albumin microspheres

Albunex is an ultrasound contrast agent composed of air-filled human serum albumin microspheres. Developed by Molecular Biosystems and approved by the FDA in 1994, it was the first commercially available transpulmonary contrast agent for echocardiography. The microspheres, typically 3 to 5 micrometers in diameter, are created by sonicating a 5% human serum albumin solution, which encapsulates air bubbles within a stable protein shell. When injected intravenously, these microspheres are small enough to pass through the pulmonary vasculature and enter the left heart, where they enhance the backscatter of ultrasound waves. This improves the opacification of the left ventricular chamber and the definition of the endocardial border, aiding in the assessment of cardiac structures and function. While it established the field of contrast echocardiography, it has largely been superseded by second-generation agents with greater stability and longer-lasting contrast effects, such as Optison (perflutren).

Brand names

Albunex

Other names

Albumin Microspheres (Human)Sonicated AlbuminAir-filled albumin microspheres