Systematic evaluation of matrix effect and cross-talk-free method for simultaneous determination of zolmitriptan and N-desmethyl zolmitriptan in human plasma: a sensitive LC-MS/MS method validation and its application to a clinical pharmacokinetic study.

The objective of the present work was to carry out systematic evaluation to eliminate matrix effect owing to plasma phospholipids as observed during sample preparation and to develop a cross-talk-free sensitive, selective and rapid bioanalytical method for the simultaneous determination of zolmitriptan (ZT) and N-desmethyl zolmitriptan (DZT) in human plasma by liquid chromatography-tandem mass spectrometry using naratriptan as internal standard (IS). The analytes and IS were quantitatively extracted from 200 μL human plasma by solid phase extraction. No cross-talk was found between ZT and DZT having identical product ions. Quantitation was performed on a triple quadrupole mass spectrometer employing electrospray ionization technique, operating in multiple reaction monitoring and positive ion mode. The total chromatographic run time was 2.5 min. The method was fully validated for sensitivity, selectivity, specificity, linearity, accuracy, precision, recovery, matrix effect, dilution integrity and stability studies. The method was validated over a dynamic concentration range of 0.1-15 ng/mL for ZT and DZT. The method was successfully applied to a bioequivalence study of 2.5 mg ZT tablet formulation in 18 healthy Indian male subjects under fasting conditions. Assay reproducibility was assessed by reanalysis of 62 incurred samples.