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Researchers have unveiled a new pill that could replace injections.

It can deliver drugs that cannot currently be delivered as a pill.

However, there is one caveat -  the pill is covered in tiny needles.

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The microneedle pill is coated with hollow needles. When the pill reaches the desired location in the digestive tract, the pH-sensitive coating surrounding the capsule dissolves, allowing the drug to be released.

Researchers at MIT and Massachusetts General Hospital (MGH) have devised a novel 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 team 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,' says Giovanni Traverso, who led the research, which appears 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 like arthritis and Crohn's disease. 

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,' says Carl Schoellhammer, a graduate student in chemical engineering and a lead author of the paper. 

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

When the pill has reached the desired location in the GI tract, the coating dissolves, revealing the microneedles. In the case of hollow microneedles (top right), the drug reservoir is compressed through peristalsis, releasing the drug through the needles. In the case of solid microneedles (bottom right), the drug is formulated into the microneedles. The microneedles lodge in the tissue where they can slowly dissolve and release their payload.

The MIT prototype acrylic capsule, 2 centimeters long and 1 centimeter in diameter, includes a reservoir for the drug and is coated with hollow, stainless steel needles about 5 millimeters 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.

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.