<PAGE>

                                                                  EXHIBIT 10.47


                                       

                                    SUBLEASE


                         5828 PACIFIC CENTER BOULEVARD 
                                  (SUITE 200)

                             SAN DIEGO, CALIFORNIA






                           MOLECULAR BIOSYSTEMS, INC.
                             a Delaware corporation

                                 as Sublessor 

                                      and

                           DURA PHARMACEUTICALS, INC.
                             a Delaware corporation

                                  as Sublessee






                                October 1, 1997


<PAGE>

                           BASIC SUBLEASE INFORMATION


DEFINED TERMS


Building:                5828 Pacific Center Boulevard 
                         San Diego, California  92121

Effective Date:          October 1, 1997

Commencement Date:       October 1, 1997

Rent Commencement
Date:                    October 1, 1997 

Master Landlord:         Radnor/Collins/Sorrento Partnership, 
                         a California general partnership 

Master Landlord's
Address for              5963 La Place Court, Suite 109
Rent and Notice:         Carlsbad, California  92008

                         with a copy to:

                         RADNOR PACIFIC CORPORATE 
                         CENTER CORPORATION
                         9255 Town Center Drive, Suite 100
                         San Diego, California  92121
                    
Master Lease:            That certain Pacificpoint Triple Net Lease by and 
                         between Master Landlord and Sublessor, dated May 18, 
                         1995, a true and complete copy of which is attached 
                         hereto and incorporated herein as EXHIBIT A.

Master Premises:         The Building, consisting of approximately 54,712 square
                         feet.

Premises:                Improved real property as more particularly described 
                         in the Master Lease, consisting of a portion of the 
                         Master Premises, containing approximately 32,827 
                         rentable square feet as depicted on EXHIBIT B 
                         attached hereto and incorporated herein, and a non-
                         exclusive right to utilize all of Sublessor's 
                         leasehold interest in the Common Areas of the Project 
                         (as defined in Section 49 of the Master Lease),
                         including, without limitation, Sublessor's parking 
                         rights (on a proportionate basis) and rights to any 
                         appurtenant easements under the Master Lease.  The 
                         Premises shall include Sublessee's right to utilize 
                         the common areas within the Building ("Building 
                         Common Areas") as depicted on EXHIBIT B-1.


                                       i

<PAGE>


Monthly Base Rent:       SUBLEASE MONTHS    RENT PER SQ.FT.   MONTHLY NNN RENT
                                1-9             $ .94             $30,858
                              10-12               .98             $32,170

Security            
Deposit:                 None

Sublessee:               Dura Pharmaceuticals, Inc., a Delaware corporation 

Sublessee's              5880 Pacific Center Boulevard 
Address for Notice:      San Diego, California  92121
                         Attn:  Mitch Woodbury

Sublessee's              
Proportionate Share:     Sixty Percent (60%) of Building Operating Expenses
                         and Taxes as defined in Paragraph 3.2 of this Sublease.

Sublessor:               Molecular Biosystems, Inc. 
                         a Delaware corporation

Sublessor's              10030 Barnes Canyon Road 
Address for              San Diego, California 92121
Notice:                  Attn:  Jerry Wills 

Term:                    The term ("Term") of this Sublease shall begin on the
                         Commencement Date and expire on December 31, 1998. 
                         Notwithstanding the foregoing, the Term shall cease 
                         upon, and shall not refer to any period of time after, 
                         termination of the Master Lease (whether pursuant to 
                         the terms of the Master Lease, by operation of law, or 
                         otherwise).

Permitted Uses:          Those Permitted Uses set forth in paragraph 5 of the
                         Master Lease.

Brokers:                 Shaun Burnett, Irving Hughes Group, Inc.


Exhibits:                EXHIBIT A - Master Lease
                         EXHIBIT B - Premises Depiction 
                         EXHIBIT B-1 - Building Common Areas Depiction 
                         EXHIBIT C - Work List
                         EXHIBIT D - Exit Assessment 


                                     ii

<PAGE>

                              TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                 PAGE
<S>                                                                              <C>
ARTICLE 1 - PREMISES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  1
     1.1    Demise of Premises . . . . . . . . . . . . . . . . . . . . . . . . . .  1
     1.2    Condition of Premises. . . . . . . . . . . . . . . . . . . . . . . . .  2
          1.2.1     Physical Condition . . . . . . . . . . . . . . . . . . . . . .  2
          1.2.2     Environmental Assessment . . . . . . . . . . . . . . . . . . .  2
          1.2.3     No Representations . . . . . . . . . . . . . . . . . . . . . .  2
     1.3  Validity of Master Lease . . . . . . . . . . . . . . . . . . . . . . . .  2

ARTICLE 2 - TERM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  3

ARTICLE 3 - SUBLESSEE'S PAYMENT OBLIGATIONS. . . . . . . . . . . . . . . . . . . .  3
     3.1    Monthly Base Rent. . . . . . . . . . . . . . . . . . . . . . . . . . .  3
     3.2    Net Rental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  3

ARTICLE 4 - [INTENTIONALLY DELETED]. . . . . . . . . . . . . . . . . . . . . . . .  4

ARTICLE 5 - USE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  4

ARTICLE 6 - ALTERATIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  4

ARTICLE 7 - RIGHTS AND DUTIES OF SUBLESSEE . . . . . . . . . . . . . . . . . . . .  5
     7.1    Sublease Subject to Master Lease . . . . . . . . . . . . . . . . . . .  5
     7.2    Exclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     7.3    Time for Notice. . . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     7.4    Sublessor's Obligations. . . . . . . . . . . . . . . . . . . . . . . .  6
     7.5    Use of Building Common Areas . . . . . . . . . . . . . . . . . . . . .  6
     7.6    Entry by Sublessor . . . . . . . . . . . . . . . . . . . . . . . . . .  6

