If there is anything more difficult for diabetics than the lifestyle restrictions, it is perhaps the painful insulin shots. An ingestible insulin has eluded drug makers primarily because of its chemical structure — insulin is a protein and tends to be broken down by protein-digesting enzymes in the gut before it can enter the bloodstream and start its action.
Researchers from Harvard University have now devised a way to deliver insulin through the gut by wrapping it in a coating that resists its breakdown by gastric juices. This could be the first step in delivering insulin in ways other than an injection or via pump.
The product would have to undergo clinical trials to see if it makes the cut as a therapeutic intervention that is efficacious and free of side effects. In an article in the Proceedings of the National Academy of Sciences, researchers described the new approach to carry insulin in an ionic liquid comprising choline and geranic acid (a biological compound that acts as a pheromone in some animals). This liquid is then put inside a capsule with an acid-resistant enteric coating. This is important because the environment of the gut is acidic.
India, which is touted as the diabetes capital of the world, has an estimated 70 million people living with diabetes. For many of them the underlying cause is the inability of the body to produce insulin. Insulin has to be supplied externally for the body to metabolise sugars but the injection is often the reason for poor patient compliance.
“When a protein molecule, such as insulin enters the intestine, there are many enzymes whose function is to degrade the proteins into smaller amino acids. But the ionic liquid-borne insulin remains stable,” said first author Amrita Banerjee, who conducted the research while working as a postdoctoral fellow and is now an assistant professor at North Dakota State University.
In the article about the “development of a highly effective oral insulin formulation using choline and geranate (CAGE) ionic liquid”, the Harvard researchers said: “When 10 U/kg insulin-CAGE was orally delivered in enterically coated capsules…a sustained decrease in blood glucose of up to 45% was observed. The formulation exhibited high biocompatibility and was stable for two months at room temperature and for at least four months under refrigeration.”