Abstract
A rapid and sensitive LC-MS-MS method for the determination of alverine (ALV) and its major metabolite, monohydroxy alverine (MHA), in human plasma using imipramine as an internal standard was developed and validated. The analytes were extracted from 0.5 mL aliquots of human plasma by solid phase extraction, using oasis cartridge. Chromatographic separation was carried on Thermo Gold C18 column (50 × 4.6 mm, 5 μ) at 30 °C, with isocratic mobile phase, a flow rate of 0.4 mL/min and a total run time of 3.5 min. Detection and quantification were performed using a mass spectrometer in the selected reaction-monitoring mode with positive electrospray ionization at m/z 282.3 → 91.11 for alverine, m/z 298.3 → 106.9 for mono-hydroxy-alverine, and m/z 281.0 → 86.0 for internal standard (IS) respectively. This assay was linear over a concentration range of 0.060-10 ng/mL with a lower limit of quantification of 0.060 ng/mL for both alverine and monohydroxy alverine. The coefficient of variation for the assay precision were <9.18% and <8.44%, the accuracy were >104.66% and >100.38% for alverine and monohydroxy alverine respectively. This method was successfully applied to a pharmacokinetic study after oral administration of alverine citrate 60 mg capsule in healthy male subjects.