ARTICLE 8 - INDEMNIFICATION. . . . . . . . . . . . . . . . . . . . . . . . . . . .  7

ARTICLE 9 - INSURANCE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  7

ARTICLE 10 - DEFAULTS AND REMEDIES . . . . . . . . . . . . . . . . . . . . . . . .  7

ARTICLE 11 - NOTICES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  7

ARTICLE 12 - ASSIGNMENT AND SUBLETTING . . . . . . . . . . . . . . . . . . . . . .  8

ARTICLE 13 - REPAIRS AND MAINTENANCE . . . . . . . . . . . . . . . . . . . . . . .  8
</TABLE>

                                       i


<PAGE>

<TABLE>
<CAPTION>
                                                                                 PAGE
<S>                                                                              <C>
ARTICLE 14 - DAMAGE AND DESTRUCTION. . . . . . . . . . . . . . . . . . . . . . . .  8
     14.1    Termination of Master Lease . . . . . . . . . . . . . . . . . . . . .  8
     14.2    Continuation of Sublease  . . . . . . . . . . . . . . . . . . . . . .  8

ARTICLE 15 - CONDEMNATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     15.1    Total Condemnation. . . . . . . . . . . . . . . . . . . . . . . . . .  9
     15.2    Partial Condemnation. . . . . . . . . . . . . . . . . . . . . . . . .  9
     15.3    Sublessee's Award . . . . . . . . . . . . . . . . . . . . . . . . . .  9

ARTICLE 16 - SURRENDER OF PREMISES . . . . . . . . . . . . . . . . . . . . . . . .  9

ARTICLE 17 - MISCELLANEOUS . . . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     17.1    Entire Agreement. . . . . . . . . . . . . . . . . . . . . . . . . . .  9
     17.2    Captions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     17.3    Master Landlord's Consent . . . . . . . . . . . . . . . . . . . . . . 10
     17.4    Authority . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     17.5    Attorneys' Fees . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     17.6    Broker. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
</TABLE>


                                       ii

<PAGE>

                               SUBLEASE AGREEMENT


     THIS SUBLEASE AGREEMENT ("Sublease") is entered as of the Effective Date 
by and between Sublessor and Sublessee.

     THE PARTIES ENTER this Sublease on the basis of the following facts, 
understandings and intentions:

     A.   Master Landlord is the current Landlord of the Premises.  Sublessor 
is presently the Tenant of the Premises pursuant to the Master Lease.  A copy 
of the Master Lease with all amendments, exhibits and addenda thereto, is 
attached hereto as EXHIBIT A and incorporated herein by this reference.

     B.   Sublessor desires to sublease the Premises to Sublessee and 
Sublessee desires to sublease the Premises from Sublessor on all of the 
terms, covenants and conditions set forth herein.

     C.   All of the terms and definitions in the Defined Terms of the Basic 
Sublease Information of this Sublease are incorporated herein by this 
reference. Unless otherwise defined herein or the context otherwise requires, 
all capitalized terms shall have the meanings given them in the Master Lease.

     NOW, THEREFORE, IN CONSIDERATION of the mutual covenants and promises of 
the parties, the parties hereto agree as follows:

                              ARTICLE 1 - PREMISES

     1.1  DEMISE OF PREMISES.  Sublessor hereby subleases to Sublessee and 
Sublessee hereby subleases from Sublessor the Premises, for the Term and upon 
all of the terms and conditions herein set forth.  The Premises shall be used 
by Sublessee for those uses specifically set forth in the Basic Sublease 
Information, subject to the terms and conditions of Section 5 of the Master 
Lease.  In addition, Sublessor shall lease to Sublessee, and Sublessee shall 
lease from Sublessor, any and all permanent improvements ("Improvements") in 
or on the Premises constructed and/or owned by Master Landlord and/or 
Sublessor upon all of the terms, covenants and conditions herein contained.  
As used herein, "Premises" shall include the Premises and the Improvements.  
The Premises represents sixty percent (60%) of the total space in the Master 
Premises, which shall be Sublessee's "Proportionate Share" of Operating 
Expenses and Taxes (as defined in Paragraph 3.2 of this Sublease).


                                       1

<PAGE>

     1.2  CONDITION OF PREMISES.

          1.2.1     PHYSICAL CONDITION.  Sublessor and Sublessee acknowledge 
and agree that Sublessee is currently the occupant of the Premises under a 
Sublease from Sunward, which expires immediately prior to the Commencement 
Date.  By occupying the Premises on the Commencement Date, Sublessee shall be 
deemed to have acknowledged that it accepts the Premises in their current 
condition.  As of the Effective Date, Sublessee acknowledges that Sublessee 
has conducted Sublessee's own investigation of the Premises and the physical 
condition thereof, which in Sublessee's judgment affect or influence 
Sublessee's use of the Premises and Sublessee's willingness to enter this 
Sublease and that neither Sublessor nor any of its employees or agents have 
made or shall have any liability for any representations or warranties, 
express or implied, with respect to the condition of the Premises.  Both 
parties hereby acknowledge and agree that the Premises shall be subleased in 
their "as is" condition as of the Effective Date.  On September 30, 1997 
Sublessor, Sublessee and Master Landlord performed a walk-through inspection 
of the Premises in order to document the condition of the Premises on the 
Commencement Date for purposes of Sublessee's restoration obligations upon 
surrender of the Premises at the expiration of the Sublease Term ("Entrance 
Assessment").  As soon as practicable, Sublessor and Sublessee shall prepare, 
and both parties shall sign, a list of any additional work or repairs to be 
performed in order to restore the Premises from its current condition to the 
surrender condition required of Sublessee at expiration of the Term of this 
Sublease (the "Work List"), which shall be attached to the Sublease as 
EXHIBIT C.  In no event shall such additional work or repairs require 
Sublessee to improve the Premises to a condition better than that in which 
such Premises were received by Sublessee.  In addition to the restoration 
work set forth on the Work List, Sublessee agrees on the last day of the 
Sublease Term to surrender the Premises unto Sublessor in accordance with 
Article 16 of this Sublease. 

