EXHIBIT 4.5

THESE SECURITIES HAVE NOT BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933 OR
ANY STATE LAWS. THEY MAY NOT BE SOLD, OFFERED FOR SALE, PLEDGED OR HYPOTHECATED
IN THE ABSENCE OF A REGISTRATION STATEMENT IN EFFECT WITH RESPECT TO THE
SECURITIES UNDER SUCH ACT OR AN OPINION OF COUNSEL SATISFACTORY TO THE COMPANY
THAT SUCH REGISTRATION IS NOT REQUIRED OR UNLESS SOLD PURSUANT TO RULE 144 OF
SUCH ACT.


                              WARRANT TO PURCHASE
                         200,000 SHARES OF COMMON STOCK

                      SENSUS DRUG DEVELOPMENT CORPORATION
             (INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE)

     THIS CERTIFIES THAT, for value received, R. Steven Hicks (the
"Warrantholder") is entitled to purchase, on the terms hereof, Two Hundred
Thousand (200,000) shares of Common Stock (the "Common Stock") of Sensus Drug
Development Corporation, a Delaware corporation (the "Company"), at a purchase
price as set forth herein.

1.   EXERCISE OF WARRANT

     The terms and conditions upon which this Warrant may be exercised, and the
Common Stock covered hereby (the "Warrant Stock") may be purchased, are as
follows:

     1.1  EXERCISE.  This Warrant may be exercised in whole or in part at any
time on or after the date hereof, but in no case may this Warrant be exercised
later than 5:00 p.m., Austin, Texas time on September ___, 2003 (the
"Termination Date"), after which time this Warrant shall terminate and shall be
void of no further force or effect.

     1.2  EXERCISE PRICE.  The purchase price for the shares of Common Stock to
be issued upon exercise of this Warrant shall be $3.50 per share, subject to
adjustment as set forth herein (the "Exercise Price").

     1.3  METHOD OF EXERCISE.  The exercise of the purchase rights evidenced by
this Warrant shall be effected by (a) the surrender of this Warrant, together
with a duly executed copy of the form of Subscription attached hereto, to the
Company at its principal office and (b) the delivery of the Exercise Price by
check or bank draft payable to the Company's order for the number of shares for
which the purchase rights hereunder are being exercised or any other form of
consideration approved by the Company's Board of Directors.

     1.4  ISSUANCE OF SHARES.  In the event that the purchase rights evidenced
by this Warrant are exercised in whole or in part, a certificate or certificates
for the purchased shares shall be issued to the Warrantholder as soon as
practicable.  In the event the purchase rights evidenced by this Warrant are
exercised in part, the Company will also issue to the Warrantholder a new
warrant representing the unexercised purchase rights.

                                      1.

 
2.   ADJUSTMENT OF STOCK PURCHASE PRICE AND NUMBER OF SHARES

     The Exercise 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 2.  Upon each adjustment
of the Exercise Price, the Holder of this Warrant shall thereafter be entitled
to purchase, at the Exercise Price resulting from such adjustment, the number of
shares obtained by multiplying the Exercise 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 Exercise Price
resulting from such adjustment.

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

     2.2  DIVIDENDS.  If at any time or from time to time the Holders of Common
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) Any shares of stock or other securities which are at any time
directly or indirectly convertible into or exchangeable for Common Stock, or any
rights or options to subscribe for, purchase or otherwise acquire any of the
foregoing by way of dividend or other distribution,

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

          (C) Common Stock 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 Common Stock
issued as a stock split or adjustments in respect of which shall be covered by
the terms of Section 2.1 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 Common Stock receivable thereupon, and without payment
of any additional consideration therefor, the amount of stock and other
securities and property (including cash in the cases referred to in clause (b)
above and this clause (c)), which such Holder would hold on the date of such
exercise had be been the holder of record of such Common Stock as of the date on
which holders of Common Stock received or became entitled to receive such shares
or all other additional stock and other securities and property.

