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 C18 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 (AUC0–96) 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 Cmax were (8.66 ± 1.15), (19.17 ± 4.13) ng/ml, respectively; apparent volume of distribution (Vd) were (1749 ± 964), (2480 ± 2212) L, respectively; time to Cmax (Tmax) were (2.8 ± 1.2), (3.0 ± 0.9) h, respectively; elimination half-life (t1/2β) 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: (Cmax) ss, (15.04 ± 2.27) ng/ml; (Tmax) ss, (2.38 ± 0.92) h; (Cmin) ss, (3.83 ± 0.94) ng/ml; Cav, (7.05 ± 1.54) ng/ml; DF, (1.62 ± 0.26); AUCss, (169.19 ± 36.87) ng · ml–1 · h.