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Ultrasound Med Biol. 2016 Apr;42(4):956-63. doi: 10.1016/j.ultrasmedbio.2015.12.009. Epub 2016 Jan 21.

Enhancement of Small Molecule Delivery by Pulsed High-Intensity Focused Ultrasound: A Parameter Exploration.

Author information

1
School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
2
Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, Seattle, Washington, USA. Electronic address: ynwang@u.washington.edu.
3
Department of Bioengineering, University of Washington, Seattle, Washington, USA.
4
Division of Gastroenterology, School of Medicine, University of Washington, Seattle, Washington, USA.
5
Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, Missouri, USA.
6
Digestive Disease Center and Research Institute, Department of Internal Medicine, Soonchunhyang University College of Medicine, Asan, Korea.
7
Center for Industrial and Medical Ultrasound, Applied Physics Laboratory, University of Washington, Seattle, Washington, USA; Division of Gastroenterology, School of Medicine, University of Washington, Seattle, Washington, USA.

Abstract

Chemotherapeutic drug delivery is often ineffective within solid tumors, but increasing the drug dose would result in systemic toxicity. The use of high-intensity focused ultrasound (HIFU) has the potential to enhance penetration of small molecules. However, operation parameters need to be optimized before the use of chemotherapeutic drugs in vivo and translation to clinical trials. In this study, the effects of pulsed HIFU (pHIFU) parameters (spatial-average pulse-average intensity, duty factor and pulse repetition frequency) on the penetration as well as content of small molecules were evaluated in ex vivo porcine kidneys. Specific HIFU parameters resulted in more than 40 times greater Evans blue content and 3.5 times the penetration depth compared with untreated samples. When selected parameters were applied to porcine kidneys in vivo, a 2.3-fold increase in concentration was obtained after a 2-min exposure to pHIFU. Pulsed HIFU has been found to be an effective modality to enhance both the concentration and penetration depth of small molecules in tissue using the optimized HIFU parameters. Although, performed in normal tissue, this study has the promise of translation into tumor tissue.

KEYWORDS:

Content and penetration; Drug delivery; Kidney; Pulsed-high intensity focused ultrasound; Ultrasound parameters

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