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New Drug-Delivery Capsule May Replace Injections

Pill coated with tiny needles delivers drugs directly into lining of digestive tract

Given a choice, most patients would prefer to take a drug orally instead of getting an injection. Unfortunately, many drugs, especially those made from large proteins, cannot be given as a pill because they are broken down in the stomach before they can be absorbed.

To help overcome that obstacle, researchers at the Massachusetts Institute of Technology (MIT) and Massachusetts General Hospital have devised a drug capsule coated with tiny needles that can inject drugs directly into the lining of the stomach after the capsule is swallowed. In animal studies, the researchers found that the capsule delivered insulin more efficiently than did 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 Dr. Giovanni Traverso, one of the lead authors of the paper, which appeared in the Journal of Pharmaceutical Sciences.

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, such as arthritis and Crohn’s disease. This class of drugs, known as biologics, also includes vaccines, recombinant DNA, and RNA.

Scientists have tried designing microparticles and nanoparticles that can deliver biologics, but such particles are expensive to produce and require a new version to be engineered for each drug.

Traverso and his 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 gastrointestinal (GI) tract. Their prototype acrylic capsule, 2 cm long and 1 cm in diameter, includes a reservoir for the drug and is coated with hollow, stainless steel needles about 5 mm 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. 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.

This approach could also be used to administer vaccines that normally have to be injected, the researchers say.

The team plans to modify the capsule so that peristalsis would slowly squeeze the drug out of the capsule as it travels through the GI tract. They are also working on capsules with needles made of biodegradable 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 concerns.

Source: MIT; October 1, 2014.

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