Insulin pill for diabetics

CHEMICAL ENGINEERS are getting closer to developing a method for taking insulin and other medications orally instead of by injection.

Purdue University researchers, in findings to be discussed during a national meeting of the American Chemical Society, have demonstrated that the method works in a chemical environment that mimics the stomach and upper small intestine.

The method might be used to treat insulin-dependent diabetes and other conditions for which medicines, such as insulin, currently cannot be administered orally because they are broken down in the acidic environment of the stomach.

To get around this complication, the engineers have made microscopic particles for drug delivery about a millionth of a meter in diameter, or roughly one-hundredth the width of a human hair.

The particles protect medicines from the harsh environment of the stomach until they can be released in the intestines and absorbed into the blood.

In the most recent lab experiments, and in animal research, when the particles enter the less-acidic environment of the upper small intestine they expand and use chemical tethers to latch onto``mucosal''areas and cells that line the intestine.

The tethers serve two roles: They help prevent stomach enzymes from breaking down the particles.

And once the particles enter the intestines, the tethers keep the particles anchored long enough for the medication to be released into the upper small intestine, where the medication is absorbed by capillaries into the blood.

``If we don't have these `anchors' to stick in the upper small intestine and hold the particles for a little while, they will pass through and the medication will never release in the upper small intestine,''said Nicholas A. Peppas, Purdue's Showalter Distinguished Professor of Chemical and Biomedical Engineering.

Aaron Foss, a Purdue doctoral student working with Peppas, said it's important to note that the particles would be flushed out naturally by the body's digestive system after releasing their medication.``The mucosa in the gastrointestinal tract washes out every six to 10 hours,''Foss said.

``If the particles do permanently anchor to the mucosal lining, the mucosa gets washed out, so there is no permanent effect there.``This washing out is important because we don't want to have a buildup of material.''

That would be enough time for them to pass from the stomach into the intestines.

Then, when the acidity was decreased to a level comparable to the upper small intestine's, the particles expanded, enabling the insulin to escape.

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