          1.2.2     ENVIRONMENTAL ASSESSMENT.  Prior to Sublessee's surrender 
of the Premises, Sublessee shall conduct an Exit Assessment, consisting of an 
updated Phase I Environmental Assessment and such other tests as are listed 
on the Exit Assessment attached hereto as EXHIBIT D.  Sublessor shall receive 
a copy of the report(s) of the Sublessee's Exit Assessment, and said 
report(s) shall be evidence of the physical condition of the Premises upon 
Sublessee's surrender of the Premises.  The cost of the Sublessee's Exit 
Assessment shall be paid by Sublessee.  Sublessee's Exit Assessment shall be 
performed by an independent environmental consultant reasonably acceptable to 
Sublessor.

          1.2.3     NO REPRESENTATIONS.  Sublessee and Sublessor recognize 
and agree that Sublessor would not sublease the Premises to Sublessee and 
Sublessee would not sublease the Premises from Sublessor except on an "as is" 
basis and acknowledges that neither Sublessee nor Sublessor has made any 
representations of any kind, express or implied, in connection with the 
Improvements or physical conditions on, or bearing on, the Premises, 
including without limitation the suitability of the Premises for Sublessee's 
purposes.  Sublessee further recognizes and agrees that neither Sublessor nor 
Master Landlord shall be required to perform any work of construction, 
alteration or maintenance of or to the Premises except as set forth in the 
Master Lease.

     1.3  VALIDITY OF MASTER LEASE.  Sublessor hereby warrants that the 
Master Lease attached hereto as EXHIBIT A is complete and in full force and 
effect, and that Sublessor is not in material default thereunder beyond 
expiration of any applicable cure or notice period, and that the area which 
is the subject of the Sublease has not been previously assigned or subleased 
by Sublessor.


                                       2

<PAGE>

                               ARTICLE 2 - TERM

          The term of this Sublease shall be for the Term set forth in the 
Basic Sublease Information provided that upon full execution of this Sublease 
by Sublessor and Sublessee, and provided that on or before the Commencement 
Date Sublessee provides Sublessor with (i) the certificates evidencing the 
insurance required by Article 9 of this Sublease and (ii) the first month's 
Base Rent, the Term shall commence on the Commencement Date and expire on 
September 30, 1998 ("Expiration Date").

                  ARTICLE 3 - SUBLESSEE'S PAYMENT OBLIGATIONS

     3.1  MONTHLY BASE RENT.  The Monthly Base Rent shall be payable in 
advance in equal monthly installments in accordance with the schedule for 
payment of Monthly Base Rent set forth in the Basic Sublease Information, 
commencing with the Rent Commencement Date.  Upon the execution of this 
Sublease by Sublessor and Sublessee, Sublessee shall deposit with Sublessor 
prepaid Rent in an amount equal to Thirty-Four Thousand Five Hundred 
Ninety-Six and 40/100's Dollars ($34,596.40) for the first month's Base Rent 
("Prepaid Rent").  Sublessee shall thereafter pay to Sublessor the monthly 
Base Rent in advance, on or before the first day of each month, beginning on 
the first day of the calendar month succeeding the Commencement Date.  Base 
Rent and any additional rent due hereunder shall be payable to Sublessor, 
without further notice or demand and without deduction or offset, in lawful 
money of the United States of America at the address specified in the Basic 
Sublease Information or at such other address as Sublessor may from time to 
time designate in writing.  If the Term shall end on a day other than the 
last day of a calendar month, then Rent for the last month of the Term shall 
be prorated on a per diem basis, with respect to the portions of the last 
fractional calendar month included in the Term.  

     3.2  NET RENTAL.  In addition to Monthly Base Rent, Sublessee shall be 
responsible for Sublessee's Proportionate Share (as set forth in the Basic 
Sublease Information), of Building Operating Expenses and Taxes and all other 
additional rent which may be imposed, at any time, on Sublessor pursuant to 
the Master Lease; provided that Sublessee shall not be responsible for any 
penalties, interest or other costs incurred by Sublessor under the Master 
Lease that are caused by Sublessor's failure to pay rent to Master Landlord 
in a timely manner in accordance with the Master Lease, unless such failure 
is cause by Sublessee's default or failure to make timely payments to 
Sublessor in accordance with this Sublease.  As used herein, "Sublease Rent" 
shall include Base Rent, Sublessee's Proportionate Share of Building 
Operating Expenses and Taxes, as defined below, and all other amounts payable 
by Sublessee to Sublessor hereunder.   Sublessee shall be responsible for 
Sublessee's Proportionate Share of all such costs and expenses for each and 
every month of the Sublease Term. Sublessee shall pay its Proportionate Share 
of Building Operating Expenses and Taxes no later than thirty (30) days 
following Sublessee's receipt of written demand therefor.

