Method for ultrasound triggered drug delivery using hollow microbubbles with controlled fragility

Abstract

A method is provided for site specific delivering therapeutic or diagnostic agents to a region in a fluid-filled cavity, vessel or tissue using an agent-loaded microbubble population. The population has controlled fragility characterized by a uniform wall thickness to diameter ratio which defines the discrete threshold intensity value of ultrasonic power where microbubble rupture occurs in the population. The location of the microbubble population may be monitored by ultrasound to determine its presence at the region prior to application of the ultrasonic power to rupture to microbubbles.

1 . A method of site-specific delivery of therapeutic or diagnostic agent to a region of interest within a fluid-filled cavity, vessel, or fluid perfused tissue by ultrasound comprising the steps of: 
 a. introducing an agent-loaded microbubble population into said region of interest, said microbubble population having a controlled fragility characterized by a wall thickness to diameter ratio that defines a threshold power intensity value of ultrasonic energy where microbubble rupture occurs in the population,    b. applying an ultrasonic signal to the region of interest at a power intensity sufficient to induce microbubble rupture,    c. maintaining said power intensity until at least a substantial number of microbubbles are ruptured.