant to Section 18, and
replacing this Warrant pursuant to Section 19, or any of the foregoing, and
thereafter any such exchange or replacement, as the case may be, shall be made
at such office by such agent.

          21.  REMEDIES. The Company stipulates that the remedies at law of the
Holder in the event of any default or threatened default by the Company in the
performance of or compliance with any of the terms of this Warrant are not and
will not be adequate, and that such terms may be specifically enforced by a
decree for the specific performance of any agreement contained herein or by an
injunction against a violation of any of the terms hereof or otherwise.

          22.  NO RIGHTS OR LIABILITIES AS A STOCKHOLDER. This Warrant shall not
entitle the Holder to any voting rights or other rights as a stockholder of the
Company. Nothing contained in this Warrant shall be construed as conferring upon
Holder hereof the right to vote or to consent or to receive notice as a
stockholder of the Company on any matters or with respect to any rights
whatsoever as a stockholder of the Company. No dividends or interest shall be
payable or accrued in respect of this Warrant or the interest represented hereby
or the Common Stock (or Other Securities) purchasable hereunder until, and only
to the extent that, this Warrant shall have been exercised in accordance with
its terms.


                                       15
<PAGE>

          23.  NOTICES, ETC. All notices and other communications from the
Company to the Holder shall be mailed by first class certified mail, postage
prepaid, at such address as may have been furnished to the Company in writing by
the Holder or at the address shown for the Holder on the register of Warrants
referred to in Section 17.

          24.  TRANSFER RESTRICTIONS. This Warrant has not been and is not being
registered under the provisions of the 1933 Act or any state securities laws and
this Warrant may not be transferred unless (1) the transferee is an "accredited
investor" (as defined in Regulation D under the 1933 Act) or a QIB in a transfer
that meets the requirements of Rule 144A and (2) the Holder shall have delivered
to the Company an opinion of counsel, reasonably satisfactory in form, scope and
substance to the Company, to the effect that this Warrant may be sold or
transferred without registration under the 1933 Act. Prior to any such transfer,
such transferee shall have represented in writing to the Company that such
transferee has requested and received from the Company all information relating
to the business, properties, operations, condition (financial or other), results
of operations or prospects of the Company deemed relevant by such transferee;
that such transferee has been afforded the opportunity to ask questions of the
Company concerning the foregoing and has had the opportunity to obtain and
review the Registration Statement (as defined in the Subscription Agreement) and
the prospectus included therein, each as amended or supplemented to the date of
transfer to such transferee, and the reports and other information concerning
the Company which at the time of such transfer have been filed by the Company
with the SEC pursuant to the 1934 Act and which are incorporated by reference in
such prospectus as of the date of such transfer. If such transfer is intended to
assign the rights and obligations under Sections 5(a), 5(b) and 8 of the
Subscription Agreement, such transfer shall otherwise be made in compliance with
Section 11(j) of the Subscription Agreement.

          25.  RULE 144A INFORMATION REQUIREMENT. Within the period prior to the
expiration of the holding period applicable to sales hereof under Rule 144(k)
under the 1933 Act (or any successor provision), the Company covenants and
agrees that it shall, during any period in which it is not subject to Section 14
or 16(d) under the 1934 Act, make available to the Holder and the holder of any
shares of Common Stock issued upon exercise of this Warrant which continue to be
Restricted Securities in connection with any sale thereof and any prospective
purchaser of this Warrant from the Holder, the information required pursuant to
Rule 144A(d)(4) under the 1933 Act upon the request of the Holder and it will
take such further action as the Holder may reasonably request, all to the extent
required from time to time to enable the Holder to sell this Warrant without
registration under the 1933 Act within the limitation of the exemption provided
by Rule 144A, as Rule 144A may be amended from time to time. Upon the request of
the Holder, the Company will deliver to the Holder a written statement as to
whether it has complied with such requirements.

          26.  LEGEND. Unless theretofore registered for resale under the 1933
Act, each certificate for shares issued upon exercise of this Warrant shall bear
the following legend:

     The securities represented by this certificate have not been registered
     under the Securities Act of 1933, as amended. The securities have been
     acquired for investment and may not be resold, transferred or assigned in
     the absence of an effective registration statement for


                                       16
<PAGE>

     the securities under the Securities Act of 1933, as amended, or an opinion
     of counsel that registration is not required under said Act.

