Sensors Monitor Drug Usage
ATLANTA, March 10, 2008 -- A sensor necklace that records the exact time and date when pills are swallowed and reminds the user if doses are missed could help the one in three adults in the US who fail to take their medicines as prescribed, or anyone else who occasionally forgets.
"Forgetfulness is a huge problem, especially among the elderly, but so is taking the medication at the wrong time, stopping too early or taking the wrong dose," said Maysam Ghovanloo, assistant professor in the Georgia Institute of Technology's School of Electrical and Computer Engineering. "Studies show that drug noncompliance costs the country billions of dollars each year as a result of rehospitalization, complications, disease progression and even death."
According to a 2005 Wall Street Journal/Harris Poll, one in three US adults who had been prescribed drugs to take on a regular basis reported that they did not follow the doctor-recommended course of treatment, with two-thirds reporting that they simply forgot to take their medication.
Assistant professor Maysam Ghovanloo (top) and graduate student Xueliang Huo, both of Georgia Institute of Technology's School of Electrical and Computer Engineering, test their drug compliance monitoring system on an artificial neck. As a magnetic pill passes through the esophagus, the date and time are sent wirelessly to a computer and recorded. (Photos by Gary Meek)
To address this problem, Ghovanloo and graduate student Xueliang Huo designed a sensor necklace that records the date and time a specially designed pill is swallowed, which they hope will increase drug compliance and decrease unnecessary health care costs. The device could also be used to ensure that subjects in clinical drug trials take medications as directed by the research team.
The necklace, called MagneTrace, contains an array of magnetic sensors that could be used to detect when a specially-designed medication containing a tiny magnet passes through a person’s esophagus. The device can also be incorporated into a patch attached to the chest.
The date and time the user swallowed the pill can be recorded on a handheld wireless device, such as a smartphone, carried on the user’s body. The information can then be sent to the patient’s doctor, caregiver or family member over the Internet. The device can notify both the patient and the patient’s doctor if the prescribed dosage is not taken at the proper time.
This technology can also help researchers and pharmaceutical companies conduct more accurate clinical trials of new drugs. Currently, compliance is determined by medication diaries kept by the patients, but patients are prone to fill out diaries just before meetings held to monitor their progress and they may adjust their medication to compensate for missed doses.
Inaccurate data from clinical trials can affect decisions made about new drugs, potentially impacting millions of people.
“If each drug trial volunteer had to wear a MagneTrace necklace, the exact date, time and dose would be recorded, rather than relying on the patient’s memory and honesty,” Ghovanloo said.
This technology also has the potential to reduce the size of clinical trials and reduce the need to repeat them. This alone can reduce drug company expenditures, in turn reducing the cost of new drugs for consumers. MagneTrace is suitable for small- and large-scale clinical trials, as well as individual patients, according to Ghovanloo.
“A patient cannot cheat the system by passing the pill past the necklace sensors on the outside of the neck because the signal processing algorithm is smart enough to only look for the pill’s magnetic signature while it passes through the esophagus,” said Ghovanloo, who started working on this project about two years ago at North Carolina State University.
The researchers designed and tested an artificial neck, built from a PVC pipe filled with plastic straws. They place a necklace containing an array of sensitive magneto-inductive sensors around the artificial neck to study detection of a pill passing through it.
MagneTrace is a sensor necklace that sends the date and time a pill is swallowed to a wireless device. Assistant professor Maysam Ghovanloo hopes the device will increase drug compliance with the elderly and clinical drug trial participants.
The magnetic sensors are distributed in different orientations, allowing the pill to be detected regardless of its orientation when it passes through the esophagus. The sensors are driven by a control unit on the necklace that consists of a battery, power management circuitry, low-power microcontroller and radio frequency wireless transceiver. The prototype necklace with six sensors weighs less than one ounce.
“Preliminary results testing the artificial neck have shown 94.4 percent correct detections when the magnetic tracer passed through the esophagus detection zone and about six percent false positives when it passed through areas not in the detection zone,” said Ghovanloo.
Another benefit to MagneTrace is that it monitors ingestion, he said, unlike monitors currently on the market.
“Other devices just tell the doctor if a pill bottle was opened. These devices are not smart enough to tell how many pills, if any, were removed from the bottle, nor if the pill was actually ingested by the intended patient,” said Ghovanloo.
One device that actually monitors ingestion uses an optical sensor to detect a fluorescent dye incorporated in the medication as it enters the bloodstream.
“The problem with this technology is that a patient must add an additional chemical to his/her body and the potential long-term negative side effects of the fluorophores on the human body have not yet been well studied,” he said.
MagneTrace, on the other hand, was designed so that it would have no effect on the body, he said. Multiple strong magnets in the gastrointestinal tract can potentially result in a blockage. However, the magnet used in the pill or capsule is very small -- 3-mm in diameter and about 1-mm thick -- and coated with a thick, indigestible, insoluble polymer coating that prevents absorption of the magnet and prevents magnets from aggregating.
While the device has not yet been tested on animals or humans, theoretical and experimental analyses show that the coating can reduce the force of the magnets to less than that created by the weight of the tracers.
“The magnet should simply pass through a patient’s gastrointestinal tract with no interactions and be excreted from the body in about 24 hours without any effects,” said Ghovanloo.
The details of the proof-of-concept device were published in the December 2007 issue of IEEE Sensors Journal.
For more information, visit: www.gatech.edu
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