A Sensitive and Reliable LC-MS/MS Method for the Determination of Ambroxol and its Application to a Pharmacokinetic Study in healthy Chinese Subjects

. In the present study, a sensitive and reliable liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and validated for assessment of ambroxol pharmacokinetics in human plasma sample according to FDA guidelines. Ambroxol and propranolol (internal standard, IS) were extract-ed from plasma samples using liquid-liquid extraction (LLE) with ethyl acetate. Chromatographic separation was achieved on a Luna C18column (2.0 mm x 150 mm, 5 mu m) using acetonitrile-0.1% formic acid water as the mobile phase at a flow rate of 0.6 mL/min under gradient elution procedure. Quantification was performed by using an electrospray ionization (ESI) source in the positive ion mode, and the multiple reaction monitoring (MRM) conversions of m/z 379.0 -> 263.9 for ambroxol, and m/z 260.1 -> 116.1 for IS were conducted. Correla-tion coefficients > 0.9966 were achieved for all the calibration curves with linear regression. The intra-day and inter-day precisions of ambroxol were 6.9-9.1% and 1.2-14.4%, respectively, while the corresponding accuracies were-2.4-2.8% with high extraction recovery and little matrix effect. The method developed in the current study was successfully applied to the evaluation of pharmacokinetic study of ambroxol in healthy Chinese volunteers after single oral administration of salbutamol/ambroxol fixed-dose combination granules (containing 15 mg ambroxol). Compared with the other literature available for human plasma, the current study possesses many advantages, e.g. high sensitivity (LLOQ of 0.100 ng/mL for ambroxol), low cost (small plasma volume of 100 mu L), and a short chromatographic run time (4.0 min per sample).