Delivery of drugs with ultrasound.

In this article we discuss the potential role of microbubbles, traditionally used as ultrasound contrast agents, for site-specific drug delivery. To reach this goal, microbubbles capable of carrying a drug payload are being developed. To ensure that these microbubbles reach sufficient local concentration at disease sites, specific targeting for diseased tissues can be accomplished using several strategies. These strategies rely on either the intrinsic properties of microbubble shells or conjugation of monoclonal antibodies or other ligands to these shells that recognize antigens expressed in regions of disease. Site-specific delivery of antiinflammatory, antineoplastic, and thrombolytic drugs with microbubbles can be further enhanced by the ability to locally destroy microbubbles within an acoustic field, thereby releasing drugs and improving drug efficacy without systemic adverse effects. In the case of thrombi, ultrasound-mediated microbubble destruction also may facilitate the process of clot lysis. This review also will consider current limitations and technological advances required for the development of this field.