content: Page 1 of 8 pages
  
  
                                    UNITED STATES
                         SECURITIES AND EXCHANGE COMMISSION
                               Washington, D.C. 20549
  
  
  
  
                                      FORM 8-K
  
  
  
  
  
                                   CURRENT REPORT
  
       Pursuant to Section 13 to 15(d) of the Securities Exchange Act of 1934
  
  
          Date of Report (date of earliest event reported): April 21, 1997
  
  
  
                             MOLECULAR BIOSYSTEMS, INC.
               (Exact name of registrant as specified in its charter)
  
  
                            Delaware 1-10546 36-30878632
                (State or other juris- (Commission file (IRS employer
              diction of incorporation) number) identification number)
  
  
  
                10030 Barnes Canyon Road, San Diego, California 92121
                      (Address of principal executive offices)
  
  
         Registrant's telephone number, including area code: (619) 452-0681
  
  
  <PAGE>
  
  
  Item 5. Other Events.
  
       (1)  Stay of Action by the FDA
  
       On April 21, 1997,  United  States  District  Judge Paul L. Friedman of the
  United  States  District  Court for the  District of  Columbia  entered an order
  enjoining  the United  States  Food and Drug  Administration  (the  "FDA")  from
  continuing  any  approval  or  review  procedures   relating  to  the  Company's
  pre-market    approval    application   ("PMA")   for   FS069,   the   Company's
  second-generation  contrast agent for cardiac ultrasound imaging,  until 10 days
  after the FDA resolves the merits of citizen petitions previously filed with the
  FDA  by  plaintiffs,  Bracco  Diagnostics,  Inc.,  DuPont  Merck  Pharmaceutical
  Company,  ImaRx  Pharmaceutical  Corp.  and Sonus  Pharmaceuticals,  Inc.  These
  citizen petitions  requested the FDA to regulate all ultrasound imaging contrast
  agents either as drugs (as the plaintiffs' contrast agents under development are
  currently  classified)  or as medical  devices (as the Company's  ALBUNEX(R) and
  FS069 are  currently  classified).  On February  24,  1997,  the FDA's  advisory
  Radiological  Devices  Panel had  recommended  approval of the  Company' PMA for
  FS069.
  
       As  described  in Judge  Friedman's  opinion  accompanying  his order,  the
  purpose of the order is to grant "a limited  injunction  to preserve  the status
  quo  pending a decision  by the FDA as to how to treat all  ultrasound  contrast
  agents,  whether  as  medical  devices  or as drugs,  or to  provide a  rational
  explanation  for the  different  treatment  of the  products  at  issue."  Judge
  Friedman's order thus  identically  enjoins the FDA from continuing any approval
  or review  procedures  relating to any of the  plaintiffs'  respective  products
  until 10 days  after the FDA  resolves  the merits of the  plaintiffs'  citizens
  petitions.
  
       A copy of the Company's press release with respect to the stay of action by
  the FDA is attached to this Report as Exhibit 10.1.
  
       (2) Brand Name Announced for FS069
  
       On May 7, 1997, the Company and Mallinckrodt,  Inc., jointly announced that
  if and when  approved for sale by the FDA,  FS069 will be marketed in the United
  States under the brand name, "OPTISON(TM)." Mallinckrodt,  Inc. is the Company's
  licensee for marketing and  distributing  ALBUNEX(R) and OPTISON(TM)  throughout
  the world (except for Japan, Korea and Taiwan).
  
       A copy of  Mallinckrodt's  press release with respect to the brand name for
  FS069 is attached to this Report as Exhibit 10.2.
  
       (3) Patent Matters
  
       The Company has become aware of several  United  States  patents  issued to
  other  companies  covering  various  attributes  of   perfluorocarbon-containing
  imaging agents such as OPTISON(TM). Certain of these companies also are pursuing
  foreign  patent  protection.  Some of these  companies are  developing or may be
  developing   ultrasound   contrast   imaging  agents  that  would  compete  with
  OPTISON(TM).
  
       The patents and patent  applications  of these  other  companies  involve a
  number of complex legal and factual  issues that are currently  unresolved.  The
  Company  believes  that  there may be a  substantial  overlap  among many of the
  claims in their patents and that it is likely that there will be  administrative
  proceeding or  litigation  in the United  States and abroad to adjudicate  their
  conflicting  rights. The Company believes that it could become a party to one or
  more of these  actions,  which could take  several  years to conclude  and could
  result in a substantial cost to the Company.
  
  
  <PAGE>
  
  
  
       The Company believes that, for a variety of reasons, its  commercialization
  of  OPTISON(TM)  will not  infringe  any valid patent held by one of these other
  companies. Depending upon the particular patent claim, these reasons include (i)
  differences  between  OPTISON(TM)  and  the  subject  of  the  claim,  (ii)  the
  invalidity of the claim due to the existence of prior art,  (iii) the inadequacy
  of the claim's  specifications and (iv) lack of enablement.  The Company intends
  to  challenge  the  validity  of any such  patent  granted  to one of the  other
  companies if the patent is asserted  against the  Company,  and the Company will
  enforce its own patents if any product of one of the other  companies  infringes
  the Company's patent claims.
  
