Researchers at the University of British Columbia and the Paul Scherrer Institute in Switzerland have come up with a non-invasive way to monitor drugs in the bloodstream with a microneedle.

The researchers found that the fluid beneath the most outer-layer of skin can be used to detect the amount of drugs in the blood stream and can be reached by using a microneedle.

Microneedles are small and hollow with a needle-like projection that is less than half a millimetre long, designed to only penetrate the first layer of skin and not the epidermis or dermis like a standard hypodermic needle. This means the needle would not hit nerves, blood vessels or active immune cells.

“This is probably one of the smallest probe volumes ever recorded for a medically relevant analysis,” said Urs Hafeli, an associate professor in UBC’s faculty of pharmaceutical sciences.

Sahan Ranamukhaarachchi, a PhD student in UBC’s faculties of applied science and pharmaceutical sciences helped to create a particular microneedle to monitor the level of vancomycin, an anti-biotic used to treat serious infections, in patients. The drug is administered through an intravenous line and requires three to four blood draws per day to test the drug levels because it can cause life-threatening side-effects.

Together with his colleagues, Ranamukhaarachchi discovered that they could use the fluid under the outer layer of skin to test the blood for vancomycin levels, without having to invasively draw blood.

The microneedle collects less than a millionth of a millilitre of fluid. A reaction then occurs inside of the microneedle that is detected through an optical sensor to allow researchers to quickly and easily determine the drug levels.

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

The use of microneedles could replace costly and invasive blood draws as well as improve patient comfort.