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, Schoellhammer says.
The researchers tested their new approach using pig skin and found that it boosted permeability much more than a single-frequency system. First, they delivered the ultrasound waves, then applied either glucose or inulin (a carbohydrate) to the treated skin. Glucose was absorbed 10 times better, and inulin four times better. "We think we can increase the enhancement of delivery even more by tweaking a few other things," Schoellhammer says.
Noninvasive drug delivery
Such a system could be used to deliver any type of drug that is currently given by capsule, potentially increasing the dosage that can be administered. It could also be used to deliver drugs for skin conditions such as acne or psoriasis, or to enhance the activity of transdermal patches already in use, such as nicotine patches.
Ultrasound transdermal drug delivery could also offer a noninvasive way for diabetics to control their blood sugar levels, through short- or long-term delivery of insulin, the researchers say. Following ultrasound treatment, improved permeability can last up to 24 hours, allowing for delivery of insulin or other drugs over an extended period of time.
Such devices also hold potential for administering vaccines, according
|Contact: Sarah McDonnell|
Massachusetts Institute of Technology