     "Building Operating Expenses and Taxes" shall consist of (1) all real 
property taxes, insurance premiums, Common Area Expenses, Common Area 
Assessments and other similar charges or expenses incurred by Sublessor 
pursuant to the Master Lease; (2) any personal property taxes payable by 
Sublessor in respect of the Premises or any trade fixtures, furnishings, 
equipment or other personal property either on the Premises or owned by 
Sublessee wherever located; and (3) Building Common Area Costs.  


                                       3

<PAGE>

     "Building Common Area Costs" shall mean all costs and expenses of 
whatever kind or nature incurred by Sublessor in connection with repair or 
maintenance of the Building Common Area or any other portion of the Building 
other than the portion of the Master Premises currently occupied by Sublessor 
("Sublessor's Premises") (and not including Sublessor's personal property or 
trade fixtures located in any part of the Building or Common Areas), 
including without limitation: (i) all costs of maintenance, repair, waste 
disposal, janitorial, security, landscaping, and HVAC or other common utility 
or service maintenance; (ii) any and all costs of maintenance and repair 
required to be performed by Sublessor pursuant to Section 11.1 of the Master 
Lease, BUT EXCLUDING those costs arising from maintenance and repair of the 
interior and nonstructural portions of Sublessor's Premises; and (iii) all 
charges for heat, water, sewer, gas, electricity, ventilating, 
air-conditioning and other utilities and similar services to the Building 
that are not separately metered to the Premises. Notwithstanding anything to 
the contrary herein, Building Operating Costs, shall not include:  (i) any 
capital expenditures made pursuant to Section 11.3(b) of the Master Lease (to 
the extent that Sublessor receives a rent credit from Master Landlord for 
such expenditure); (ii) costs incurred due to violation of any terms or 
conditions of the Master Lease, this Sublease or any other lease relating to 
any portion of the Building; (iii) costs of any repair for which Sublessor 
receives reimbursement from insurance proceeds or the Master Lessor or any 
other third party (other than through its Proportionate Share of Building 
Operating Expenses and Taxes); (iv) damage and repairs necessitated by the 
gross negligence or willful misconduct of Sublessor or Sublessor's officers, 
employees, agents or contractors; (v) reserves by Sublessor (not Master 
Lessor) for the repair, replacement or improvement of the Master Premises or 
any portion thereof; (vi) all Annual Base Rent due under the Master Lease; 
(vii) all costs and expenses incurred in connection with any sublease and/or 
assignment negotiations and transactions with present or prospective 
subtenants or other occupants or assignees of the Master Premises (except for 
subtenants or assignees of Sublessee's interest in this Sublease or the 
Premises); (viii) costs and expenses incurred in renovating or otherwise 
improving, decorating, painting or redecorating any portion of the 
Sublessor's Premises or otherwise incurred for the sole benefit of Sublessor 
or the Sublessor's Premises; (ix) any costs, fines, or penalties incurred due 
to violations by Sublessor or other subtenant of the Master Premises of any 
governmental rule or authority, this Sublease or any other lease in the 
Project, or due to Landlord's negligence or willful misconduct; (x) wages, 
salaries, or other compensation paid to any employees of Sublessor; (xii) 
Sublessor's general corporate overhead and administrative expenses and (xiii) 
expenses incurred by Sublessor in connection with services, utilities or 
other benefits to Sublessor, or its agents, employees, officers, directors or 
invitees in the Building, which are not offered to Sublessee or are not of 
the nature of services, utilities or benefits generally provided to tenants 
of industrial premises in the vicinity of the Building.  Any capital 
expenditures included in Building Common Area Costs shall be amortized on a 
straight line basis over the term of the Master Lease, and Sublessee shall be 
liable only for that portion allocable to the remaining term of this Sublease.

                                   ARTICLE 4

                            [INTENTIONALLY DELETED]

                                      4

<PAGE>

                                ARTICLE 5 - USE

     The Premises are to be used for the Permitted Uses, and for no other 
purpose or business without the prior written consent of Sublessor.  In no 
event shall the Premises be used for a purpose or use prohibited by the 
Master Lease.

                            ARTICLE 6 - ALTERATIONS

     Sublessee shall not, without Sublessor's prior written consent, which 
consent shall not be unreasonably withheld by Sublessor, make or cause to be 
made any alterations, additions or improvements to the Premises (or any 
changes to the Improvements) except for interior non-structural alterations 
not exceeding Ten Thousand ($10,000) in cumulative costs during the Term of 
this Sublease.  It shall be deemed reasonable for Sublessor to withhold its 
consent to any alterations unless and until Sublessee delivers to Sublessor 
reasonable security for the cost of removal of the alterations.  All 
alterations, additions or improvements requiring Master Landlord's consent 
shall also require Sublessor's prior written consent.  As part of such 
consent, Sublessee shall also obtain Master Landlord's written notice 
regarding whether removal of such alterations will be required by Master 
Landlord as part of the surrender obligations under the Master Lease.  
Sublessee shall remove all alterations required to be removed by Master 
Lessor or Sublessor, and repair all damage caused thereby, prior to 
expiration of the Term of this Sublease.  Sublessee shall defend, indemnify 
and hold harmless Sublessor from all liabilities, including restoration 
charges, which may be imposed by Master Landlord or other parties due to 
Sublessee's alterations, additions or improvements.