       If any patent granted to one of the other companies is asserted against the
  Company, litigation or administrative proceedings may be necessary to defend the
  Company  against  infringement  claims or to determine the  priority,  scope and
  validity of the other  company's  proprietary  rights.  Any such  litigation  or
  administrative  proceedings  could result in a substantial  cost to the Company;
  and  given  the  complexity  of the  legal  and  factual  issues,  the  inherent
  vicissitudes and uncertainty of litigation,  and other factors,  there can be no
  assurance of a favorable outcome.  An unfavorable  outcome could have a material
  adverse  effect on the Company's  business,  financial  condition and results of
  operations.  Moreover,  there  can be no  assurance  that,  in the  event  of an
  unfavorable  outcome,  the  Company  would be able to  obtain a  license  to any
  proprietary rights that may be necessary to commercialize OPTISON(TM), either on
  acceptable  terms or at all.  If the Company  were  required to obtain a license
  necessary to commercialize OPTISON(TM), the Company's failure or inability to do
  so would have a material  adverse  effect on the Company's  business,  financial
  condition and results of operations.
  
  
  <PAGE>
  
  
  
                                      Signature
  
       Pursuant to the  requirements  of the Securities  Exchange Act of 1934, the
  registrant  has duly  caused  this  report  to be  signed  on its  behalf by the
  undersigned hereunto duly authorized.
  
       Date:  May 9, 1997
  
  
       Molecular Biosystems, Inc.
  
  
  
  
       By  /s/ Gerard A. Wills
           Gerard A. Wills
           Vice President, Finance
              and Chief Financial Officer
  
  
  <PAGE>
  
  
                                    Exhibit Index
  
  
                                                                     Sequentially
                                                                         Numbered
  Exhibit            Description                                             Page
  
  10.1               Press release (April 22, 1997)                             6
  10.2               Press release (May 7, 1997)                                8
  
  
  <PAGE>
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metadata_filer: {"company-data": {"conformed-name": "MOLECULAR BIOSYSTEMS INC", "cik": "0000719598", "assigned-sic": "2835", "irs-number": "363078632", "state-of-incorporation": "DE", "fiscal-year-end": "0331"}, "filing-values": {"form-type": "8-K", "act": "34", "file-number": "001-10546", "film-number": "97599989"}, "business-address": {"street1": "10030 BARNES CANYON RD", "city": "SAN DIEGO", "state": "CA", "zip": "92121-2789", "phone": "6198242200"}, "mail-address": {"street1": "10030 BARNES CANYON ROAD", "city": "SAN DIEGO", "state": "CA", "zip": "92121"}}
text: Page 1 of 8 pages
  
                                    UNITED STATES
                         SECURITIES AND EXCHANGE COMMISSION
                               Washington, D.C. 20549
  
                                      FORM 8-K
  
                                   CURRENT REPORT
  
       Pursuant to Section 13 to 15(d) of the Securities Exchange Act of 1934
  
          Date of Report (date of earliest event reported): April 21, 1997
  
                             MOLECULAR BIOSYSTEMS, INC.
               (Exact name of registrant as specified in its charter)
  
                            Delaware 1-10546 36-30878632
                (State or other juris- (Commission file (IRS employer
              diction of incorporation) number) identification number)
  
                10030 Barnes Canyon Road, San Diego, California 92121
                      (Address of principal executive offices)
  
         Registrant's telephone number, including area code: (619) 452-0681
  Item 5. Other Events.
  
       (1)  Stay of Action by the FDA
  
       On April 21, 1997,  United  States  District  Judge Paul L. Friedman of the
  United  States  District  Court for the  District of  Columbia  entered an order
  enjoining  the United  States  Food and Drug  Administration  (the  "FDA")  from
  continuing  any  approval  or  review  procedures   relating  to  the  Company's
  pre-market    approval    application   ("PMA")   for   FS069,   the   Company's
  second-generation  contrast agent for cardiac ultrasound imaging,  until 10 days
  after the FDA resolves the merits of citizen petitions previously filed with the
  FDA  by  plaintiffs,  Bracco  Diagnostics,  Inc.,  DuPont  Merck  Pharmaceutical
  Company,  ImaRx  Pharmaceutical  Corp.  and Sonus  Pharmaceuticals,  Inc.  These
  citizen petitions  requested the FDA to regulate all ultrasound imaging contrast
  agents either as drugs (as the plaintiffs' contrast agents under development are
  currently  classified)  or as medical  devices (as the Company's  ALBUNEX(R) and
  FS069 are  currently  classified).  On February  24,  1997,  the FDA's  advisory
  Radiological  Devices  Panel had  recommended  approval of the  Company' PMA for
  FS069.
  