     2.3  REORGANIZATION, RECLASSIFICATION, CONSOLIDATION, MERGER OR SALE.  If
any recapitalization, reclassification or 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 or other
transaction shall be effected in such a way that holders of Common Stock shall
be entitled to receive stock, securities, or other assets or property (an
"Organic Change"), then, as a condition of such Organic Change, lawful and
adequate provisions

                                      2.

 
shall be made by the Company whereby the Holder hereof shall thereafter have the
right to purchase and receive (in lieu of the shares of the Common Stock of the
Company immediately theretofore purchasable and receivable upon the exercise of
the rights represented hereby) such shares of stock, securities or other assets
or property as may be issued or payable with respect to or in exchange for a
number of outstanding shares of such Common Stock equal to the number of shares
of such stock immediately theretofore purchasable and receivable upon the
exercise of the rights represented hereby; provided, however, that in the event
the value of the stock, securities or other assets or property (determined m
good faith by the Board of Directors of the Company) issuable or payable with
respect to one share of the Common Stock of the Company immediately theretofore
purchasable and receivable upon the exercise of the rights represented hereby is
in excess of the Exercise Price hereof effective at the time of a merger and
securities received in such reorganization, if any, are publicly traded, then
this Warrant shall expire unless exercised prior to such Organic Change. In the
event of -any Organic Change, appropriate provision shall be made by the Company
with respect to the rights and interests of the Holder of this Warrant to the
end that the provisions hereof (including, without limitation, provisions for
adjustments of the Exercise Price and of the number of shares purchasable and
receivable upon the exercise of this Warrant) shall thereafter be applicable, 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 reasonably
satisfactory in form and substance to the Holders of a majority of the warrants
to purchase Common Stock then outstanding, 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.

     2.4  CERTAIN EVENTS.  If any change in the outstanding Common Stock of the
Company or any other event occurs as to which the other provisions of this
Section 2 are not strictly applicable or if strictly applicable would not fairly
protect the purchase rights of the Holder of the Warrant in accordance with 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 Exercise
Price or the application of such provisions, 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 Exercise 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.

     2.5  NOTICES OF CHANGE.

          (A) Immediately upon any adjustment in the number or class of shares
subject to this Warrant and of the Exercise Price, the Company shall give
written notice thereof to the Holder, setting forth in reasonable detail and
certifying the calculation of such adjustment.

          (B) The Company shall give written notice to the Holder at least ten
(10) business days prior to the date on which the Company closes its books or
takes a record for determining rights to receive any dividends or distributions.

                                      3.

 
          (C) The Company shall also give written notice to the Holder at least
thirty (30) business days prior to the date on which an Organic Change shall
take place.

3.   FRACTIONAL SHARES.

     No fractional shares shall be issued in connection with any exercise of
this Warrant.  In lieu of the issuance of such fractional share, the Company
shall make a cash payment equal to the then fair market value of such fractional
share as determined by the Company's Board of Directors.

4.   RESERVATION OF COMMON STOCK.

     The Company shall at all times reserve and keep available out of its
authorized but unissued shares of Common Stock, solely for the purpose of
effecting the exercise of this Warrant, such number of its shares of Common
Stock as shall from time to time be sufficient to effect the exercise of this
Warrant; and if at any time the number of authorized but unissued shares of
Common Stock shall not be sufficient to effect the exercise of the entire
Warrant, in addition to such other remedies as shall be available to the holder
of this Warrant, the Company will use its reasonable best efforts to take such
corporate action as may, in the opinion of its counsel, be necessary to increase
its authorized but unissued shares of Common Stock to such number of shares as
shall be sufficient for such purposes.

5.   PRIVILEGE OF STOCK OWNERSHIP.

     Prior to the exercise of this Warrant, the Warrantholder shall not be
entitled, by virtue of holding this Warrant, to any rights of a stockholder of
the Company, including (without limitation) the right to vote, receive dividends
or other distributions, exercise preemptive rights or be notified of stockholder
meetings, and such holder shall not be entitled to any notice or other
communication concerning the business or affairs of the Company, except as
required by law.

6.   LIMITATION OF LIABILITY.

     No provision hereof, in the absence of affirmative action by the holder
hereof to purchase the securities issuable under this Warrant, 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 purchase price or as a stockholder
of the Company, whether such liability is asserted by the Company or by
creditors of the Company.

7.   TRANSFERS AND EXCHANGES.

     7.1  Subject to compliance with applicable securities laws, this Warrant
and all rights hereunder are transferable in whole or in part by the
Warrantholder.  The transfer shall be recorded on the books of the Company upon
the surrender of this Warrant, properly endorsed, to the Company at its
principal offices and the payment to the Company of all transfer taxes and other
governmental charges imposed on such transfer.  In the event of a partial
transfer, the Company shall issue to the several holders one or more appropriate
new warrants.


