Determination of azelnidipine by LC-ESI-MS and its application to a pharmacokinetic study in healthy Chinese volunteers

A simple, rapid and sensitive high performance liquid chromatography-electrospray ionization-mass spectrometry (HPLC-ESI-MS) assay for determination of azelnidipine in human plasma using perospirone as the internal standard (IS) was established. After adjustment to a basic pH with sodium hydroxide solution, plasma samples were extracted with diethyl ether and separated on a C-18 column with a mobile phase of methanol-5 mM ammonium acetate solution (90:10, v/v). The lower limit of quantification (LLOQ) was 0.20 ng/ml. After administration of a single dose of azelnidipine 8 mg and 16 mg, respectively; the area under the plasma concentration versus time curve from time 0 h to 96 h (AUC(0-96)) were (186 +/- 47) ng . ml(-1) . h, (429 +/- 145) ng . ml(-1) . h, respectively; clearance rate (CL/F) were (45.94 +/- 11.61), (42.11 +/- 14.23) L/h, respectively; peak plasma concentration C-max were (8.66 +/- 1.15), (19.17 +/- 4.13) ng/ml, respectively; apparent volume of distribution (V-d) were (1749 +/- 964), (2480 +/- 2212) L, respectively; time to C-max (T-max) were (2.8 +/- 1.2), (3.0 +/- 0.9) h, respectively; elimination half-life (t(1/2 beta)) were (22.8 +/- 2.4), (23.5 +/- 4.2) h, respectively; and MRT were (25.7 +/- 1.3), (26.2 +/- 2.2) h, respectively; The essential pharmacokinetic parameters after oral multiple doses (8 mg, q.d.) were as follows: (C-max) ss, (15.04 +/- 2.27) ng/ml; (T-max) ss, (2.38 +/- 0.92) h; (C-min) ss, (3.83 +/- 0.94) ng/ml; C-av,C- (7.05 +/- 1.54) ng/ml; DF, (1.62 +/- 0.26); AUCss, (169.19 +/- 36.87) ng . ml(-1) . h.