A novel, sensitive and selective method of UPLC/MS-MS for rapid simultaneous determination of midodrine and its active metabolite desglymidodrine in human plasma: Application to support bioequivalence study in healthy human volunteers.

A specific, rapid, sensitive and selective ultra-performance liquid chromatography - tandem mass spectrometry has been developed for the simultaneous determination of midodrine and desglymidodrine in human plasma. The analytes and its deuterated analogs were quantitatively extracted from 100μL of human plasma by solid phase extraction technique. Separation of analytes was achieved on the Waters Acquity UPLC BEH C18 (50×2.1mm, 1.7μm) column using acetonitrile-4.0mM ammonium formate, pH 2.5(90:10, v/v) as mobile phase. The protonated analytes were quantified by selected reaction monitoring in the positive ionization mode by triple quadrupole mass spectrometer. The calibration plots were linear over the concentration range of 0.050-50.0ng/mL. The intra-batch and inter-batch precision (%CV) across quality control levels was <4.0 and the% mean relative recovery was ≥96%. Various other parameters like stability in different conditions; matrix effect and reproducibility of the method were performed in accordance with the guidelines specified by the USFDA for bioanalytical method development and validation. The developed method was successfully administered to the pharmacokinetics study of 5 mg midodrine tablet in 12 healthy subjects. Reproducibility of assay was proved by reanalysis of 48 incurred samples.