OPTISON Off to a Solid Start in Ultrasound Imaging Market.

ST. LOUIS and SAN DIEGO--(BW HealthWire)--Jan. 28, 1998--OPTISON(TM), the next-generation ultrasound imaging agent manufactured by Molecular Biosystems Inc. (MBI) (NYSE:MB) and marketed by Mallinckrodt Inc. (NYSE:MKG), is meeting with good early acceptance among ultrasound specialists in healthcare settings, said Neil Muhilly, vice president-ultrasound for Mallinckrodt, during an analysts' briefing Tuesday on Mallinckrodt second quarter results.

"OPTISON(TM) received FDA clearance on December 31, and it already has been used in 100 hospitals," Muhilly said. "The indicated use for OPTISON(TM) is for cardiac ultrasound imaging procedures. The early indications are that our reorder rate is encouraging."

Muhilly said there are about 11 million ultrasound cardiac imaging procedures performed each year in the United States, and about 20 percent of the results are considered suboptimal. Mallinckrodt is optimistic about the potential for the product, Muhilly said, but it is too early to forecast sales for the first year in the market.

OPTISON(TM), the first of the perfluorocarbon containing ultrasound agents to reach the market, enables physicians to enhance resolution of anatomical structure where ultrasound alone is inadequate. The product is specifically indicated for use in patients with suboptimal echocardiograms to opacify the left ventricle and to improve the delineation of the left ventricular endocardial borders.

Ultrasound cardiac imaging has several advantages over other imaging methods. It is minimally invasive, relatively inexpensive and can quickly provide a real-time image.

OPTISON(TM) helps increase the effectiveness of echocardiography in diagnosing heart disease by introducing gas-filled microspheres into the blood. The microspheres travel in the bloodstream to the left ventricle of the heart, where the microspheres reflect the soundwaves generated from ultrasound equipment, enabling the development of a clearer, more diagnostic ultrasound image. Overall, the reported adverse events with OPTISON(TM) were similar in type and frequency to those reported with ALBUNEX(R), the first generation ultrasound contrast agent.

Bobba Venkatadri, president and chief executive officer of Molecular Biosystems, said: "We are very pleased that Mallinckrodt has been able to roll out OPTISON(TM) within 48 hours of approval. Early acceptance by the medical community is a clear indication of its clinical utility."

Muhilly also indicated that ALBUNEX(R) is being repositioned as a tool to diagnose reproductive disorders. The indication is for the diagnosis of fallopian tube patency, which refers to the degree to which the fallopian tube is open or blocked.

MBI, based in San Diego, is a world leader in the development and manufacture of ultrasound contrast agents for medical imaging.

Based in St. Louis, and operating globally in more than 100 countries, Mallinckrodt Inc. had fiscal 1997 net sales of $1.9 billion. The Mallinckrodt web site address is www.mallinckrodt.com. -0-

Note: Molecular Biosystems news releases are available via fax by calling 888-329-4007 toll free. MBI's new web site at http://www.mobi.com provides an informative overview of the company and its products. The web site includes information about MBI's products and development programs, corporate partner and research pipeline. The site also contains investor information, including links to the company's financial information and current stock price.

This news release contains forward-looking statements that involve risk and uncertainties. The commercialization of OPTISON(TM) may differ materially from the company's expectations. Among the factors that could result in a materially different outcome are the following: the failure of the ultrasound contrast agent market to develop consistently with the company's expectations, the failure of ultrasound contrast agents to penetrate expanded markets; an adverse result in MBI's and Mallinckrodt's pending patent lawsuit against, or future litigation with, Sonus Pharmaceutical Inc.; Nycomed Imaging AS; ImaRx Pharmaceutical Corp. and marketing partner DuPont Merck; and Bracco International B.V., including potential injunctive relief delaying or prohibiting the sale of OPTISON(TM); an adverse ruling by the PTO in the pending patent reexaminations; unfavorable results in clinical trials, the ability of the company to obtain FDA approval for the use of OPTISON(TM); to detect myocardial perfusion; the inherent uncertainty involved in the development of any new product; and other risk factors reported from time to time in MBI's filing with the Securities Exchange Commission.

CONTACT: Molecular Biosystems, Inc.

Gerard A. Wills, 619/824-2219

Stephen F. Keane, 619/824-2212

Patricia Sullivan, 619/824-2262

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Mallinckrodt Inc.

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