US scientists have made an easy-to-swallow device to controllably deliver cancer drugs into the body. After treatment, the device passes safely out of the body through digestive tract, they claim.

Fluorescence imaging can be used to view drugs in the microdevice

Many cancer drugs must be injected into the bloodstream because they cannot pass easily into the blood through the walls of the stomach and intestine. To overcome this barrier to oral delivery, Tejal Desai and colleagues at the University of California, San Francisco, made a polymer-based microdevice with a tiny reservoir in the centre. They filled the reservoir with a polymer-derived gel known as a hydrogel, which can store drugs and release them in a controlled way.

Desai loaded the hydrogel with a drug and tested the device on a model that mimics cell absorption. She found that the device seemed to concentrate release of the drug at the cell interface, increasing permeability through the cells. In addition, because the device released the drug slowly over a period of time, it limited the amount of free drug, preventing damage to surrounding tissues.

'The devices can be used to deliver a variety of cancer drugs,' says Kristy Ainslie, who works on the project. 'This creates a broad range of treatment options for cancer patients so they are treated better, more effectively and with fewer side effects.'

'This is an innovative application of microfabrication technology, which is already used to cost-effectively mass-produce sophisticated computer chips and miniature air-bag deployment sensors,' enthuses Shuvo Roy, a biomedical engineer from the Cleveland Clinic Lerner Research Institute, US.

Desai's group plan additional studies with the microdevice, using models that more closely mimic the digestive tract. They are considering the possibility of using hydrogels with triggered release options, to turn the release of drugs on and off on demand.

Rachel Cooper