Toronto:Researchers have created an inexpensive microneedle drug monitoring system -- a thin patch pressed against a patient's arm -- that could one day replace costly, invasive blood draws and improve patient comfort. Microneedles are designed to puncture the outer layer of skin, which acts as a protective shield, but not the next layers of the epidermis and the dermis, which house nerves, blood vessels, and active immune cells. The new 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 millimetre long, resembles a hollow cone and does not pierce the skin like a standard hypodermic needle. "Many groups are researching microneedle technology for painless vaccines and drug delivery," said researcher Sahan Ranamukhaarachchi, Ph.D. student at the University of British Columbia in Canada. "Using them to painlessly monitor drugs is a newer idea," Ranamukhaarachchi, who developed this technology during a research exchange at Paul Scherrer Institut (PSI) in Switzerland, said. 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 allowed researchers to quickly and easily determine the concentration of vancomycin. The microneedle monitoring system was described in a paper published in the journal Scientific Reports.