                                       5

<PAGE>


                   ARTICLE 7 - RIGHTS AND DUTIES OF SUBLESSEE

     7.1  SUBLEASE SUBJECT TO MASTER LEASE.  It is expressly understood, 
acknowledged and agreed by Sublessee that this Sublease shall incorporate by 
reference the terms, conditions and covenants of the Master Lease, except as 
excluded in Section 7.2 below, modified as appropriate in the circumstances 
so as to make such Sections applicable only to the subleasing hereunder by 
Sublessor of the Premises during the Term of this Sublease.  Sublessee shall 
be subject to, bound by and comply with all of said Sections of the Master 
Lease with respect to the Premises accruing during the Term of this Sublease, 
and shall satisfy all such terms and conditions of the Master Lease for the 
benefit of both Sublessor and Master Landlord, it being understood and agreed 
that wherever in the Master Lease the word "Tenant" appears, for the purposes 
of this Sublease, the word "Sublessee" shall be substituted (subject to the 
limitations set forth in this Sublease), wherever in the Master Lease the 
word "Landlord" appears, for the purposes of this Sublease, the words "Master 
Landlord" (and, as applicable hereunder, "Sublessor") shall be substituted; 
and wherever in the Master Lease the word "Premises" appears, for the 
purposes of this Sublease, the words "Master Premises" shall be substituted; 
and that upon the breach of any of said terms, conditions or covenants of the 
Master Lease by Sublessee or upon the failure of Sublessee to pay Rent or 
comply with any of the provisions of this Sublease, Sublessor may exercise 
any and all rights and remedies granted to Master Landlord by the Master 
Lease.  Sublessee expressly acknowledges, notwithstanding anything to the 
contrary in this Sublease, that Sublessee's duty to indemnify, protect, 
defend and hold Sublessor harmless from and against any and all claims, 
liabilities, penalties, losses or expenses (including reasonable attorneys 
fees and costs) pursuant to this Sublease, and as more specifically set forth 
in Section 14 of the Master Lease, shall include Sublessor's duty to 
indemnify, defend, protect and hold Master Landlord harmless from and against 
any and all claims, liabilities, penalties, forfeitures, losses or expenses 
(including attorneys' fees and costs).  Sublessor shall indemnify, protect, 
defend and hold Sublessee harmless from and against any and all claims, 
liabilities, penalties, forfeitures, losses or expenses (including attorneys' 
fees and costs) arising from Sublessor's breach or failure to perform any 
obligation under the Master Lease that is caused by:  (a) Sublessor's breach 
or failure to perform under this Sublease; or (b) any negligent or tortious 
act or omission of Sublessor, its officers, agents, employees, invitees or 
contractors relating to the Premises.  

          It is further understood and agreed that Sublessor has no duty or 
obligation to Sublessee under the aforesaid Sections of the Master Lease 
other than to maintain the Master Lease in full force and effect during the 
term of this Sublease and to pay the difference between the Sublease Rent and 
the Rent due and payable under the Master Lease; provided, however, that 
Sublessor shall not be liable to Sublessee for any earlier termination of the 
Master Lease which is not due to the fault of Sublessor.  In the event of any 
conflict between this Sublease and the Master Lease, the more restrictive 
provision shall control, as between Sublessor and Sublessee.  Whenever the 
provisions of the Master Lease incorporated as provisions of this Sublease 
require the written consent of Landlord, said provisions shall be construed 
to require the written consent of both Master Landlord and Sublessor.  
Sublessee hereby acknowledges that it has read and is familiar with all the 
terms of the Master Lease, and agrees that this Sublease is subordinate and 
subject to the Master Lease and that any termination thereof without the 
fault of Sublessor shall likewise terminate this Sublease.

     7.2  EXCLUSIONS.  The terms and provisions of the following Sections of 
the Master Lease are not incorporated into this Sublease:  Master Lease 
Sections 2.1, 3.1, 3.2, 4.1, 4.2, 4.3, 9, 17.1, 17.4, 50.3.  Section 37.1 
shall apply only to Master Landlord.


                                       6

<PAGE>

     7.3  TIME FOR NOTICE.  The time limits provided for in the provisions of 
the Master Lease for the giving of notice, making of demands, performance of 
any act, condition or covenant, or the exercise of any right, remedy or 
option, are amended for the purposes of this Sublease by lengthening or 
shortening the same in each instance by five (5) days, as appropriate, so 
that notices may be given, demands made, or any act, condition or covenant 
performed, or any right, remedy or option hereunder exercised, by Sublessor 
or Sublessee, as the case may be, within the time limit relating thereto 
contained in the Master Lease.  If the Master Lease allows only five (5) days 
or less for Sublessor to perform any act, or to undertake to perform such 
act, or to correct any failure relating to the Premises or this Sublease, 
then Sublessee shall nevertheless be allowed three (3) days to perform such 
act, undertake such act and/or correct such failure.

     7.4  SUBLESSOR'S OBLIGATIONS.  It shall be the obligation of Master 
Landlord (i) to provide or cause to be provided all services to be provided 
by Landlord under the terms of the Master Lease and (ii) to satisfy all 
obligations and covenants of Master Landlord made in the Master Lease, 
including without limitation, the obligations of Sections 11.3 and 15.2 of 
the Master Lease. Sublessee acknowledges that Sublessor shall be under no 
obligation to provide any such services or satisfy any such obligations or 
covenants; provided, however, Sublessor, upon written notice by Sublessee, 
shall promptly and diligently attempt to enforce all obligations of Master 
Landlord under the Master Lease, provided that Sublessee reimburses Sublessor 
for all reasonable costs and expenses incurred in connection therewith.

