Thursday, March 20, 2008

The Networked Pill

A new information system records what pills do to the body.

By Michael Chorost

Smart pill: Proteus's system consists of a pill that contains an "ingestible event marker" powered by a thin-film battery. Its electrical signal is picked up by sensors on a patch worn either on or just under the skin. The data are sent to a caregiver who looks for correlations between use of the medication and the patient's condition. Credit: Proteus Biomedical

A system that monitors pill taking and its effects is being engineered by a Silicon Valley startup. The technology consists of pills that report when they've been taken, and sensors that monitor the body's responses.

The company behind the technology, Proteus Biomedical, of Redwood City, CA, calls its technology the Raisin system. George Savage, Proteus's cofounder and a former ER physician, says that the company was motivated by the fact that so many medical problems stem from drug compliance problems. According to Savage, 40 percent of hospital readmissions for heart failure happen because patients fail to take their medications properly.

Even when a regimen is followed, it may not be the best regimen. According to Leslie Saxon, a cardiologist at the University of Southern California, who works as a consultant for Proteus, the dosages of drugs used for heart failure are derived from large clinical trials and may not meet a particular patient's needs. "Imagine a situation where drug ingestion is tracked, and heart pressure before, immediately after, and later are known," says Saxon. "That represents real, individualized, tailored drug therapy."

In the Raisin system, each pill contains an "ingestible event marker" (IEM). The IEM consists of a sand-grain-size microchip with a thin-film battery that is activated on ingestion, as it is exposed to water. The battery, Proteus says, is nontoxic because it is made from materials similar to those in a vitamin pill. Once swallowed, the IEM sends through the body's tissues a high-frequency electrical current that's modulated in such a way that it provides a unique marker of the pill. It's not an RFID technology: it uses the conductive tissues of the body to conduct the signal, rather than a radio, and the signal is confined within the body. Mark Zdeblick, the company's CTO, says that the IEMs could cost less than a penny each when manufactured in volume.

The electrical current is picked up and logged by a receiver on a patch placed on the patient's chest or abdomen, or placed underneath the skin as a subcutaneous insert. The receiver also contains sensors that monitor physiological parameters such as heart rate, respiration, and bodily movement. Heart rate is monitored by detecting the electrical activity of the heart; respiration is monitored by detecting changes in the impedance of the electrodes as the chest expands and contracts; activity is monitored with a miniature accelerometer, similar to the ones in iPhones. Combining the parameters can reveal behavioral measures such as sleep patterns.

Monitoring chemistry-based parameters such as blood glucose with subcutaneously implanted chips is possible in principle, says Ben Costello, Proteus's vice president of sensor development, although it's more challenging to do technologically. For the present, the company is focusing on biophysical parameters that can be measured on top of the skin.

Once collected, the data are uploaded to a server via a cell phone or a PC for a caregiver's scrutiny. The patient can then be advised to adjust dosages or change medications.