Experimental technology created to maintain drug levels in body

A research team has developed a drug delivery tool that could make it easier for people to get the correct dose of lifesaving drugs.

As with coffee or alcohol, the way each person processes medication is unique. One person's perfect dose may be another person's deadly overdose. With such variability, it can be hard to prescribe exactly the right amount of critical drugs.

In a paper published this week in Nature Biomedical Engineering, the team led by Stanford University electrical engineer H. Tom Soh and postdoctoral fellow Peter Mage showed that the experimental drug delivery technology could continuously regulate the level of a chemotherapy drug in living animals.

It has three basic components: a real-time biosensor to continuously monitor drug levels in the bloodstream, a control system to calculate the right dose and a programmable pump that delivers just enough medicine to maintain a desired dose.

The sensor contains molecules called aptamers that are specially designed to bind a drug of interest.

When the drug is present in the bloodstream, the aptamer changes shape, which an electric sensor detects. The more drug, the more aptamers change shape.

That information, captured every few seconds, is routed through software that controls the pump to deliver additional drugs as needed. The researchers call this a closed-loop system, one that monitors and adjusts continuously.

The team tested the technology by administering the chemotherapy drug doxorubicin in animals.

Despite physiological and metabolic differences among individual animals, they were able to keep a constant dosage among all the animals in the study group, something not possible with current drug delivery methods.

The researchers also tested for acute drug-drug interactions, deliberately introducing a second drug that is known to cause wide swings in chemotherapy drug levels. Again, they found that their system could stabilize drug levels to moderate what might otherwise be a dangerous spike or dip.

"This is the first time anyone has been able to continuously control the drug levels in the body in real time," Soh said in a Stanford news release.

"This is a novel concept with big implications because we believe we can adapt our technology to control the levels of a wide range of drugs."

If the technology works as well in people as in their animal studies, it could have big implications.

"For example, what if we could detect and control the levels not only of glucose but also of insulin and glucagon that regulate glucose levels?" he said.

That could allow researchers to create an electronic system to replicate the function of the dysfunctional pancreas for patients with type 1 diabetes.

Many years of tests lie ahead to ensure that this technology is safe and effective for people, but the researchers believe it may be big step toward personalized medicine.

"Monitoring and controlling the actual dosage a patient is receiving is a practical way to take individual factors into account," said Soh.

And the technology could be especially helpful for pediatric cancer patients, who are notoriously difficult to dose because children's metabolism is usually different from adults. Endit