Sonus Pharmaceuticals Inc. has competed a Phase I trial of EchoGen,its ultrasound imaging agent that could eventually compete withMolecular Biosystems Inc's Albunex, the only such agent to receiveFDA approval.Sonus is developing EchoGen as an imaging agent for the diagnosis ofcardiac disease, cancer and other conditions. The Phase I trial in 25healthy male subjects demonstrated safety, rapid clearance of the drugfrom the body and diagnostic usefulness of the product in cardiologyand radiology applications.Gail Hall, director of marketing for the Bothell, Wash., company, saidSonus has also filed applications with the FDA for an additional PhaseI exercise-stress echocardiology study for myocardial perfusion, andfor two Phase II trials. One would study the effects of EchoGen inother cardiac indications. The other would focus on radiologicalapplications.Sonus's drug is intended to assess heart-wall motion and myocardialperfusion, and to detect space-filling lesions in abdominal organs. Assuch, it would compete with a second-generation version of Albunexthat Molecular Biosystems, of San Diego, is already developing.EchoGen is designed for use at diagnosis, during treatments such asballoon-angioplasty, and for ongoing cardiac monitoring.Sonus's PhaseShift technology uses a special emulsion,dodecofluoropentane, that undergoes a phase change from a liquid to agas when injected into the bloodstream. The liquid emulsion containssubmicron-size particles that expand to become microbubbles when thephase shift occurs. The technology takes advantage of the emulsion'sability to boil at temperatures lower than the body's, forming uniformgas bubbles that remain stable and undissolved in the body for aspecified time. In the bloodstream or other fluid compartments, theemulsion is able to greatly reflect sound.Dodecofluoropentane was selected on the basis of its "Q-factor," a termSonus intends to patent. A Q-factor of one represents the length of timea gas remains undissolved as a microbubble compared to air.Dodecofluoropentane's Q-factor of more than 10,000 indicated that itcould remain undissolved in the body for more than five minutes.Sonus is developing other contrast agents for imaging soft tissues suchas the breast and prostate and for detecting vascular lesions of thecentral nervous system. The company's contrast agents are beingdesigned to enhance the system's sensitivity to the Doppler signal inorgans as a way to measure real-time regional blood flow withinorgans.
-- Philippa Maister
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