Determination of vancomycin content in dried blood spots for therapeutic drug monitoring

Blood spot collection is a simple method to obtain specimens for therapeutic monitoring of drugs, assessing drug adherence, and preventing any potential drug toxicity. A simple chromatographic method for the determination of vancomycin in dried blood spots (DBS) has been developed and validated. Intra and inter-day precisions (measured by CV%) were less than 11.5% and the accuracy deviation was less than 11%. The limits of detection (LOD) and quantification (LOQ) were 1 and 10 ng/mL, respectively. Interestingly, LOQ is smaller than the smallest vancomycin monitoring level. Stability analysis shows that vancomycin is stable for at least three weeks when stored at 4 to 8°C. The high sensitivity of detection and short time of analysis (less than 8 min), combining with the simplicity of the procedure made the method applicable for monitoring vancomycin in dried blood spots, which might be implemented in routine clinical settings.