Ultrasonic drug delivery in Oncology

Ultrasound-assisted drug delivery is an emerging technique that has the advantage of being non-invasive, efficiently and specifically targeted and controllable. While systemic drugs often show detrimental side effects, their ultrasound-triggered local release at the selected tissue may improve safety and specifity of therapy. An increasing amount of animal and preclinical studies demonstrates how ultrasound can also be used for increasing the efficacy of chemotherapeutic drug release to solid tumors. In particular, this technique may be functional to reach uniform delivery of chemotherapeutic agents throughout tumors, which is naturally restricted by their abnormal vascularization and interstitial pressure. This review deals with the physical mechanisms of ultrasound, the different kinds of drug carriers (microbubbles, liposomes and micelles) and the biological phenomena useful for cancer treatment (hyperthermia, sonoporation, enhanced extravasation, sonophoresis and blood-brain barrier disruption), showing how much ultrasonic drug delivery is a promising method in the oncological field.