A pill that gives injections
Many medications, especially those consisting of proteins, cannot be taken orally, because they are destroyed in the gastrointestinal tract before they can have their effect. One of these drugs is insulin, which patients with diabetes have to be injected daily and even more often.
To create an alternative to injections, engineers at the Massachusetts Institute of Technology have developed a capsule with a drug that can deliver insulin or other protein preparations, protecting against the aggressive environment of the stomach and other parts of the gastrointestinal tract. When the capsule reaches the small intestine, it breaks down, exposing soluble microneedles that attach to the intestinal wall and release the drug for absorption into the bloodstream.
In tests on pigs, researchers have shown that this capsule can carry an amount of medicine comparable to an insulin injection and provides rapid absorption into the bloodstream immediately after the release of microneedles.
Microneedle delivery
This group of researchers has previously developed several new strategies for oral drug delivery, which should normally be injected. The most famous are a capsule covered with many small needles, as well as star-shaped structures that open and, releasing the drug, can remain in the stomach for several days to several weeks.
Earlier this year, they developed a capsule containing a small needle and compressed insulin: after reaching the stomach, the needle injects the medicine into the mucous membrane. In a new study, scientists decided to develop a capsule that could inject its contents into the wall of the small intestine, because most of the drugs are absorbed in it. There are no pain receptors in this part of the body, which means that microinjections into the mucosa for drug delivery will be painless.
In order for the capsule to reach the small intestine and perform microinjections, the researchers coated it with a polymer that does not break down in the acidic environment of the stomach at a pH of 1.5 to 3.5. When the capsule reaches the small intestine, a higher pH level (about 6) causes it to rupture, and the three levers folded inside the capsule unbend.
Each lever contains soluble microneedles 1 millimeter long that can inject insulin or other medications. When the levers are unbent, the force of their release allows tiny microneedles to penetrate through the uppermost layer of the small intestine. After injection, the needles dissolve and release the drug.
The capsule is next to a 10-cent coin with a diameter of about 18 mm (bottom left). X-ray of the microcapsule in the intestine before and after the extension of the levers (top left). Levers are straightened, microneedles are visible (on the right). Source: MIT.
The researchers conducted several safety tests on animal and human tissues to make sure that when a drug delivery needle penetrates, there is no through perforation of all layers of the intestine or any other serious adverse events. The researchers designed the levers inside the capsule in such a way that they disintegrate into small parts after the release of the microneedles.
Demonstration of the operation of the capsule with insulin
In experiments on pigs, researchers have shown that capsules with a length of 30 millimeters can effectively deliver the necessary doses of insulin, this proved an immediate decrease in blood glucose levels. They also showed that the levers are safely removed from the body after the release of microneedles, without causing blockage in the intestinal lumen.
The researchers used insulin to demonstrate the new system, but they believe it could also be used to deliver other protein drugs, such as hormones, enzymes or antibodies, as well as RNA-based drugs.
Article by A. Abramson et al. A luminal unfolding microneedle injector for oral delivery of macromolecules is published in the journal Nature Medicine.
Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru based on the materials of MIT News: New capsule can orally deliver drugs that usually have to be injected.