Breath Analyzer Monitors Drug Compliance

A new device could lead to better clinical trials.

For those with HIV, missing doses of medication can have a serious effect: it can make the deadly virus more drug resistant. Doctors have been trying to devise ways to monitor drug compliance among patients with a wide range of diseases. But each method has limitations. Patients who self-report aren't always honest, and counting pills left in the bottle only indicates how many have been removed, not necessarily how many have been taken.

Breath check: Xhale’s Self-Monitoring and Reporting Therapeutics (SMART) device, illustrated above, analyzes a person’s breath to detect if medication has been ingested. The device, which is about the size of a shoebox, could help doctors track drug compliance. Credit: Robrady

Researchers at the University of Florida and Xhale are taking a different approach: they're utilizing an off-the-shelf breath analyzer to confirm if a patient has taken her pills. The technique is straightforward. After a patient takes a pill, she breathes into a strawlike tube on the analyzer, which detects a compound in the medication. Instead of looking for the presence of complex and varying drugs, the researchers put an FDA-approved compound--an alcohol called 2-butanol--in the pills that they used during testing. Enzymes in the stomach convert the alcohol into a gas, which is what the device detects. The premise is that if the system proves useful, a wide range of drugs could be reformulated to include the alcohol.

The analyzer was originally developed for the military to test the surrounding air for agents of chemical warfare, says Richard Melker, a University of Florida professor and chief technology officer at Xhale. The team modified the device to add the straw and detect the alcohol. The screen on the front of the box provides instructions on which buttons to press and when to breathe into the straw. It also records the presence or absence of the telltale gas, as well as the time. The user can then upload this information from the device on a USB port and take it to a health-care provider.

Currently, the device is targeted toward pharmaceutical companies, which have no way to tell for sure if participants in clinical trials are taking the medicine as required. Ensuring drug compliance may make clinical trials more effective, says Melker, particularly because participants paid to take the medicine may not be honest if they skip doses. "We believe that having quality data will dramatically decrease the cost of trials, and that the drugs approved by the FDA would be safer," says Melker.

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A successful means of measuring drug compliance is needed, agrees Martin Hirsch, a professor of medicine at Harvard Medical School. "The number-one reason for failure of therapy in HIV infection is poor adherence," he says.

Mallory Johnson, an associate professor of medicine at the University of California, San Francisco, who works on patient adherence at the Center for AIDS Prevention Studies, says that most doctors use self-reporting to monitor adherence, in addition to using compartmentalized pill organizers and pharmaceutical records. Researchers sometimes use pill bottles with sensors on the lid that indicate each time the bottle is opened. But this method doesn't always work, says Johnson, because often patients don't carry around the whole bottle. Attempts to remind people to take pills, such as text messages or phone calls, haven't been shown to be extremely effective either. "Behavioral reminders are important, but not enough," says Johnson. He adds that people tend to overestimate how much they comply with taking medicine. "I think we absolutely need innovative approaches for measuring adherence," says Johnson, who was not involved in the Xhale project. "I imagine this [device] being particularly useful in controlled clinical trials, where it's critical to know whether someone took doses of medicine." But for individuals who have difficulty following medical regimens, he's not sure it will help. He points out that "you still rely on someone being adherent on using this device."