Painless Inexpensive Microneedle System For Drug Monitoring

A new microneedle drug monitoring system that could one day replace costly, invasive blood draws and improve patient comfort has been developed by researchers at the University of British Columbia and the Paul Scherrer Institut (PSI) in Switzerland.

The system consists of a small, thin patch that is pressed against a patient’s arm during medical treatment and measures drugs in their bloodstream painlessly without drawing any blood. The tiny needle-like projection, less than half a milimetre long, resembles a hollow cone and doesn’t pierce the skin like a standard hypodermic needle.

Researcher Sahan Ranamukhaarachchi, a PhD student in UBC’s faculties of applied science and pharmaceutical sciences, who developed this technology during a research exchange at PSI, said:

“Many groups are researching microneedle technology for painless vaccines and drug delivery. Using them to painlessly monitor drugs is a newer idea.”

Microneedles are designed to puncture the outer layer of skin, which acts as a protective shield, but not the next layers of epidermis and the dermis, which house nerves, blood vessels and active immune cells.

Microneedle System For Drug Monitoring Vancomycin

The microneedle created by Ranamukhaarachchi and his colleagues was developed to monitor the antibiotic vancomycin, which is used to treat serious infections and is administered through an intravenous line. Patients taking the antibiotic undergo three to four blood draws per day and need to be closely monitored because vancomycin can cause life-threatening toxic side effects.

The researchers discovered that they could use the fluid found just below the outer layer of skin, instead of blood, to monitor levels of vancomycin in the bloodstream.

The microneedle collects just a tiny bit of this fluid, less than a millionth of a millilitre, and a reaction occurs on the inside of the microneedle that researchers can detect using an optical sensor. This technique allows researchers to quickly and easily determine the concentration of vancomycin.

“This is probably one of the smallest probe volumes ever recorded for a medically relevant analysis,”

said Urs Hafeli, associate professor in UBC’s faculty of pharmaceutical sciences.

“The combination of knowhow from UBC and PSI, bringing together microneedles, microfluidics, optics and biotechnology, allowed us to create such a device capable of both collecting the fluid and performing the analysis in one device,”

added Victor Cadarso, a research scientist and Ambizione Fellow at PSI.

Sahan A. Ranamukhaarachchi, Celestino Padeste, Matthias Dübner, Urs O. Häfeli, Boris Stoeber & Victor J. Cadarso
Integrated hollow microneedle-optofluidic biosensor for therapeutic drug monitoring in sub-nanoliter volumes
Scientific Reports 6, Article number: 29075 (2016) doi:10.1038/srep29075

Image: Sahan Ranamukhaarachchi