A pill coated with tiny needles that can deliver drugs directly into the lining of the digestive tract has been developed by scientists, an advance that may eliminate the need for injections. In animal studies, researchers at Massachusetts Institute of Technology (MIT) and Massachusetts General Hospital (MGH) found that the capsule delivered insulin more efficiently than injection under the skin, and there were no harmful side effects as the capsule passed through the digestive system.
"This could be a way that the patient can circumvent the need to have an infusion or subcutaneous administration of a drug," said Giovanni Traverso, a research fellow at MIT's Koch Institute for Integrative Cancer Research, and one of the lead authors of the study.
Although the researchers tested their capsule with insulin, they anticipate that it would be most useful for delivering biopharmaceuticals such as antibodies, which are used to treat cancer and autoimmune disorders like arthritis.
This class of drugs, known as "biologics," also includes vaccines, recombinant DNA, and RNA. "The large size of these biologic drugs makes them nonabsorbable.
And before they even would be absorbed, they're degraded in your GI tract by acids and enzymes that just eat up the molecules and make them inactive," said Carl Schoellhammer, a graduate student in chemical engineering and a lead author of the paper. Schoellhammer, Traverso, and their colleagues set out to design a capsule that would serve as a platform for the delivery of a wide range of therapeutics, prevent degradation of the drugs, and inject the payload directly into the lining of the GI tract.
Their prototype acrylic capsule, 2 centimetres long and 1 centimetre in diameter, includes a reservoir for the drug and is coated with hollow, stainless steel needles about 5 millimetres long. 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.
Since 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.
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 insulin was given by subcutaneous injection. The study appears in the Journal of Pharmaceutical Sciences.