The US FDA recently approved Proteus Digital Health Ingestion Event Marker (IEM). Basically, it’s a pill with some electronics attached (very tiny electronics: around 0.5mm in diameter for a total weigth of 5mg, see picture below). Once activated the pill transmit a signal and, coupled with a detector, you know when the pill got into your body.

When you think of it, it seems very interesting. The direct potential application (Proteus is only making the IEM, not the pill itself on which the IEM is attached) is to monitor when a patient actually take her/his pills. Or for the patient, just to remember if the pill was taken already or not (you can also use boxes with specific places for each day). Some people see here a plot against human health in general – maybe. But as I use to say: watch the use, don’t punish the tools. The IEM could of course be used to ensure patient’s compliance and increase the surveillance. But on the other end, the IEM could also help decide if a properly taken medication (from “Big Pharma” or from “natural products”) is indeed efficacious.

Another direct application is the correct identification of pills before consumption. There are a lot of websites that will help us correctly identify pills found outside boxes at home (see here for instance). If you activate the IEM on a pill, the signal emitted can directly tell you which medication it is. Provided the signal emitted contains an unique signature.

And there I have some questions … Kit Yee Au-Yeung and her colleagues published an abstract (PDF) at Wireless Health 2010 about the technology. The detailed paper explains well some aspects of the IEM like the way the battery actually uses the patient’s body fluids to power a redox reaction (very simple – hence clever to use it here). But the paper doesn’t say the distance at which the signal can be recorded nor how this signal is encoded.

How far can you measure the signal from this IEM? The paper states that the “communication process remains entirely within the body; it is unnoticed by and not detectable beyond the patient consumer“. It goes into several measures during the reported clinical studies but does not mention how far the signal can be measured. In my opinion, the IEM signal cannot be detected from very far for various reasons: the statement copied above, the output of this type of redox reaction and size of substrate used and the way they define their scheduling adherence. In this definition, a “sensor-enabled medication was considered taken “on-time” when ingested within ± 1 hour and ± 2 hours of the specified time“. Since the IEM is activated as soon as in contact with body fluids and the sensor/detector is placed approximately next to the stomach, I guess the sensor only detects the IEM signal when the IEM actually reaches the stomach. I wonder if one would place the sensor just below the throat, will the time-to-detection be shortened?

How is the signal encoded? The paper reports an identification accuracy of 100%, meaning all detected sensors were correctly identified. It also reports a sensitivity of 97.7%, meaning the study did not detect the negative controls in 97.7% of cases of ingested negative controls. Good. Now what happens if you ingest several different medications at the same time? They will most probably reach the stomach at the same time too and their respective signals will be detected at the same time. The paper says that the sensor/detector “interprets the information from the edible sensor, identifies it as unique“. How? We don’t know. From previous experiment I know it is feasible to encode a somehow unique signal in 5mm of electronics. Up to how many different signals can be encoded (and decoded, given a weak signal)? This will give the maximum number of e-pills you can ingest at the same time.

Although the FDA only approved it for placebo pills so far, it is a very interesting first step towards the control/cure of chronic diseases, sometimes requiring to follow a long-term medication plan. Although the pill is kind of passive and the whole system (*) only measures when a pill is actually ingested, more active e-pills will come to market, for instance only releasing one of their drugs when receiving a signal or delivering a dose adapted to the environment in which they are. Later on you can imagine e-pills acting like Proteus (sic!) in the Fantastic Voyage …

A video for the end? There is an official video on Vimeo but I like this one:

(*) the whole system involves a wearable sensor/detector/patch as well as a “social” application on smartphone. The sensor was already approved by the FDA a long time ago (under the name of “Raisin Personal Monitor”). From the official screenshot the app also reports activity (including sleep), heart beat, blood pressure, etc. (as many other apps around now). Could be cool to try this!

Photo credits: antenna picture by Giacomo Boschi on Flickr (CC-by) and oscilloscope signal by Mikael Alternark on Flickr (CC-by).