       As  described  in Judge  Friedman's  opinion  accompanying  his order,  the
  purpose of the order is to grant "a limited  injunction  to preserve  the status
  quo  pending a decision  by the FDA as to how to treat all  ultrasound  contrast
  agents,  whether  as  medical  devices  or as drugs,  or to  provide a  rational
  explanation  for the  different  treatment  of the  products  at  issue."  Judge
  Friedman's order thus  identically  enjoins the FDA from continuing any approval
  or review  procedures  relating to any of the  plaintiffs'  respective  products
  until 10 days  after the FDA  resolves  the merits of the  plaintiffs'  citizens
  petitions.
  
       A copy of the Company's press release with respect to the stay of action by
  the FDA is attached to this Report as Exhibit 10.1.
  
       (2) Brand Name Announced for FS069
  
       On May 7, 1997, the Company and Mallinckrodt,  Inc., jointly announced that
  if and when  approved for sale by the FDA,  FS069 will be marketed in the United
  States under the brand name, "OPTISON(TM)." Mallinckrodt,  Inc. is the Company's
  licensee for marketing and  distributing  ALBUNEX(R) and OPTISON(TM)  throughout
  the world (except for Japan, Korea and Taiwan).
  
       A copy of  Mallinckrodt's  press release with respect to the brand name for
  FS069 is attached to this Report as Exhibit 10.2.
  
       (3) Patent Matters
  
       The Company has become aware of several  United  States  patents  issued to
  other  companies  covering  various  attributes  of   perfluorocarbon-containing
  imaging agents such as OPTISON(TM). Certain of these companies also are pursuing
  foreign  patent  protection.  Some of these  companies are  developing or may be
  developing   ultrasound   contrast   imaging  agents  that  would  compete  with
  OPTISON(TM).
  
       The patents and patent  applications  of these  other  companies  involve a
  number of complex legal and factual  issues that are currently  unresolved.  The
  Company  believes  that  there may be a  substantial  overlap  among many of the
  claims in their patents and that it is likely that there will be  administrative
  proceeding or  litigation  in the United  States and abroad to adjudicate  their
  conflicting  rights. The Company believes that it could become a party to one or
  more of these  actions,  which could take  several  years to conclude  and could
  result in a substantial cost to the Company.
  The Company believes that, for a variety of reasons, its  commercialization
  of  OPTISON(TM)  will not  infringe  any valid patent held by one of these other
  companies. Depending upon the particular patent claim, these reasons include (i)
  differences  between  OPTISON(TM)  and  the  subject  of  the  claim,  (ii)  the
  invalidity of the claim due to the existence of prior art,  (iii) the inadequacy
  of the claim's  specifications and (iv) lack of enablement.  The Company intends
  to  challenge  the  validity  of any such  patent  granted  to one of the  other
  companies if the patent is asserted  against the  Company,  and the Company will
  enforce its own patents if any product of one of the other  companies  infringes
  the Company's patent claims.
  
       If any patent granted to one of the other companies is asserted against the
  Company, litigation or administrative proceedings may be necessary to defend the
  Company  against  infringement  claims or to determine the  priority,  scope and
  validity of the other  company's  proprietary  rights.  Any such  litigation  or
  administrative  proceedings  could result in a substantial  cost to the Company;
  and  given  the  complexity  of the  legal  and  factual  issues,  the  inherent
  vicissitudes and uncertainty of litigation,  and other factors,  there can be no
  assurance of a favorable outcome.  An unfavorable  outcome could have a material
  adverse  effect on the Company's  business,  financial  condition and results of
  operations.  Moreover,  there  can be no  assurance  that,  in the  event  of an
  unfavorable  outcome,  the  Company  would be able to  obtain a  license  to any
  proprietary rights that may be necessary to commercialize OPTISON(TM), either on
  acceptable  terms or at all.  If the Company  were  required to obtain a license
  necessary to commercialize OPTISON(TM), the Company's failure or inability to do
  so would have a material  adverse  effect on the Company's  business,  financial
  condition and results of operations.
  Signature
  
       Pursuant to the  requirements  of the Securities  Exchange Act of 1934, the
  registrant  has duly  caused  this  report  to be  signed  on its  behalf by the
  undersigned hereunto duly authorized.
  
       Date:  May 9, 1997
  
       Molecular Biosystems, Inc.
  
       By  /s/ Gerard A. Wills
           Gerard A. Wills
           Vice President, Finance
              and Chief Financial Officer
  Exhibit Index
  
                                                                     Sequentially
                                                                         Numbered
  Exhibit            Description                                             Page
  
  10.1               Press release (April 22, 1997)                             6
  10.2               Press release (May 7, 1997)                                8