When a pill is swallowed, it embarks on a perilous journey before it can be absorbed into the body. Even if it manages to survive exposure to stomach acid and resist degradation by digestive enzymes, the pill must then penetrate the mucus barrier—the gut’s defense against unwelcome particles.
Some large-protein drugs, including the diabetes-treating insulin and the antibiotic vancomycin, can’t pass through the mucus barrier at all. Because of the barrier’s strength, less than 1 percent of insulin taken orally is absorbed and used by the body, requiring patients to inject it instead.
But in a new study published in Science Robotics last week, researchers created a robotic pill that can drill through the mucus barrier to deliver drugs more efficiently.
“I was watching videos of these machines that can make tunnels,” Shriya Srinivasan, a biomedical engineer at MIT and lead author of the study, tells New Scientist’s Alex Wilkins. “I thought, ‘OK, what if we did this but for mucus.”
The team’s robotic pill, called RoboCap, is about the size of a multivitamin. Inside, it holds the drug payload in a tiny compartment. The outside is grooved, studded and coated in a gelatin that dissolves at a certain pH. When the pill is swallowed and reaches the stomach, the acidity erodes away the coating. Then, the small intestine’s pH triggers a motor inside the capsule that makes the pill begin spinning.
The device’s textured surface clears away the mucus, and the rotating motion erodes the compartment with the drug payload, which slowly releases into the digestive tract. After about 35 minutes of activity, the capsule moves through the rest of the tract normally and exits the body with a bowel movement.
The researchers tested the pill’s ability to deliver insulin and vancomycin in excised pig small intestine tissue and in seven live pigs. Compared to a similar pill without the spinning mechanism, RoboCap increased the amount of drug absorbed by 20 to 40 times, per the study.
In the live pig insulin tests, the pill worked so well that one hour after delivery, three of the animals became hypoglycemic as a result of the drug. The researchers had to administer dextrose to increase the pigs’ blood sugar levels.
“This substantiates its significant potential to enable oral delivery of molecules that have previously seen little success by oral administration,” the authors write in the paper. “Future studies in swine and humans should optimize the dosage for such drugs to identify the therapeutic ranges via SI [small intestinal] delivery.”
RoboCap could help patients avoid daily shots or stop them from having to go to a hospital to receive medications, which could be “a huge game changer,” Srinivasan tells Science News’ Meghan Rosen.
Further research should look at how the pill would affect people with weakened immune systems, as well as how it impacts helpful bacteria living in the gut’s mucus, says Abdul Basit, a pharmaceutics researcher at University College London in England who was not involved with the study, to New Scientist.
“RoboCap is an innovative concept that aims to overcome the current difficulty in orally delivering many advanced and emerging therapies," he adds.