Biosensor-Based Drug Monitoring

Abstract

Biosensor-based drug monitoring -- the real-time, minimally invasive measurement of drug concentrations in biological matrices 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 assays require phlebotomy, sample transport, and analytical turnaround times of 2-48 hours that prevent real-time dose adjustment during rapid pharmacokinetic changes. Wearable and implantable biosensors capable of continuous or near-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 loop enabling 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, chemotherapy agents, and cardiac drugs; 2018-2024) comparing detection sensitivity, selectivity, and correlation with conventional laboratory TDM across biosensor platforms. A Biosensor Drug Monitoring Quality Index (BDMQI) integrating analytical performance, clinical matrix compatibility, miniaturisation potential, and regulatory pathway clarity predicted conventional TDM 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.