Ultrasonic Drug Delivery

Treating diseases in the brain is challenging because its natural armour – the blood-brain barrier – prevents not only pathogens and toxins from entering, but also drugs. In search of non-surgical options for accessing the brain, researchers have discovered that targeted ultrasound combined with gas-filled microbubbles can briefly and safely open the barrier. The bubbles are intravenously injected along with the drug and the ultrasound beams are then focussed at the site to be treated. The sound waves agitate the bubbles in the region, disrupting the normally impenetrable vessel walls (the barrier) and allowing the drug to pass through. Already tested in animals, the technique is now in small-scale human trials, like the one that included this brain cancer patient. The right-hand image shows entry of the drug into the brain tumour (arrow) following targeted ultrasound, while the left-hand image shows almost no drug uptake when ultrasound was not applied.

Written by Ruth Williams

Ruth Williams

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Ruth is a freelance science journalist based in the US. She's a regular correspondent for The Scientist, and her work has appeared in The Lancet, Nature, Scientific American Mind, BBC Focus and elsewhere. Twitter @rooph

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• Image from work by Ying Meng and colleagues
• Sunnybrook Research Institute, Harquail Centre for Neuromodulation, Toronto, ON, Canada
• Image copyright held by the original authors
• Research published in Science Translational Medicine, October 2021