No more injections- New pill developed to deliver oral doses of insulin
A researchers' team from Massachusetts Institute of Technology has developed a drug capsule which could probably replace injectable insulin that type 2 diabetes patients have to take on a regular basis. This drug, not bigger than a blueberry, contains a small needle made of compressed insulin, which is injected as it reaches the stomach. The study was published in 8 issue of Science.
In tests in animals, the researchers showed that they could deliver enough insulin to lower blood sugar to levels comparable to those produced by injections given through skin. They also demonstrated that the device can be adapted to deliver other protein drugs.
"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," says Robert Langer, the David H. Koch Institute Professor, a member of MIT's Koch Institute for Integrative Cancer Research, and one of the senior authors of the study.
The drug has the following characteristics which makes it a reliable alternative for diabetic patients.
Several years ago, Traverso, Langer, and their colleagues developed a pill coated with many tiny needles that could be used to inject drugs into the lining of the stomach or the small intestine. For the new capsule, the researchers changed the design to have just one needle, allowing them to avoid injecting drugs into the interior of the stomach, where they would be broken down by stomach acids before having any effect.
The tip of the needle is made of nearly 100 per cent compressed, freeze-dried insulin, using the same process used to form tablets of medicine. The shaft of the needle, which does not enter the stomach wall, is made from another biodegradable material.
Within the capsule, the needle is attached to a compressed spring that is held in place by a disk made of sugar. When the capsule is swallowed, water in the stomach dissolves the sugar disk, releasing the spring and injecting the needle into the stomach wall.
The stomach wall has no pain receptors, so the researchers believe that patients would not be able to feel the injection. To ensure that the drug is injected into the stomach wall, the researchers designed their system so that no matter how the capsule lands in the stomach, it can orient itself so the needle is in contact with the lining of the stomach.
"As soon as you take it, you want the system to self-right so that you can ensure contact with the tissue," Traverso says.
The researchers drew their inspiration for the self-orientation feature from a tortoise known as the leopard tortoise. This tortoise, which is found in Africa, has a shell with a high, steep dome, allowing it to right itself if it rolls onto its back. The researchers used computer modelling 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.
"What's important is that we have the needle in contact with the tissue when it is injected," Abramson says. "Also, if a person were to move around or the stomach was to growl, the device would not move from its preferred orientation."
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. In this study, it took about an hour for all of the insulin to be fully released into the bloodstream.
Easier for patients
In tests in pigs, the researchers showed that they could successfully deliver up to 300 micrograms of insulin. More recently, they have been able to increase the dose to 5 milligrams, which is comparable to the amount that a patient with type 2 diabetes would need to inject.
After the capsule releases its contents, it can pass harmlessly through the digestive system. The researchers found no adverse effects from the capsule, which is made from biodegradable polymer and stainless steel components.
"Our motivation is to make it easier for patients to take medication, particularly medications that require an injection," Traverso says. "The classic one is insulin, but there are many others."