A validated LC–MS/MS method for the quantification of amlodipine, bisoprolol, enalapril and enalaprilat—Application to pharmacokinetic study in healthy volunteers

Abstract

In this work, a highly sensitive and rapid liquid chromatography-tandem mass spectrometry (LC–MS/MS) method for the simultaneous determination of amlodipine (AML), bisoprolol (BIS) and enalapril maleate (ENA) in the presence of its metabolite enalaprilat (ENT) in real human plasma was developed and validated using felodipine, propranolol, ramipril, and captopril, as internal standards (IS), respectively. The prepared samples were chromatographed using Eclipse C18 column (4.6 × 100 mm, 5 μm) and the mobile phase was pumped in an isocratic mode consisting of acetonitrile: 0.01% formic acid (70:30, v/v) at a flow rate 0.7 mL min−1. The detection was achieved on an API 4500 triple quadrupole mass spectrometer using multiple reaction monitoring (MRM) mode in the positive electrospray ionization interface. Linearity was obtained over a concentration range of 0.1–10, 0.5–50, 5–500 and 1–100 ng/mL for AML, BIS, ENA and ENT respectively, by applying weighted leastsquares linear regression method (1/x2 ). The accuracy and sensitivity of the proposed method allowed its application to determine the pharmacokinetics of these analytes in human male volunteers following a single oral administration