     7.5  USE OF BUILDING COMMON AREAS.  Sublessee shall comply with all 
reasonable and non-discriminatory rules and regulations established by 
Sublessor with respect to use of the Building Common Areas, and shall insure 
compliance therewith by all of Sublessee's employees, contractors and 
invitees.  Without limiting the generality of the foregoing, Sublessee shall 
insure that there is no consumption of food by Sublessee's employees, agents, 
contractors or invitees in the lobby, and shall promptly comply with all 
reasonable requests of Sublessor intended to comply with Good Laboratory 
Practices and/or Good Manufacturing Practices.  Sublessor shall maintain the 
Building Common Area in a clean, safe and sanitary condition.

     7.6  ENTRY BY SUBLESSOR.  Sublessor shall have the right, upon at least 
24 hours advance notice (except in an emergency, in which case no notice 
shall be required) to enter upon the Premises for purposes of maintenance and 
repair, and to ensure compliance by Sublessee with its obligations pursuant 
to this Sublease.  Sublessee shall provide Sublessor with two keys (including 
card keys) to all doors of the Premises in order to facilitate such entry.  
In addition, Sublessor shall have the right to show the Premises to 
prospective lenders, partners, subtenants and their assigns during normal 
business hours on at least 24 hours' prior notice. 

                          ARTICLE 8 - INDEMNIFICATION

     Sublessee covenants to indemnify, defend, protect and hold Sublessor, 
its agents, officers, employees, and contractors harmless from and against 
(i) any and all claims, causes of action, obligations, liabilities, costs and 
expenses (including reasonable attorneys' fees and costs) to the extent 
arising out of or in connection with Sublessee's use or occupancy of the 
Premises, the Common Areas and /or the Building Common Areas before or after 
the commencement of the Term of this Sublease, and (ii) the breach of this 
Sublease (or, to the extent incorporated herein, the Master Lease) by 


                                      7

<PAGE>

Sublessee, its employees, agents, contractors or invitees.  Sublessor 
covenants to indemnify, defend, protect and hold Sublessee harmless from and 
against any and all claims, causes of action, obligations, liabilities, costs 
and expenses (including reasonable attorney fees and costs) to the extent 
arising out of or in connection with Sublessor's use or occupancy of the 
Sublessor's Premises, Common Areas and/or the Building Common Areas before or 
after the commencement of the Term of this Sublease and (iii) the breach of 
this Sublease or the Master Lease by Sublessor, its employees, agents, 
contractors or invitees.

                            ARTICLE 9 - INSURANCE

     Sublessee covenants to obtain and maintain the insurance policies 
required to be maintained by Sublessor under Section 15.1, 15.2(c), 15.2(d) 
and 15.3 of the Master Lease naming Sublessor as an additional insured; to 
provide Sublessor with certificates evidencing such insurance; and not to 
merit cancellation or termination of such required insurance policies without 
giving at least fifteen (15) days prior written notice to Sublessor and 
Master Landlord.  Sublessee shall deliver to Sublessor, from time to time and 
upon Sublessor's or Master Landlord's reasonable written request, 
certificates of insurance indicating that the required policies of insurance 
are in full force and effect throughout the entire term of this Sublease.  
All insurance policies required to be carried by Sublessor pursuant to the 
Master Lease shall be carried by Sublessee, covering Sublessee's liability, 
and all such policies shall be written in accordance with the requirements 
for such insurance set forth in Section 15.1 of the Master Lease.

                       ARTICLE 10 - DEFAULTS AND REMEDIES

     In the event of a default by Sublessee, Sublessor shall have all of the 
rights and remedies against Sublessee as are set forth in Section 19 of the 
Master Lease as though Sublessor were the landlord named therein and 
Sublessee was the tenant named therein.

                              ARTICLE 11 - NOTICES

     All notices or correspondence provided for herein shall be in writing 
and shall be sent by certified mail, postage prepaid, return receipt 
requested, or by a nationally-recognized overnight delivery company which 
provides a receipt evidencing delivery, in which event they shall be deemed 
received on the date of delivery as evidenced by the receipt.  The Master 
Landlord's, Sublessor's and Sublessee's addresses for written notices 
required to be given hereunder shall be the addresses set forth in the Basic 
Sublease Information, or at such other place designated by advance written 
notice delivered in accordance with the foregoing.


                                       8

<PAGE>

                     ARTICLE 12 - ASSIGNMENT AND SUBLETTING

     Sublessee shall not sell, assign, encumber, sublet, hypothecate or 
otherwise transfer by operation of law or otherwise this Sublease or the 
Sublessor's interest in and to the Premises (but not including any of 
Sublessee's trade fixtures or other personal property in the Premises) 
without first procuring the written consent of the Sublessor, which consent 
may be withheld in Sublessor's sole and absolute discretion.  Any such sale, 
assignment, encumbrance, sublease or other transfer in violation of the terms 
of this Sublease shall be void and shall be of no force or effect.  In the 
event Sublessor authorizes such a sublease, assignment or transfer, Sublessee 
shall remain fully liable for the Sublessee's obligations under this 
Sublease. Notwithstanding the foregoing, Sublessee shall have the right, 
after written notice to Sublessor, to assign or sublet all or any portion of 
the Premises to any entity controlling, controlled by or under common control 
with Sublessee or any successor by merger or consolidation, provided that: 
(1) the transferee agrees in writing to assume all of Sublessee's obligations 
under the Sublease, and (2) the original Sublessee shall not be released from 
any of its obligations hereunder.  

