Progress of capillary electrophoresis in therapeutic drug monitoring and clinical and forensic toxicology

During the past decade, capillary electrophoresis (CE) emerged as a promising, effective, and economical approach for the analysis of licit and illicit drugs and their metabolites in biologic samples. This review provides an overview of the principles of CE, the features of CE instrumentation, and the key aspects of CE-based drug assays that were developed for therapeutic drug monitoring (TDM), clinical and forensic toxicology, and assessment of drug metabolism and pharmacokinetics. CE performed in fused-silica capillaries has sufficiently matured and can thus be applied routinely, whereas chip-based instrumentation comprising fully integrated assays is still in development. Despite the attractive advantages of electrokinetic capillary technology, relatively few CE-based assays for TDM and for drug screening of clinical and forensic interest have been adopted in the routine arena. The lack of complete systems designed for unattended operation, the reluctance of bioanalysts to replace a satisfactory existing method, and tight budgets are believed to have hindered the widespread replacement of older (mainly chromatographic) technology. Another limitation of CE is that this technique is somewhat less sensitive than other analytic techniques used for drug analysis in biologic fluids. New instrumental developments featuring user-friendly software and the introduction of assay kits, however, should increase the number of validated CE drug tests becoming used on a routine basis.