Can a smartwatch track medication levels help personalize treatments? Researchers from UCLA Samueli School of Engineering and Stanford School of Medicine have demonstrated this in a new study published in the Proceedings of the National Academy of Sciences.

The researchers found that drug levels inside the body can be tracked in real-time using a custom smartwatch that analyzes the chemicals found in sweat.

According to the researchers, current efforts to personalize the drug dosage rely heavily on repeated blood draws at the hospital. The samples are then sent out to be analyzed in central labs. These solutions are inconvenient, time-consuming, invasive, and expensive. That is why they are only performed on a small subset of patients and on rare occasions.

"We wanted to create a wearable technology that can track the profile of medication inside the body continuously and non-invasively," study leader Sam Emaminejad, an assistant professor of electrical and computer engineering at UCLA, said in a release. "This way, we can tailor the optimal dosage and timing of the intake for each individual. And using this personalization approach, we can improve the efficacy of the therapeutic treatments."

Because of their small molecular sizes, many different kinds of drugs end up in sweat, where their concentrations closely reflect the drugs' circulating levels. That's why the researchers created a smartwatch, equipped with a sensor that analyzes the sampled tiny droplets of sweat.

The team's experiment tracked the effect of acetaminophen, a common over-the-counter pain medication, on individuals over the period of a few hours. First, the researchers stimulated sweat glands on the wrist by applying a small electric current, the same technique that Emaminejad's research group demonstrated in previous wearable technologies.

This allowed the researchers to detect changes in body chemistry, without needing subjects to work up a sweat by exercising. As different drugs each have their own unique electrochemical signature, the sensor can be designed to look for the level of a particular medication at any given time.