                      ARTICLE 13 - REPAIRS AND MAINTENANCE

     Sublessee shall, at Sublessee's sole expense, keep the Premises in good 
order and sanitary condition, and repair any damage thereto caused by 
Sublessee or Sublessee's agents, employees, contractors or invitees.  
Sublessee acknowledges that Sublessor is under no duty to make repairs or 
improvements to the Premises, and Sublessee hereby waives any right it may 
have at law or in equity to enforce the same.  Notwithstanding the foregoing, 
to the extent Master Landlord is obligated under the Master Lease to make any 
maintenance or repairs in or to the Premises or Building, Sublessor, upon 
written notice by Sublessee, shall diligently attempt to enforce such 
obligations of Master Landlord, provided that Sublessee reimburses Sublessor 
for all reasonable costs and expenses incurred in connection therewith.  
Notwithstanding the foregoing, if such maintenance or repairs affect the use 
and enjoyment of the Building Common Area, such costs and expenses of 
enforcement shall be paid by Sublessor and Sublessee in proportion to their 
relative interests in the Building.  

                      ARTICLE 14 - DAMAGE AND DESTRUCTION

     14.1 TERMINATION OF MASTER LEASE.  If the Premises is damaged or 
destroyed and Master Landlord exercises any option to terminate the Master 
Lease, if any, this Sublease shall terminate as of the date of the 
termination of the Master Lease.  So long as Sublessee is not in default 
under this Sublease beyond the applicable notice and cure period for such 
default on the date of such damage or destruction, Sublessee shall have the 
same rights of termination under this Sublease as Sublessor may have to 
terminate the Master Lease upon an event of damage or destruction under the 
Master Lease.  In the event Sublessee is in default under this Sublease 
beyond the applicable notice and cure period for such default on the date of 
such damage or destruction, then Sublessor shall have the right to exercise 
any termination right granted to Sublessor under Section 15 of the Master 
Lease.

     14.2 CONTINUATION OF SUBLEASE.  If the Master Lease is not terminated 
following any damage or destruction as provided above, this Sublease shall 
remain in full force and effect.  Sublessee shall be obligated to fulfill any 
repair obligations of Sublessor with respect to the Premises; provided, 
however, that (i) Sublessor shall diligently enforce any obligation of Master 
Landlord to rebuild the 


                                      9

<PAGE>

Premises in accordance with the Master Lease; (ii) Sublessor shall make 
available to Sublessee any insurance proceeds Sublessor receives as a result 
of damage or destruction of the Premises; and (iii) Sublessee shall be 
entitled to abatement of Rent on a proportionate basis (based on the degree 
to which Sublessee's use of the Premises is impaired as compared to the 
impairment of Sublessor's use of Sublessor's Premises) to the extent that 
Sublessor's Rent is abated under the Master Lease.  In the event that the 
damage cannot reasonably be repaired by the date that is 90 days prior to the 
expiration of the Term of this Sublease, then either party may terminate this 
Sublease by written notice to the other party.

                           ARTICLE 15 - CONDEMNATION

     15.1 TOTAL CONDEMNATION.  If all of the Premises are condemned by 
eminent domain, inversely condemned or sold in lieu of condemnation, for any 
public or a quasi-public use or purpose ("Condemned" or "Condemnation"), this 
Sublease shall terminate as of the date of title vesting in such proceeding, 
and Rent shall be adjusted to the date of termination.

     15.2 PARTIAL CONDEMNATION.  If any portion of the Premises is Condemned, 
and Master Landlord exercises any option to terminate the Master Lease, this 
Sublease shall automatically terminate as of the date of the termination of 
the Master Lease.  If this Sublease is not terminated following any such 
Condemnation, this Sublease shall remain in full force and effect and 
Sublessee shall promptly restore the Premises to the extent of any 
Condemnation proceeds recovered by Sublessor and made available by Sublessor 
to Sublessee for restoration, in addition, Sublessor shall diligently enforce 
any rights under the Master Lease to require Master Landlord to rebuild the 
Master Premises. Rent shall be equitably adjusted to take into account 
interference with Sublessee's ability to conduct its operations on the 
Premises as a result of the Premises being Condemned, pursuant to the terms 
and conditions of Section 14 of the Master Lease.  

     15.3 SUBLESSEE'S AWARD.  Subject to the provisions of the Master Lease, 
Sublessee shall have the right to recover from the condemning authority, such 
compensation as may be separately awarded to Sublessee in connection with 
such Condemnation proceedings.

                       ARTICLE 16 - SURRENDER OF PREMISES

     Sublessee shall peaceably surrender the Premises (including, without 
limitation, the Improvements) to Sublessor upon expiration or earlier 
termination of this Sublease, broom-clean and in as good a condition as when 
Sublessee took possession and with the Work List work completed, except for 
(i) reasonable wear and tear, (ii) loss by fire or other casualty, and (iii) 
loss by condemnation.  Sublessee shall remove Sublessee's personal property 
and, if Master Landlord, by written notice delivered to Sublessee at least 
sixty (60) days prior to the expiration of the Sublease, requires removal of 
Sublessee's lab drops from the Premises as a condition to Sublessor's 
surrender of the Building under the Master Lease (as permitted by the 
surrender provisions of the Master Lease), then Sublessee shall also remove 
such lab drops at Sublessee's cost and expense, upon the expiration or 
earlier termination of this Sublease and promptly repair all damage to the 
Premises or Building caused by such removal.

     If Sublessee abandons the Premises, any of Sublessee's personal property 
left on the Premises shall be deemed to be abandoned, and, at Sublessor's 
option, title shall pass to Sublessor under this Sublease as by a bill of 
sale. If Sublessee abandons the Premises and Sublessor elects to remove all 
or 


                                      10


<PAGE>

any part of Sublessee's personal property, the reasonable cost of removal, 
including repairing any damage to the Premises or Building caused by such 
removal, shall be paid by Sublessee.  

