SONUS Pharmaceuticals, Inc., is engaged in the research and development of ultrasound contrast agents (USCA) and drug delivery systems for use in the diagnosis and treatment of heart disease, cancer and other conditions.
Sonus Pharmaceuticals and OncoGenex Technologies Inc., a privately held biopharmaceutical development company, announced 2008 the signing of a definitive agreement to merge the two companies. The combined company will operate as OncoGenex Pharmaceuticals, Inc.

Ultrasound Contrast Agents:

EchoGen® is a fluorocarbon-based (dodecafluoropentane) third generation USCA. EchoGen® consists of microbubbles stabilized with surfactants in a phase shift colloid emulsion (perflenapent). EchoGen® requires no preparation, reconstitution, or refrigeration.
Perflenapent emulsion would represent a significant advance in contrast echocardiography caused by effective and long lasting opacification of the left ventricle and enhanced endocardial border delineation.
The persistence of the contrast effect permits interrogation in multiple echocardiographic views, as well as the visualization and localization of myocardial perfusion deficits at rest by producing a negative contrast effect.
October 12, 2000
Sonus Pharmaceuticals, Inc. announced a strategic decision to refocus the Company on the development of its drug delivery and blood substitute products. At the same time, Sonus has withdrawn the NDA (New Drug Application) and discontinued clinical activity for its ultrasound contrast product, EchoGen®.
August 06, 2001
Sonus Pharmaceuticals, Inc. announced that it has entered into an agreement to sell its ultrasound contrast assets for $6.5 million to Amersham plc. As part of the agreement, Sonus has also assigned to Nycomed its interest in the ultrasound contrast patent license agreement entered into with Chugai Pharmaceutical Co. Ltd. and Molecular Biosystems Inc in January 2001.

From Sonus Pharmaceuticals
QW7437 (SonoGen) is a perfluorocarbon-based ultrasound contrast agent under development. This anionically charge-stabilized emulsion, similar to EchoGen, has been designed for echocardiographic examinations with greater safety and efficacy.

SonoGen (QW7437) is an anionically charged 2% perfluorocarbon emulsion under development as a transpulmonary myocardial ultrasound contrast agent (UCA). The SonoGen microbubbles have a reduced adherence to the negatively charged vascular endothelium and reduced coalescence. SonoGen, a second generation USCA has the theoretical potential to provide high safety and efficacy and improved tissue grayscale persistence compared to first generation fluorocarbon contrast agents.