A Liquid Chromatography Tandem Mass Spectrometry Method for the Quantification of Tamsulosin: Application to a Pharmacokinetic Study in Healthy Human Subjects

A simple, rapid and sensitive high throughput liquid chromatographic method coupled with tandem mass spectrometry (LC–MS/MS) has been developed and validated to quantify tamsulosin in human plasma using tamsulosin D4 as internal standard (I.S). The analyte and internal standard were extracted from 300 μL plasma via solid phase extraction and were separated on a Kromasil C18 column (100 × 4.6 mm, 5 µ) with isocratic elution using acetonitrile: 5 mM ammonium formate (70: 30, v/v) containing 0.05 % formic acid as mobile phase. Tamsulosin was quantified using a triple quadruple mass spectrometer operated in multiple-reaction-monitoring (MRM) mode using positive electrospray ionization. The mass transitions m/z 409.2→228.0 and m/z 413.2→228.0 were used to measure tamsulosin and tamsulosin D4 respectively. The calibration curves were linear (r2 >0.99) over the concentration of 0.1-89.4 ng/mL, where the regression model (1/x2) was best fitted. The intra- and inter-day batches precision (%CV) and accuracy values were found to be within the assay variability limit as per the FDA guidelines. The validated method was successfully applied to a pharmacokinetic bioequivalence study in human volunteers and found selective, sensitive and robust in quantitative measurement of tamsulosin in plasma samples.