Quantitative Analysis of Naltrexone and 6β-Naltrexol in Human, Rat, and Rabbit Plasma by Liquid Chromatography-Electrospray Ionization Tandem Mass Spectrometry with Application to the Pharmacokinetics of Depotrex® in Rabbits

To improve the analysis of naltrexone and its primary metabolite 613-naltrexol, a sensitive and specific method for the analysis of subnanogram-per-milliliter concentrations of these analytes in human, rat, and rabbit plasma was developed utilizing liquid chromatography (LC) coupled to electrospray ionization (ESI) tandem mass spectrometry (MS-MS). Plasma samples were extracted utilizing a liquid-liquid extraction technique.