Physicochemical Characteristics of Sonazoid™, A New Contrast Agent for Ultrasound Imaging

The objective of the current work is to describe the physicochemical characteristics of Sonazoid™, a new ultrasound contrast agent for detection and characterisation of focal liver lesions. It has been demonstrated that Sonazoid™ powder for injection consists of microspheres of perfluorobutane (PFB) stabilised by a monomolecular membrane of hydrogenated egg phosphatidyl serine, embedded in an amorphous sucrose structure. Upon reconstitution with sterile water, stabilised microspheres of PFB are released in a predefined amount and size into a low viscosity, isotonic sucrose solution with a neutral pH. Sonazoid™ reconstituted product contains approximately 8 μl microspheres/ml with volume median diameter of approximately 2.6 μm. The product contains approximately 1.2 billion microspheres/ml of which less than 0.1% are larger than 7 μm. The acoustic properties of Sonazoid™ such as attenuation efficacy, fundamental and second harmonic backscatter efficacy are all well correlated to the microsphere volume concentration. The stability of Sonazoid™ after reconstitution is good, with no significant changes in physicochemical properties 2 h after reconstitution. Pressure stress is well tolerated by both concentrated and diluted Sonazoid™ with no permanent effects of pressures up to 300 mm Hg. The level and consistency of the investigated physicochemical properties demonstrate that Sonazoid™ should be well suited as a contrast agent for medical imaging with ultrasound. (E-mail: per.sontum@ge.com)