In an ideal world, managing diabetes wouldn’t involve insulin injections but would be as simple as popping a pill. Now a team of scientists has demonstrated an oral tablet that’s self-propelled by chemical “micromotors” to deliver insulin in the colon of rats.
People living with diabetes have to carefully manage their glucose levels, usually by periodically administering insulin injections. An oral pill would be much simpler, of course, but unfortunately insulin is a fragile molecule that breaks down in the stomach acid before it reaches the intestines to be absorbed into the bloodstream.
Oral insulin has long been a key goal for scientists, with some formulations in the advanced stages of human clinical trials. Recent work has explored ways to encapsulate the hormone in protective coatings to survive the extreme environment of the stomach, but once it reaches the intestines the insulin still diffuses passively through the membrane into the bloodstream, which isn’t the most efficient method.
Other studies have attempted to get around this problem with nanoparticles that get into the bloodstream and only release insulin when glucose levels rise, capsules with microneedles that directly inject insulin into the stomach lining, or robotic capsules that burrow into the intestinal lining.
For the new study, scientists in China have developed an oral pill that not only ferries insulin safely to the colon, but once there takes an active role in digging into the intestinal wall. That’s thanks to what the team calls chemical micromotors that propel the pill.
The 3-mm-long pills contain magnesium microparticles, with a solution containing insulin and a layer of liposomes, mixed with baking soda and finally coated in an esterified starch solution. Each of these ingredients has a special role to play.
The starch protects the tablets as they make their way through the stomach to the colon. Once there, the tablets break down until the microparticles are exposed, allowing the magnesium to react with water to produce a stream of hydrogen gas bubbles. This propels the pill towards the lining of the colon, where it can be absorbed more efficiently.
In tests in rats, the team found that these oral insulin pills could significantly reduce the glucose levels in the animals’ bloodstreams for more than five hours. The levels maintained were almost as low as those where insulin is delivered via injection.
While there’s still plenty of work left to be done, the team says that this system is not only a step towards oral insulin pills, but could be used to make oral forms of other medications traditionally delivered through injection.
The research was published in the journal ACS Nano.
Source: American Chemical Society
