Acusphere’s AI-700 agent enters phase II trials

Ultrasound contrast agent developer Acusphere of Cambridge, MA, has begun phase II clinical trials of its third-generation agent for assessing myocardial perfusion in patients with coronary artery disease (CAD). The company’s phase II trial will evaluate the best imaging conditions for the assessment of myocardial perfusion in patients with CAD after a single dose of AI-700. Acusphere hopes that AI-700 could offer clinicians a low-cost alternative to nuclear medicine perfusion scans.

First-generation agents last for about a minute when illuminating the endocardium within the ventricles of the heart. Second-generation technology provides four or five minutes of continuous imaging in this application. Ultrasound contrast developers such as Acusphere hope that third-generation agents will extend imaging time to 20 to 30 minutes, or about the time of a cardiac ultrasound examination (SCAN 6/23/99).

Studies have suggested that AI-700 could be used in a continuous mode, allowing clinicians to overcome some of the shortcomings of other agents, which have short persistence times because their contrast-enhancing microbubbles break up under ultrasound beams, according to the company (SCAN 4/14/99). Acusphere believes that the AI-700 microbubbles may have longer persistence times because they are made from synthetic polymers.