Pills equipped with tiny needles can inject a body from the inside

For those of us who cringe at the sight of needles, there may someday be a less daunting alternative to getting a shot: swallowing a pill-sized device that delivers medication by painlessly pricking the inside of the stomach.

A prototype of the device, described in the Feb. 8 Science, administers insulin. But similar ingestible capsules could also replace skin injections of antibodies for cancer treatment, hormones and other pharmaceuticals.

Each ingestible device is about the size of a pea and shaped like an acorn, with a lightweight polyester “nut” and stainless steel cap. The shape is designed to guide the device to rest, cap down, on the floor of the stomach. There, it sticks a needle tip composed almost entirely of insulin a few millimeters into the mucus membrane lining the stomach. Once the insulin needle tip dissolves, the device passes through the rest of the digestive system.

Thanks to the dearth of sharp pain receptors inside the stomach, the tiny injection “is unlikely to cause any discomfort,” says study coauthor Giovanni Traverso, a gastroenterologist and biomedical engineer at Brigham and Women’s Hospital in Boston and MIT.

In experiments with pigs, the swallowable devices delivered a similar amount of insulin to the bloodstream as skin injections. One week after treatment, the researchers found no signs of tissue damage in the animals’ stomachs.

“The design of their device is clever,” says Jean-Christophe Leroux, a drug formulation and delivery researcher at ETH Zurich not involved in the work. But he wonders if there could be long-term consequences of repeated internal pinpricks in patients, such as people with diabetes, who must inject themselves with medication throughout their lifetimes. The study’s researchers say future work will help determine if there are any chronic effects.