Minimally invasive microneedle-based systems show promise as tools for real-time monitoring of kidney health. Now, Sam Emaminejad and colleagues report on a new microneedle biosensor capable of providing real-time assessment of liver and kidney drug clearance in a rat model.

“We paired our nanocavity-textured microneedle electrode with a bioanalytical framework that translates interstitial fluid measurements into blood-equivalent pharmacokinetic parameters,” explains Emaminejad. The potential of this RNB for therapeutic drug monitoring in vivo was confirmed by the concordance between the RNB data and blood levels of the liver-metabolized chemotherapy drug irinotecan in healthy rats; the biosensor data also showed prolonged drug half-life in rats with liver damage. As for kidney drug clearance, the RNB data from vancomycin-treated healthy rats correlated strongly with the dose-dependent changes in drug levels measured in blood. In rats with adenine-induced kidney injury, the biosensor data not only showed lower drug clearance concordant with a reduction in glomerular filtration rate but, when animals were allowed to recover for 2 weeks from the high-adenine diet, it also reflected improvements in kidney function. Of note, early in the disease induction phase, RNB-detectable decreases in drug clearance preceded the increase in blood creatinine levels.