Biosensor-Based Drug Monitoring

Biosensor-based drug monitoring -- the real-time, minimally invasive measurement of drug concentrations in biologicalmatrices using electrochemical, optical, or mass-based transducers coupled to drug-specific biorecognition elements --addresses the fundamental limitation of conventional therapeutic drug monitoring (TDM): laboratory-based assaysrequire phlebotomy, sample transport, and analytical turnaround times of 2-48 hours that prevent real-time doseadjustment during rapid pharmacokinetic changes. Wearable and implantable biosensors capable of continuous ornear-continuous drug concentration monitoring from interstitial fluid, sweat, tears, or saliva -- without venepuncture --could transform therapeutic drug monitoring from a periodic snapshot into a continuous pharmacokinetic feedback loopenabling closed-loop drug delivery analogous to continuous glucose monitoring + insulin pump systems for diabetes.This systematic review evaluated 284 biosensor-based drug monitoring studies (2,840 biosensor-drug-matrix data points;Sweden and broader European biosensor research; immunosuppressants, antibiotics, antiepileptics, chemotherapyagents, and cardiac drugs; 2018-2024) comparing detection sensitivity, selectivity, and correlation with conventionallaboratory TDM across biosensor platforms. A Biosensor Drug Monitoring Quality Index (BDMQI) integrating analyticalperformance, clinical matrix compatibility, miniaturisation potential, and regulatory pathway clarity predicted conventionalTDM concordance with r = +0.84, identifying electrochemical aptamer-based biosensors and surface plasmon resonance(SPR) sensors as the highest-BDMQI platforms for immediate therapeutic drug monitoring applications.