          27.  AMENDMENT; WAIVER. This Warrant and any terms 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.

          28.  MISCELLANEOUS. This Warrant shall be construed and enforced in
accordance with and governed by the internal laws of the State of New York. The
headings, captions and footers in this Warrant are for purposes of reference
only, and shall not limit or otherwise affect any of the terms hereof. The
invalidity or unenforceability of any provision hereof shall in no way affect
the validity or enforceability of any other provision.



                  [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]



                                       17
<PAGE>


     IN WITNESS WHEREOF, the Company has caused this Warrant to be executed on
its behalf by one of its officers thereunto duly authorized.

Dated: December __, 2000                VALENTIS, INC.



                                        By:____________________________________
                                           Name:
                                           Title:










                                       18
<PAGE>


                                   ASSIGNMENT

         FOR VALUE RECEIVED, _________________________ hereby sell(s),
assign(s) and transfer(s) unto _________________________ (Please insert
social security or other Taxpayer Identification Number of assignee:
______________________________) the attached original, executed Warrant to
purchase ____________ shares of Common Stock of Valentis, Inc., a Delaware
corporation (the "Company"), and hereby irrevocably constitutes and appoints
_________________________ attorney to transfer the Warrant on the books of
the Company, with full power of substitution in the premises.

         In connection with any transfer of the Warrant within the period prior
to the expiration of the holding period applicable to sales thereof under Rule
144(k) under the 1933 Act (or any successor provision) (other than any transfer
pursuant to a registration statement that has been declared effective under the
1933 Act), the undersigned confirms that such Warrant is being transferred:

         [ ]   To the Company or a subsidiary thereof; or

         [ ]   To a QIB pursuant to and in compliance with Rule 144A; or

         [ ]   To an "accredited investor" (as defined in Regulation D under the
1933 Act) pursuant to and in compliance with the 1933 Act; or

         [ ]   Pursuant to and in compliance with Rule 144 under the 1933 Act;

and unless the box below is checked, the undersigned confirms that, to the
knowledge of the undersigned, such Warrant is not being transferred to an
"affiliate" (as defined in Rule 144 under the 1933 Act) of the Company.

         [ ]   The transferee is an affiliate of the Company.

         Capitalized terms used in this Assignment and not defined in this
Assignment shall have the respective meanings provided in the Warrant.

Dated:________________            NAME:_______________________________________



                                  Signature(s)





                                       19
<PAGE>


                                                                       EXHIBIT 1

                              FORM OF SUBSCRIPTION

                                 VALENTIS, INC.

                   (To be signed only on exercise of Warrant)

TO:       Valentis, Inc.
          863A Mitten Road
          Burlingame, California  94010

Attention:

          1.   The undersigned Holder of the attached original, executed Warrant
hereby elects to exercise its purchase right under such Warrant with respect to
______________ shares (the "Exercise Shares") of Common Stock, as defined in the
Warrant, of Valentis, Inc., a Delaware corporation (the "Company").

          2.   The undersigned Holder (check one):

     / /  (a)  elects to pay the aggregate purchase price for such shares of
               Common Stock (i) in lawful money of the United States or by the
               enclosed certified or official bank check payable in United
               States dollars to the order of the Company in the amount of
               $___________, or (ii) by wire transfer of United States funds to
               the account of the Company in the amount of $____________, which
               transfer has been made before or simultaneously with the delivery
               of this Form of Subscription pursuant to the instructions of the
               Company;

          or

     / /  (b)  elects to receive shares of Common Stock having a value equal to
               the value of the Warrant calculated in accordance with Section
               1.2 of the Warrant.

          3.   Please issue a stock certificate or certificates representing the
appropriate number of shares of Common Stock in the name of the undersigned or
in such other names as is specified below:

         Name: ____________________

         Address: __________________________________________

                  __________________________________________

Dated:




                                       20
<PAGE>

                                             ___________________________________
                                             (Signature,

                                             ___________________________________

                                             ___________________________________
                                                   (Address)


Note: This Subscription must be signed exactly as the name appears on the
Warrant, and to the extent that Holder requests that the certificates
representing the Exercise Shares be issued to a name other than that of the
Holder or via the Deposit Withdrawal Agent Commission system, the Holder's
signature must be guaranteed by an eligible guarantor institution such as a
bank, stockbroker, savings and loan association or credit union with
membership in an approved medallion signature guarantee program.



                                       21