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Electric pulses pour drugs through skin.

The skin's outer surface -- a layer of dead, flattened cells -- provides a barrier to microbes, chemicals, and other potentially toxic agents. But at times physicians would like to breach that barrier, because administering drugs through the skin potentially offers several therapeutic advantages.

Now, researchers at the Massachusetts Institute of Technology have come up with a novel approach for temporarily increasing the permeability of skin. They administer a series of very short, up-to-100-volt pulses of electric current. The resulting rearrangement of fatty layers in the dead, outer skin appears to create temporary pores, or channels, explains Robert Langer.

Using fluorescent dyes to represent drugs, Langer's team delivered millisecond pulses of current every 5 seconds for an hour and monitored the dyes' passage through skin. Some tests used skin from human cadvers; others involved live rats. In the Nov. 15 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES, Langer's group reports that the technique, electroporation, achieved a reversible, 1,000-fold increase in skin permeability.

The idea of using an electric current to pass drugs through the skin is not new. It forms the basis of iontophoresis -- a process that "uses very low voltages for very long periods to drive a charged molecule [such as a drug] through a barrier," notes Langer. Electroporation, by contrast, not only employs much higher voltages for far shorter periods of time, but also works on the barrier -- here, the skin -- not on the drug.

Langer emphasizes that before the technique can find use in drug delivery, many nagging questions must be answered, including how safe and effective it would be for long--term use.

A lack of imaging data to confirm mechanistically what's happening to the skin surface leaves open the question of whether Langer's team achieved electroporation -- at least in the classic sense -- says Bruce M. Chassy. A microbiologist at the University of Illinois at Urgana-Champaign, Chassy uses electroporation to move materials into bacteria.

However, he adds, "whether it's electroporation is not really important" -- as long as the technique delivers a drug without permanently damaging the skin. Indeed, he described the new MIT results as "exciting." In fact, he said, it may possess as much potential to transport samples out of the body -- perhaps for noninvasive blood sampling--as it has to move small samples inside.
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Title Annotation:increasing skin permeability by rearranging fatty layers of skin through electric pulses
Author:Raloff, Janet
Publication:Science News
Article Type:Brief Article
Date:Nov 20, 1993
Words:377
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