Researchers at MIT have made it possible to enhance skin permeability using ultrasound waves. The technology seems promising for future transdermal drug delivery without the need of using needles. The research results were published in the Journal of Controlled Release.
This new technology makes use of ultrasound waves with two different frequencies that generate small bubbles of water on the surface of the skin. When these bubbles pop, it makes the skin more permeable, allowing drugs to penetrate more easily through the skin. The new technique was tested on pig skin, in which it showed a 10 times better glucose absorption and a 4 times better insulin absorption.
The ultrasound treatment could improve skin permeability for up to 24 hours. It holds promise for the future non-invasive delivery of drugs that are currently administered by needle or by capsule. It can also make transdermal patches more effective. Vaccination can become needle-free as well. The research group will continue their efforts, developing a handheld ultrasound, and finding ways to further enhance permeability before commencing with the first tests on human skin.
The principle is described more precisely from an MIT press release::
When ultrasound waves travel through a fluid, they create tiny bubbles that move chaotically. Once the bubbles reach a certain size, they become unstable and implode. Surrounding fluid rushes into the empty space, generating high-speed “microjets” of fluid that create microscopic abrasions on the skin. In this case, the fluid could be water or a liquid containing the drug to be delivered.
In recent years, researchers working to enhance transdermal drug delivery have focused on low-frequency ultrasound, because the high-frequency waves don’t have enough energy to make the bubbles pop. However, those systems usually produce abrasions in scattered, random spots across the treated area.
In the new study, the MIT team found that combining high and low frequencies offers better results. The high-frequency ultrasound waves generate additional bubbles, which are popped by the low-frequency waves. The high-frequency ultrasound waves also limit the lateral movement of the bubbles, keeping them contained in the desired treatment area and creating more uniform abrasion
Press release on MIT website: Getting (drugs) under your skin
Article in the Journal of Controlled Release: Rapid skin permeabilization by the simultaneous application of dual-frequency, high-intensity ultrasound