The present invention provides a catheter and catheter assembly for delivering micronized therapeutic agents to a target site in the body and, in particular, to a target site in the heart. The micronized therapeutic agents are delivered in aerosol form or dry powder form. The present invention also provides a method of delivering micronized therapeutic agents to a target site in the body by placing the therapeutic agents in a catheter, positioning the catheter in the target site, and exposing the therapeutic agents to an energizing mechanism sufficient to create supersonic flow to carry the therapeutic agents from a stationary state in the catheter to a mobile state towards the target site.