Simultaneous determination of dextromethorphan, dextrorphan and doxylamine in human plasma by HPLC coupled to electrospray ionization tandem mass spectrometry: Application to a pharmacokinetic study - Donato, J. L.; Koizumi, F.; Pereira, A. S.; Mendes, G. D.; De Nucci, Gilberto (Journal of Chromatography B, Analytical Technologies in the Biomedical and Life Sciences, 2012)