Of the hundreds of million people around the world that suffer from diabetes, a sizeable portion need to subject themselves to daily insulin injections. But a more palatable way of keeping blood glucose levels in check may be on the way, with scientists developing a patch that attaches to the intestinal wall and releases the hormone after being swallowed in the form of a capsule.
As most would rather wash a pill down with a glass of water than inject themselves on a regular basis, scientists around the world have been pursuing an effective approach to administering insulin orally for years. Primarily, the problem lies in the hormone's susceptibility to the digestive enzymes in the gastrointestinal tract, which cause it to break down when swallowed before it can carry out its purpose.
Some efforts to overcome this have sought to carry the insulin inside liposomes or nanoparticles, preventing it from destruction before it can be absorbed by the body. It is this line of thinking that inspired scientists at the University of California, Santa Barbara, to produce a new kind of insulin-loaded patch made from mucoadhesive polymers, which would be carried through the body inside a protective shell.
By treating the patch with an intestinal permeation enhancer and placing it inside a capsule with an enteric coating (a polymer barrier to protect from acidity of stomach), the researchers found themselves with a pill designed to dissolve and release its payload at just the right time. Once set free, the patches are intended to attach to the intestinal wall for an accurate and more effective delivery of insulin.
The researchers tested both the adhesive strength of the patch, which involved measuring the force required to peel the patch off the intestinal wall after 30 minutes, and the release of drugs on rat and pig intestines. They describe the stickiness of the patch as excellent, and say it released 100 percent of the insulin and permeation enhancer within five hours.
After testing various concentrations, they found insulin patches containing 10 percent permeation enhancer to be the most effective, causing glood glucose levels to drop to around 70 percent of normal levels compared to the control group receiving no treatment.
The scientists will now continue their research, using rats to work towards intestinal patches that allow for faster or prolonged release of insulin.
The work was presented on October 27 at the 2015 American Association of Pharmaceutical Scientists (AAPS) Annual Meeting and Exposition.