                                      4.

 
     7.2  Each holder agrees that this Warrant when endorsed in blank shall be
negotiable and that when so endorsed the holder may be treated by the Company
and all other persons dealing with this Warrant as the absolute owner for all
purposes and as the person entitled to exercise the purchase rights evidenced
hereby; provided, however, that until such time as the transfer is recorded on
the books of the Company, the Company may treat the registered holder of this
Warrant as the absolute owner.

     7.3  All new warrants issued in connection with transfers, exchanges or
partial exercises shall be identical in form and provision to this Warrant
except as to the number of shares.

8.   PAYMENT OF TAXES.

     The Company shall pay all expenses in connection with, and all taxes and
other governmental charges (other than any thereof on, based on or measured by,
the net income of the holder thereof) that may be imposed in respect of, the
issue or delivery of the securities issuable under this Warrant.  The Company
shall not be required, however, to pay any tax or other charge imposed in
connection with any transfer involved in the issue of any certificate for shares
of the securities issuable under this Warrant in any name other than that of the
Warrantholder, and in such case, the Company shall not be required to issue or
deliver any stock certificate until such tax or other charge has been paid or it
has been established to the Company's satisfaction that no such tax or other
charge is due.

9.   NO IMPAIRMENT OF RIGHTS.

     The Company hereby agrees that it will not, through the amendment of its
Certificate of Incorporation or otherwise, avoid or seek to avoid the observance
or performance of any of the terms of this Warrant, but will at all times in
good faith assist in the carrying out of all such terms and in the taking of all
such actions as may be necessary or appropriate in order to protect the rights
of the Warrantholder against impairment.

10.  SUCCESSORS AND ASSIGNS.

     The terms and provisions of this Warrant shall be binding upon the Company
and the Warrantholder and their respective successors and assigns.

11.  LOSS, THEFT, DESTRUCTION OR MUTILATION OF WARRANT.

     Upon receipt by the Company of evidence reasonably satisfactory to it of
the loss, theft, destruction or mutilation of this Warrant, and in case of loss,
theft or destruction, upon receipt of an indemnity or security reasonably
satisfactory to the Company, and upon reimbursement to the Company of all
reasonable expenses incidental thereto, and upon surrender and cancellation of
this Warrant, if mutilated, the Company will make and deliver a new warrant of
like tenor and dated as of such cancellation, in lieu of this Warrant.


                                      5.

 
12.  RESTRICTED SECURITIES.

     The Warrantholder understands that this Warrant and the securities
purchasable hereunder constitute "restricted securities" under the federal
securities laws inasmuch as they are, or will be, acquired from the Company in
transactions not involving a public offering and accordingly may not, under such
laws and applicable regulations, be resold or transferred without registration
under the Securities Act of 1933 or an applicable exemption from registration.
In this connection, the Warrantholder acknowledges that Rule 144 of the
Securities and Exchange Commission is not now, and may not in the future be,
available for resales of this Warrant and the securities purchased hereunder.

13.  SATURDAYS, SUNDAYS, HOLIDAYS.

     If the last or appointed day for the taking of any action or the expiration
of any right required or granted hereto shall be a Saturday or Sunday or shall
be a legal holiday, then such action may be taken or such right may be
exercised, except as to the purchase price, on the next succeeding day not a
legal holiday.


                                           SENSUS DRUG DEVELOPMENT CORPORATION
 
 
 
                                      By:  /s/ John A. Scarlett
                                           -------------------------------------
                                           John A. Scarlett, M.D.
                                           President and Chief Executive Officer


Dated: September 4, 1998


                                      6.

 
                                  SUBSCRIPTION

                                        


Sensus Drug Development Corporation


Ladies and Gentlemen:

     The undersigned hereby elects to purchase, pursuant to the provisions of
the Warrant dated September ___, 1998 held by the undersigned, ________ shares
of the Common Stock of SENSUS DRUG DEVELOPMENT CORPORATION, a Delaware
corporation.

     Payment of the per share purchase price required under such Warrant
accompanies this Subscription.

     The undersigned hereby represents and warrants that the undersigned is
acquiring such stock for its own account and not for resale or with a view to
distribution of any part thereof and accepts such shares subject to the terms
and conditions of the Warrant:

Dated: _________, 19 ___

 
                              ___________________________
                              Print Name of Warrantholder

                              By:________________________

                              Address:___________________

                              ___________________________


                                      7.