Boston | Scientists have designed a new type of pill that, once swallowed, can attach to the lining of the gastrointestinal tract and slowly release its contents. The tablet is engineered so that one side adheres to tissue, while the other repels food and liquids that would otherwise pull it away from the attachment site.
Such extended-release pills could be used to reduce the dosage frequency of some drugs, researchers said. For example, antibiotics that normally have to be taken two or three times a day could be given just once. This could be adapted to many drugs.
Any drug that is dosed frequently could be amenable to this kind of system, said Giovanni Traverso, a research affiliate at Massachusetts Institute of Technology (MIT) and a gastroenterologist at Brigham and Women’s Hospital. To achieve long-term drug release in the gastrointestinal (GI) tract, the researchers focused on a type of material known as mucoadhesives, which can stick to the mucosal linings of organs such as the stomach.
Scientists have previously explored using this kind of material for drug delivery to the GI tract, but it has proven difficult because food and liquid in the stomach become stuck to the tablet, pulling it away from the tissue before it can deliver its entire drug payload. To overcome this challenge, the researchers created a dual-sided device, called a Janus device.
One side sticks to mucosal surfaces, while the other is omniphobic, meaning that it repels everything it encounters. For the mucoadhesive side, the researchers used a commercially available polymer known as Carbopol. The omniphobic side consists of cellulose acetate that the researchers textured so that its surface would mimic that of a lotus leaf. They then fluorinated and lubricated the surface, making it repel nearly any material.
The researchers used a pill presser to combine the polymers into two-sided tablets, which can be formed in many shape and sizes. Drugs can be either embedded within the cellulose acetate layer or placed between the two layers. Using intestinal tissue from pigs, the researchers tested three versions of the tablet – a dual-sided mucoadhesive tablet, a dual-sided omniphobic tablet, and the Janus version, with one mucoadhesive side and one omniphobic side.
To simulate the tumultuous environment of the GI tract, the researchers flowed a mix of food including liquids and small pieces of bread and rice along the tissue and then added the tablets. The dual-sided omniphobic tablet took less than 1 second to travel along the tissue, and the dual-sided mucoadhesive stuck to the tissue for only 7 seconds before being pulled off. The Janus version stayed attached for the length of the experiment, about 10 minutes.
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