Smart Capsule Delivers Payload to Large Intestines

An innovative drug delivery capsule could deliver drugs directly to the gastrointestinal (GI) tract to target certain medical conditions.

Developed by researchers at Purdue University (West Lafayette, IN, USA), the 9×26 mm capsule is comprised of two compartments; one contains a charged capacitor and a reed switch, while the second one houses the drug reservoir, capped by a taut nylon thread intertwined with a nichrome wire connected to the capacitor through the reed switch. The capsule meanders through the intestines until it reaches the target location within the GI tract, which is marked by an implanted miniature magnetic marker or an externally-worn larger magnet.

The proximity to the magnet activates the reed switch, which discharges the capacitor into the nichrome wire, melting the nylon thread. This releases a spring-loaded mechanism that opens the capped capsule to deliver the medication. A prototype capsule, about the same size as a standard gelatin capsule, was designed to release its powdered payload just before reaching the ileocecal valve, the meeting point of small and large intestines. A study describing the capsule was published in the September 2015 issue of IEEE Transactions on Biomedical Engineering.

“Usually, when you take medication it is absorbed in the stomach and small intestine before making it to the large intestine; however, there are many medications that you would like to deliver specifically to the large intestine, and a smart capsule is an ideal targeted-delivery vehicle for this,” said senior author, Professor of electrical and computer engineering Babak Ziaie, PhD. “People are sometimes treated for C. difficile by transplanting feces from another person into the patient's large intestine, which provides vital microbes. However, it might be possible to convert the microbes into a powder through freeze-drying and deliver them with smart capsules instead.”

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