If you've got a big protein molecule like insulin, right now the only option for getting it into your body is via a needle or cannula into the subcutaneous tissue. It can't be swallowed because the digestive system would, logically enough, digest it.

Regular skin patches, like those for estrogen and nicotine, send small molecules through the pores. But they never worked for insulin because the strapping molecule was too big to fit through skin pores. At least until now.

Encapsulation Systems, Inc., believes they have found a way to make the insulin molecules squeeze through your pores into the blood stream. They have invented a battery-powered ultrasonic device, called the U-Strip, to enlarge sweat and hair follicle pores, making them big enough to allow the passage of insulin through the skin. The device uses transducers (which transform one type of energy into another) to produce the ultrasound that enlarges the pores.

A little array of four transducers is strapped on top of a transdermal patch that contains insulin. All at once or sequentially, depending on how large a dose you want, they emanate ultrasonic waves that enlarge the pores around a hair follicle to about twice their normal size.

Then the insulin is wicked down the hair follicle to the hair root, and from there into the blood stream. Sweat pores are also enlarged, so that insulin is deposited into the dermis, from whence it slowly seeps into the bloodstream over time.

After the transducers prime the skin and enlarge the pores enough to permit the passage of large molecules, the ultrasound pushes the insulin out of the patch and through the skin. The use of an array of four transducers keeps any one transport site on the skin from being overused and allows for larger dosages by using more than one at a time.

The patch, which is designed to last for three days, holds from 20 to 100 units of insulin, and it's programmable, so it can provide a basal dose from 0.25 to 1 unit per hour. It's even capable of giving a bolus dose of up to eight units in thirty minutes. And it has a sixty-day memory and a download feature.

In clinical tests on people with type 2 diabetes, the U-Strip provided glucose reductions comparable to an insulin pump. Furthermore, it maintained patients in the normal glucose range throughout the day. During another trial on 25 type 2s, the subjects did not hear the ultrasonic device or feel any discomfort or heat. There was no noticeable damage to their skin after 120 continuous minutes.

Unfortunately, the patch has not yet been approved by the FDA. It's still in Phase 2 clinical trials. But Encapsulation Systems, Inc., is optimistic. Let's hope their optimism is well-founded.