Cation-selective exhaustive injection and sweeping micellar electrokinetic chromatography for the rapid and sensitive determination of zolpidem and its metabolites in human plasma.

Despite being one of the most widely prescribed hypnotic agents, zolpidem (Z) has raised increasing concerns due to its associated adverse effects and potential misuse, warranting closer monitoring. This study presents a highly sensitive and rapid cation-selective exhaustive injection and sweeping micellar electrokinetic chromatography (CSEI-sweeping-MEKC) method for the simultaneous determination of zolpidem and its major metabolites, zolpidem-6-carboxylic acid (Z6) and zolpidem phenyl-4-carboxylic acid (Z4), in human plasma, achieving complete analysis within 5 min. The proposed method demonstrated good linearity (r ≥ 0.994) over the concentration range of 5.0-500 ng mL-1 for Z and 25-1000 ng mL-1 for Z6 and Z4. Intra-batch (n = 3) and inter-batch (n = 5) validation showed satisfactory precision and accuracy, with relative error (RE) values ranging from -6.5% to 13.0%. The relative standard deviation (RSD) values were ≤8.6% for standard concentration levels, except at the LLOQ where they ranged from 6.1% to 15.9%. Application to clinical samples enabled monitoring of -Z and Z4 for up to 24 h following oral administration, demonstrating the feasibility of the proposed method for plasma analysis. Overall, this rapid and sensitive CE-based method provides a practical analytical platform for plasma monitoring and preliminary pharmacokinetic observation.