The biggest problem that insulin-dependent diabetics have with treating their condition is the number of needle sticks they have to do each day.
To try to meet this challenge, the researchers developed a capsule that contains a small needle that's made of compressed insulin. These people have to check blood sugar levels, which requires a finger prick, and then have to inject insulin via a syringe as needed. The same capsule can also be adapted to deliver other protein drugs.
Giovanni Traverso, an assistant professor at Brigham and Women's Hospital, Harvard Medical School, and a visiting scientist in MIT's Department of Mechanical Engineering, where he is starting as a faculty member in 2019, is also a senior author of the study. The first author of the paper, which appears in the February 8 issue of Science, is MIT graduate student Alex Abramson. MIT teamed up with pharmaceutical company Norvo Nordisk for the research. The material itself is nearly completely made from compressed, freeze-dried insulin.
The needle is spring-loaded - it is attached to a tiny compressed spring that's held in place by sugar. There are no pain receptors in the stomach, so the injection shouldn't hurt, the researchers noted. Therefore, the researchers needed to ensure that their little insulin needles would only inject into the wall of the stomach, rather than randomly be released.
"Instead of liquid, we wanted to make it solid because you can fit a lot more in the pill in solid form than in liquid", said Dr Traverso.
The researchers drew their inspiration for the self-orientation feature from a tortoise known as the leopard tortoise. This allows it to right itself if it rolls onto its back. There is no indication of when the capsule might come to the commercial market.
Once the tip of the needle is injected into the stomach wall, the insulin dissolves at a rate that can be controlled by the researchers as the capsule is prepared.
Tests in pigs have shown the device is able to successfully deliver insulin in the same quantities that people with type 2 diabetes would typically take.
In recent tests, this dose was increased to five milligrams, which is approximately the amount a patient with type 2 diabetes needs to inject.
Once the insulin was absorbed, the capsule, made of stainless steel and a biodegradable material, floated free and was excreted.
"Our motivation is to make it easier for patients to take medication, particularly medications that require an injection", Traverso says.
Patients usually prefer oral treatment, and comply with it better, but many compounds, including insulin for diabetes, can't survive the harsh trip through the digestive system.
Other authors of the paper include Ester Caffarel-Salvador, Minsoo Khang, David Dellal, David Silverstein, Yuan Gao, Morten Revsgaard Frederiksen, Andreas Vegge, Frantisek Hubalek, Jorrit Water, Anders Friderichsen, Johannes Fels, Rikke Kaae Kirk, Cody Cleveland, Joy Collins, Siddartha Tamang, Alison Hayward, Tomas Landh, Stephen Buckley, Niclas Roxhed, and Ulrik Rahbek.