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.
For people with type 2 diabetes, could the days of having to jab themselves with a needle whenever they need insulin be over?
"We are really hopeful that this new type of capsule could someday help diabetic patients and perhaps anyone who requires therapies that can now only be given by injection or infusion", senior author Dr Robert Langer, a member of MIT's Koch Institute for Integrative Cancer Research said in a press release. It contains a tiny needle made of freeze-dried compressed insulin, which is released and injected into the stomach's lining. The same capsule can also be adapted to deliver other protein drugs.
The team, from Brigham and Women's Hospital and the Massachusetts Institute of Technology, says this localized approach is more pleasant to take, easier to carry around and less expensive than traditional injections. The first author of the paper, which appears in the February 8 issue of Science, is MIT graduate student Alex Abramson.
The capsule system was developed by a team of researchers from MIT, Brigham and Women's Hospital, and insulin manufacturer Novo Nordisk. The material itself is nearly completely made from compressed, freeze-dried insulin.
Since the capsule has only one needle, it has to be able to orient itself to deliver the injection. So, they turned to an unlikely animal for inspiration: the leopard tortoise.
Within the capsule, the needle is attached to a compressed spring that is held in place by a disk made of sugar.
Stomach acid gradually dissolves the sugar until the spring pops, shooting the insulin into the stomach wall. There are no pain receptors in the stomach, so the injection shouldn't hurt, the researchers noted.
"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. This allows it to right itself if it rolls onto its back. The researchers used computer modeling to come up with a variant of this shape for their capsule, which allows it to reorient itself even in the dynamic environment of the stomach.
Diabetes occurs when there are too few beta cells in the pancreas to produce insulin or when they produce very little insulin, the hormone needed to get glucose from the bloodstream into cells.
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.
The metal spring and rest of the capsule passed through the digestive system, without seeming to cause any problems.
The researchers describe the capsule as "about the size of a pea" and made from biodegradable polymer and bits of stainless steel.
"Our motivation is to make it easier for patients to take medication, particularly medications that require an injection", Traverso says.
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.