Controlling a pill as it moves through a patient’s body could let doctors deliver drugs to precisely the right location—for instance, a tumor in the colon.
Researchers at Brown University have demonstrated a way to safely control a maneuverable pill and watch as it passes through the gastrointestinal tract.
Aside from looking for traces in a patient’s bloodstream, it is hard for doctors to tell if a drug has been delivered properly. “You can take X-rays [of tagged pills], but you can never really know what time the drug was released,” says Edith Mathiowitz, an associate professor of medical science and engineering at Brown University and principal investigator on the project. Mathiowitz’s team, which focuses on creating better drug-delivery technologies, originally built a magnetic tracking system to observe pills as they pass through the body. But the researchers soon realized they could control the pills as well.
“What we developed could be extremely useful for improving bioavailability for drugs that have even narrow therapeutic windows,” says Mathiowitz, referring to drugs that are absorbed only in specific regions of the gastrointestinal tract. “You can use it in two ways: a retention system for the stomach [to ensure the patient receives the desired dosage] and for localization in specific regions of the gastrointestinal tract—regions that are very hard to reach.”
In experiments, Mathiowitz’s team moved pills through the stomachs and intestines of rats. They developed a system to measure and control the force between a one-millimeter-long magnet within the pill and a large external magnet used to control its movement. The system automatically moves the external magnet closer to or farther from the pill’s magnet to maintain the minimum amount of force that will manipulate the pill, avoiding harm to the animal’s intestine or stomach.
Other researcher groups have shown that capsules can be manipulated inside the body magnetically, but they have not focused on minimizing the force used, explains Bryan Laulicht, first author of the research paper describing the work, published today in the online edition of the journal Proceedings of the National Academy of Sciences. “The prevailing thought was to use as much force as possible,” he says. “Our real push was to emphasize the safety.”