Determination of zolmitriptan and its primary metabolite, n-desmethy-zolmitriptan, in rat plasma by LC-MS-MS

The objective of this work was to develop a simple, cost effective, rugged and rapid method for the simultaneous estimation of zolmitriptan (ZP) and its active metabolite n-desmethy-zolmitriptan (DZP) in rat plasma to meet the requirement for biological sample analysis. The simple liquid-liquid extraction employed in the present work gave consistent and reproducible recoveries for both the analytes. A mixture of methanol-20 mM ammonium acetate-formic acid (60:40:0.1, v/v/v) was used as mobile phase at a flow rate of 0.3 mL/min. The temperature of column and autosampler were maintained at 40 and 4°C, respectively. The chromatographic run time of each sample was 3.0 min. The limit of quantification was low enough to monitor at least four half-lives of ZP and DZP concentrations with good intra-assay and inter-assay reproducibility for the quality controls. According to the results of all the validation parameters, the method can also be useful for pharmacokinetics study of ZP and for therapeutic drug monitoring in humans with the desired precision and accuracy.