Determination of mildronate by LC-MS/MS and its application to a pharmacokinetic study in healthy Chinese volunteers.

A simple, rapid and accurate liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the determination of mildronate in human plasma. Following a simple protein precipitation with methanol, the analyte was separated on a C(18) column by isocratic elution with methanol and 10 mM ammonium acetate (55:45; v/v), and then analyzed by mass spectrometry in the positive ion MRM mode. Good linearity was achieved over a wide range of 0.01-20 microg/mL. The intra- and inter-batch precisions (as RSD, %) were less than 7.1%. The average extraction recovery was 87.5%. The method described above has been used, for the first time, to reveal the pharmacokinetics of mildronate injection in healthy subjects. After single intravenously administration of 250, 500 and 1000 mg mildronate, the elimination half-life (t(1/2)) were (5.56+/-1.55), (6.46+/-1.07) and (6.55+/-1.17) h, respectively. The Student-Newman-Keuls test results showed that peak plasma concentration (C(max)) and the area under the plasma concentration versus time curve from time 0 to 24h (AUC(0-24)) were both linearly related to dose. The pharmacokinetics of mildronate fitted the linear dynamic feature over the dose range studied. The essential pharmacokinetic parameters of multidoses administration intravenously (500 mg, b.i.d) were as follows: t(1/2) was (15.34+/-3.14) h; C(max) was (25.50+/-3.63) microg/mL; AUC(0-24) was (58.56+/-5.57) mgh/L. The t(1/2) and AUC of multidoses administration intravenously were different from those of single-dose administration significantly. These findings suggested that accumulation of mildronate in plasma occurred.