Bioequivalence study of bromhexine by liquid chromatography–electrospray ionization-mass spectrometry after oral administration of bromhexine hydrochloride tablets

A simple, sensitive and specific liquid chromatography–electrospray ionization-mass spectrometry method was developed for the quantitative determination of bromhexine in human plasma. Sample preparation involved simple liquid–liquid extraction. Simvastatin was used as internal standard. The separation of the analyte, internal standard and possible endogenous compounds were accomplished on a Shim-pack ODS column (150 mm × 4.6 mm i.d., 5 μm) with methanol–water (98:2, v/v) as mobile phase. Detection was performed in positive selected ion monitoring (SIM) mode at m/z 264.1 (for bromhexine) and m/z 441.7 (for IS). The method was validated over the range of 0.5–60 ng/mL and the results were acceptable. The method could offer the advantages of shorter run time (5.5 min) and lower LLOQ (0.5 ng/mL) with a decreased plasma volume requirement (250 μL) and it had been successfully applied to a bioequivalence study in healthy Chinese volunteers after single oral administration of 16 mg bromhexine.