Determination and pharmacokinetic study of amlodipine in human plasma by ultra performance liquid chromatography-electrospray ionization mass spectrometry.

A novel, specific and sensitive ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed for the determination and pharmacokinetic study of amlodipine in human plasma. The analysis was carried out on an ACQUITY UPLC BEH C(18) column (50 mm x 2.1 mm, i.d., 1.7 microm) with gradient elution at a flow-rate of 0.35 ml/min. The mobile phase was water and acetonitrile under gradient conditions (both containing 0.3% formic acid) and nimodipine was used as the internal standard. Detection was performed on a triple-quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) mode via Turbo ion spray ionization (ESI). Linear calibration curves were obtained over the concentration range 0.15-16.0 ng/ml, with a lower limit of quantification of 0.15 ng/ml. The intra- and inter-day precision (R.S.D.) values were below 15% and the accuracy (R.E.) was -2.3% to 6.9% at all three QC levels. The method was used to support clinical pharmacokinetic studies of amlodipine in healthy volunteers following oral administration.