Basic properties and results of clinical trials of ultrasound contrast agents based on galactose

The development of reproducible echogenic contrast agents, which contain physiologically degradable acoustic strays in micrometre dimensions, has been under way for several years; all currently known industrial echocontrast agents are based on microbubbles, due to their special acoustic properties. The currently known echogenic contrast agents can be divided into three physically different types: microbubble-containing liquids, gas-filled microspheres and microbubble-containing suspensions (e.g. SH U 454-Echovist and SH U 508 A). The agents SH U 454 and SH U 508 A are based on galactose microparticles, which are suspended shortly before use. After intravenous injection, SH U 454 dissolves after leaving the right heart before the left heart is reached. SH U 508 A displays greater intravascular stability than SH U 454 and leads to an increase of the echogenicity in the blood which, after intravenous injection, survives pulmonary transit and reaches the arterial vascular bed. This indicates that the microbubbles are stable under physiological pressures. After intravascular dissolution of the microstructures, the remaining galactose (a monosaccharide with no known allergenic potential) is degraded physiologically. To date, a total of more than 2,500 patients has been examined in clinical trials with SH U 454 (Echovist). The intravenous administration of this contrast agent was well tolerated; in particular, no substance-induced severe adverse events were observed, and no clinically relevant changes of cardiovascular function or of laboratory parameters occurred. Extensive clinical experience has been gained in the main indications echocardiography (> 1,850 patients), venous vessels (> 200 patients) and hysterosalpingocontrast sonography (> 500 patients).(ABSTRACT TRUNCATED AT 250 WORDS)