Implantable biosensor monitors real-time metabolism of drugs

Researchers and collaborators of the Soh lab at UC Santa Barbara have developed an implantable device to monitor real time concentrations of medications in the blood. The device, called the MEDIC (Microfluid Electrochemical Detector for In Vivo Concentrations), aims to address an increasingly identified problem in medicine – that people metabolize and respond to the same medication at the same dose in very different ways.

A great deal of focus has been on identifying genetic polymorphisms and other markers that can be used to identify patients who are either resistant to certain medications or at risk for adverse effects – think HLA typing prior to initiating Tegretol therapy.

This device aims to open new opportunities into the personalization of medicine.

According to Kevin Plaxo, professor of chemistry, biomolecular science and an engineer, “Current dosing regimens are really quite primitive.” Today, a drug’s dosing is determined by a patient’s age and weight. Maintenance doses are subsequently calculated based on these metrics along with standardized rates of metabolism. The MEDIC device would allow this process to become personalized.

The device itself consists of a chamber through which a constant stream of the patient’s blood runs. At the base of the chamber, small sensing molecules called aptamers bind the drug molecules. Once the drug molecule is bound to the aptamer, a tiny jolt of current is sent to an external device so the drug concentration can be calculated.

Here is a video of the researchers describing the MEDIC device.

The researchers have overcome the problem of particles in natural blood sticking to and coating the sensor by adding a buffer layer to the chamber.

Scott Ferguson, a lead author on this study, explains,

“Think of swimmers swimming from one bank of a river to another across a fast-moving current. The faster swimmers can make it across the stream, while the slower swimmers get carried downstream by the current. In this way, the slower, larger blood components continue to move along the blood flow stream while the smaller, faster-moving molecules can cross from the blood flow through the buffer to the sensors.”

Current trials of the device have been reported to be successful. The aptamers have been able to detect the presence of minute concentrations of the drug, even with similar competing molecules in the blood.

In addition to its impact on healthcare administration, this device could change the current approval process for pharmaceuticals. If the real-time drug metabolisis and effect can be measured, drug dosing can be adjusted to an individual, therefore increasing that drug’s window of efficacy.

The researchers of the Soh lab imagine more, far-reaching possibilities for the MEDIC device. In the future, they envision attaching the device to the body’s natural feedback loops so that it can administer drugs automatically. For now, though, the MEDIC is in early stages of clinical trials. It may be many years until it is regularly used in medical settings.

Source: University of California, Santa Barbara

Author:

Pooja Jaeel

Pooja is currently a first year medical student at Keck School of Medicine at USC. She graduated from UC Berkeley in 2012 with a degree in Molecular and Cell Biology and a minor in Rhetoric. She is interested in how technology can be applied to underserved communities to enhance medical care, treatment compliance, and foster a stronger patient/physician relationship.

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