Pharmacokinetic Study of Miltefosine in Rat Plasma by UPLC-MS/MS

Miltefosine is a new oral drug to treat leishmaniasis, with relatively high efficacy rates reported for treatment of New World cutaneous, mucocutaneous, and visceral leishmaniasis. In this work, a sensitive and selective ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for determination of miltefosine in rat plasma was developed and validated. After addition of diazepam as an internal standard (IS), protein precipitation by acetonitrile-methanol (9:1, v/v) was used to prepare samples. Chromatographic separation was achieved on a UPLC BEH C18 column (2.1 mm x100 mm, 1.7 mu m) with 0.1% formic acid and methanol as the mobile phase with gradient elution. An electrospray ionization source was applied and operated in positive ion mode; multiple reactions monitoring (MRM) mode was used for quantification using target fragment ions m/z 408.2 -> 86.1 for miltefosine, and m/z 285.1 -> 193.1 for IS. Calibration plots were linear throughout the range 10-4000 ng/mL for miltefosine in rat plasma. Mean recoveries of miltefosine in rat plasma ranged from 86.7% to 96.4%, matrix effect of miltefosine in rat plasma ranged from 99.2% to 110.2%. RSD of intra-day and inter-day precision were both < 7%. The accuracy of the method was between 93.7% and 105.2%. The method was successfully applied to pharmacokinetic study of miltefosine after either oral or intravenous administration.