                           ARTICLE 17 - MISCELLANEOUS

     17.1 ENTIRE AGREEMENT.  This Sublease and the applicable portions of the 
Master Lease contained by reference herein, contain all of the covenants, 
conditions and agreements between the parties concerning the Premises, and 
shall supersede any and all prior correspondence, agreements and 
understandings concerning the Premises, both oral and written.  No addition 
or modification of any term or provision of this Sublease shall be effective 
unless set forth in writing and signed by both Sublessor and Sublessee.

     17.2 CAPTIONS.  All captions and headings in this Sublease are for the 
purposes of reference and convenience and shall not limit or expand the 
provisions of this Sublease.

     17.3 MASTER LANDLORD'S CONSENT.  This Sublease is conditioned upon 
Master Landlord's written approval of this Sublease prior to the Commencement 
Date.  If Master Landlord refuses to consent to this Sublease, then this 
Sublease shall be deemed void and of no effect, in which event the parties 
shall be discharged from all obligations hereunder and Sublessor shall return 
the Prepaid Rent, if previously delivered to Sublessor, to Sublessee; 
provided, however, that if Master Landlord acts unreasonably in withholding 
such consent, Sublessor shall reasonably attempt to enforce Sublessor's 
rights under Section 47.1 of the Master Lease.

     17.4 AUTHORITY.  Each person executing this Sublease on behalf of a 
party hereto represents and warrants that he or she is authorized and 
empowered to do so and to thereby bind the party on whose behalf he or she is 
signing.

     17.5 ATTORNEYS' FEES.  In the event either party shall bring any action 
or proceeding for damages or for an alleged breach of any provision of this 
Sublease to recover rents, or to enforce, protect or establish any right or 
remedy hereunder, the prevailing party shall be entitled to recover 
reasonable attorneys' fees and court costs as part of such action or 
proceeding.

     17.6 BROKER.  Sublessor shall be responsible for payment of any and all 
finder's fees or commissions to Shaun Burnett of Irving Hughes Group, Inc. 
("Broker") in connection with this Sublease.  Each party warrants and 
represents that it has had no dealings with any real estate broker, agent or 
finder other than Broker in connection with the negotiation of this Sublease, 
and that it knows of no other real estate broker or agent who is entitled to 
any commission or finder's fee in connection with the Premises or this 
Sublease.  Each party shall indemnify and hold the other harmless from and 
against any and all claims, demands, losses, liabilities, lawsuits, 
judgments, costs and expenses (including without limitation, attorneys' fees 
and costs) arising from any claim for a leasing commission or equivalent 
compensation alleged to be owing on account of the indemnifying party's 
dealings with any real estate broker or agent in connection with the Premises 
or this Sublease.

     17.7 COUNTERPARTS.  This Sublease may be executed in any number of 
counterparts, each of which shall be deemed to be an original and all of 
which taken together shall comprise but a single instrument.


                                       11

<PAGE>

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                                       12

<PAGE>

     IN WITNESS WHEREOF, the parties hereto have executed one (1) or more 
copies of this Sublease, effective as of the Effective Date.

                              "SUBLESSOR"

                              MOLECULAR BIOSYSTEMS, INC.
                              a Delaware corporation 


                              By:    /s/ Gerard A. Wills
                                     ----------------------------
                              Name:  Gerard A. Wills
                                     ----------------------------
                              Its:   Chief Financial Officer
                                     ----------------------------


                              "SUBLESSEE"

                              DURA PHARMACEUTICALS, INC.
                              a Delaware corporation


                              By:    /s/ M.R. Woodbury
                                     -----------------------------
                              Name:  M.R. Woodbury                   
                                     -----------------------------
                              Its:   Senior Vice President        
                                     -----------------------------




              [Remainder of This Page Intentionally Left Blank]


                                       13

<PAGE>


                                   EXHIBIT A

                                  MASTER LEASE


                                           
                                      A-1

<PAGE>

                                   EXHIBIT B

                                   PREMISES






                                      B-1


<PAGE>

                                       
                                  EXHIBIT B-1

                           COMMON AREA OF FIRST FLOOR





                                      B-2

<PAGE>

                                   EXHIBIT C

                                   WORK LIST

                                [To Be Attached]





                                      C-1

<PAGE>
                                   EXHIBIT D

                                EXIT ASSESSMENT


     I.   An updated Phase I Assessment shall be prepared by an independent 
consultant and shall be  consistent with the American Society for Testing 
Materials (ASTM) Standard E-1527 and shall, by its terms, allow the following 
parties to rely upon its conclusions:  Master Landlord, Sublessor and 
Sublessee.

     II.  An Interior Site Assessment consisting of a visual inspection of 
all surfaces (floors, walls, ceiling tiles, benches, interior of cabinets, 
etc.) for signs of contamination and deterioration.  Visual inspection of all 
sinks and readily accessible drain lines for signs of deterioration, loss of 
integrity and leakage.  The Interior Site Assessment shall include detailed 
written documentation of all observations and dated photos to document the 
existing condition thereof.

     III. A Wastewater Collection System Assessment consisting of a flush and 
clean-out of all discharge piping and traps with observation of effluent 
during the clean-out and, in the event that visual observation of the 
effluent indicates degradation of the Wastewater Collection System in excess 
of normal wear for a facility of similar age and use, videotaping of the 
Wastewater Collection System along with a written report for each ten foot 
(10') piping segment. 

                                      D-1