RESUMEN
In the present study, a fast, sensitive and robust method to quantify dextromethorphan, dextrorphan and doxylamine in human plasma using deuterated internal standards (IS) is described. The analytes and the IS were extracted from plasma by a liquid-liquid extraction (LLE) using diethyl-ether/hexane (80/20, v/v). Extracted samples were analyzed by high performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). Chromatographic separation was performed by pumping the mobile phase (acetonitrile/water/formic acid (90/9/1, v/v/v) during 4.0min at a flow-rate of 1.5 mL min⻹ into a Phenomenex Gemini® C18, 5 µm analytical column (150 × 4.6 mm i.d.). The calibration curve was linear over the range from 0.2 to 200 ng mL⻹ for dextromethorphan and doxylamine and 0.05 to 10 ng mL⻹ for dextrorphan. The intra-batch precision and accuracy (%CV) of the method ranged from 2.5 to 9.5%, and 88.9 to 105.1%, respectively. Method inter-batch precision (%CV) and accuracy ranged from 6.7 to 10.3%, and 92.2 to 107.1%, respectively. The run-time was for 4 min. The analytical procedure herein described was used to assess the pharmacokinetics of dextromethorphan, dextrorphan and doxylamine in healthy volunteers after a single oral dose of a formulation containing 30 mg of dextromethorphan hydrobromide and 12.5mg of doxylamine succinate. The method has high sensitivity, specificity and allows high throughput analysis required for a pharmacokinetic study.
Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Dextrometorfano/sangre , Dextrorfano/sangre , Doxilamina/sangre , Espectrometría de Masa por Ionización de Electrospray/métodos , Adolescente , Adulto , Dextrometorfano/farmacocinética , Dextrorfano/farmacocinética , Doxilamina/farmacocinética , Femenino , Humanos , Masculino , Persona de Mediana Edad , Sensibilidad y Especificidad , Espectrometría de Masas en Tándem/métodos , Adulto JovenRESUMEN
To answer the question, "Is this death due to a drug overdose?" requires at least that the drug be unequivocally identified and a blood concentration reliably determined. The approach taken in this case as standard addition technique and use of three different chromatographic techniques-high performance liquid chromatography (HPLC), high performance thin-layer chromatography (HP-TLC) and gas chromatography/mass spectrometry (GC/MS). Each of the chromatographies was carried out on the same extract by splitting the residue three ways. HPLC provided a quantitative result which was 1.2 mg/L in blood and HP-TLC and GC/MS confirmed this result with additional quantitative data, information about two metabolites (nordoxylamine and dinordoxylamine) and conclusive identification. Blood nordoxylamine was 0.52 mg/L and doxylamine plus metabolites in urine was 25 mg/L.