Just about everyone hates needles and many, especially kids, refuse them altogether due to overwhelming fear. Nevertheless, certain drug types including proteins get broken down by the digestive system and can only be administered through the skin. A new idea to combine a mechanical pill with microneedles on its surface may allow many existing drugs to now be taken orally.
Don’t worry, the pill comes coated with a pH sensitive material that dissolves once it reaches the intestines. This allows it to look like a traditional pill while not irritating the esophagus during ingestion. Once inside the intestine and the coating is off, the muscles of the intestine that propel food forward squeeze on the pill, forcing the contents to push through the microneedles. The pill continues on its way and is secreted the usual way, hopefully without too much discomfort.
The researchers tested the system on pigs and demonstrated that insulin delivered through the new pill had a significantly more impressive bioavailability than using traditional injections. Moreover, they showed that the pigs safely passed the pills and that they were “well tolerated” by the animals.
This technology is still at a proof of concept stage, but many, including millions of diabetics the world over, have new hope that life will be a little better without needles and syringes.
Previous studies of accidental ingestion of sharp objects in human patients have suggested that it could be safe to swallow a capsule coated with short needles. Because there are no pain receptors in the GI tract, patients would not feel any pain from the drug injection.
To test whether this type of capsule could allow safe and effective drug delivery, the researchers tested it in pigs, with insulin as the drug payload. It took more than a week for the capsules to move through the entire digestive tract, and the researchers found no traces of tissue damage, supporting the potential safety of this novel approach.
They also found that the microneedles successfully injected insulin into the lining of the stomach, small intestine, and colon, causing the animals’ blood glucose levels to drop. This reduction in blood glucose was faster and larger than the drop seen when the same amount of glucose was given by subcutaneous injection.
“The kinetics are much better, and much faster-onset, than those seen with traditional under-the-skin administration,” [Giovanni Traverso, a research fellow at MIT’s Koch Institute for Integrative Cancer Research, a gastroenterologist at MGH] says. “For molecules that are particularly difficult to absorb, this would be a way of actually administering them at much higher efficiency.”
This approach could also be used to administer vaccines that normally have to be injected, the researchers say.
The team now plans to modify the capsule so that peristalsis, or contractions of the digestive tract, would slowly squeeze the drug out of the capsule as it travels through the tract. They are also working on capsules with needles made of degradable polymers and sugar that would break off and become embedded in the gut lining, where they would slowly disintegrate and release the drug. This would further minimize any safety concern.
Study in Journal of Pharmaceutical Sciences: Microneedles for Drug Delivery via the Gastrointestinal Tract…
Press release: New drug-delivery capsule may replace injections…