April 23, 2008 -- The elusive insulin pill appears to have received a shot in the arm.
Whispers of an insulin pill have been around for years, but efforts to develop one have been hampered by the body's own digestive process. The stomach acids needed to break down foods also destroy the hormone insulin. Research groups worldwide have been experimenting with ways around this obstacle; however, an ideal material for safe, effective delivery by mouth has remained out of reach.
Now, researchers in Texas say a novel gel-like material could help speed up the widely anticipated arrival of oral insulin, renewing hopes for the millions of Americas with diabetes who must have daily insulin shots to tame their diabetes.
In the April 14 issue of Biomacromolecules, researchers report on a promising new delivery system candidate in the form of a gel-like substance called a polymer hydrogel, which responds to changes in pH levels between the stomach and small intestine. The gel contains a type of sticky plant molecule called wheat germ agglutinin (WGA).
For the experiment, Kristy Wood, PhD, and colleagues at the University of Texas at Austin loaded insulin onto polymer hydrogel microparticles. Their laboratory tests showed that the hydrogel carriers safely usher insulin into the stomach, where they expand to protect the drug from the harsh acidic environment. When the delivery pods reach the less acidic small intestine the gel shrinks and releases the insulin to be absorbed.
The study authors say their research demonstrates that the WGA technique allows for the quick release of insulin in the small intestines and improves the duration of insulin absorption. "In addition, results of this experiment show that the change in pH between the stomach and the small intestine can be used as a physiologic trigger to release insulin from the hydrogel microparticles," they write in the journal article.
The authors concluded that the method "shows great promise as an oral insulin delivery system." However, it is important to note that these experiments were performed in a laboratory dish. It could be many years before the technique is perfected and approved for use in humans.