Identification and quantitation of mifepristone and its N-demethyl metabolite in the plasma of an aborted fetus by liquid chromatography-quadrupole-time-of-flight-mass spectrometry (LC-Q-TOFMS) and ultra-performance liquid chromatography- tandem mass spectrometry (UPLC-MS-MS)

Mifepristone, also known as RU 486, is a derivative of norethindrone, a synthetic 19-nor-steroid; it acts as an antagonist to progestational and glucocorticoid functions by its binding to progesterone as well as glucocorticoid receptors [1]. Mifepristone is useful for terminating early pregnancy and for emergency contraception [1–4]. Mifepristone is approved in the US, EU countries, Israel, and China, but is not approved in Japan. In Japan, mifepristone has been ‘privately’ or secretly imported; the Ministry of Health, Labour and Welfare warned about its private import in 2004 because of possible complications, e.g., massive hemorrhaging [5]. Despite the warning, it has still been imported and used. It is, thus, important to detect mifepristone and its metabolites with high sensitivity. Several analytical methods have been reported for the measurement of mifepristone, such as the radioimmunoassay [6, 7], the radioreceptor assay [8, 9], voltammetry [10] and high performance liquid chromatography (LC) with an ultraviolet detector [11–17]. Recently, LC– tandem mass spectrometry (MS/MS) [18, 19] has been applied to detect and identify mifepristone and its metabolites from body fluids. In this Letter, we describe the determination of mifepristone and its metabolite in a plasma sample of an aborted fetus using a novel LC–quadrupole–time-of-flight– mass spectrometer (Q–TOFMS) with high sensitivity and specificity and an ultra-performance liquid chromatography–tandem mass spectrometer (UPLC–MS–MS). A woman in her twenties consulted an ER due to her poor health conditions; she then confessed her delivery and that she discarded the dead fetus. She also admitted that she had administered mifepristone and misoprostol prior to her delivery, although the time of administration and the amounts of the compounds were not clear. Around one day after delivery, autopsy of the fetus was performed. Autopsy findings were as follows: a male fetus whose height and weight were 30 cm and 505 g, respectively. No apparent injuries or malformations were observed. A cephalic hematoma-like finding was obtained. The lungs seemed liver-like, although histopathological observations detected some alveolar enlargement. Based on the above findings, the possibility that the fetus had been alive at the delivery was not fully excluded. The fetus was estimated to be at approximately 20–24 weeks gestation. Mifepristone and misoprostol were purchased from Sigma (St. Louis, MO, USA); N-demethyl mifepristone and alfaxalone were from Toronto Research Chemicals (Ontario, Canada) and Tocris (Bristol, UK), respectively. Drug free plasma was purchased from Tennessee Blood Services (Memphis, TN, USA). Other chemicals used were of the highest purity commercially available. A plasma specimen was collected from the femoral blood of the fetus. Mifepristone and its metabolites were analyzed based on the method by Homer et al. [19] with appropriate modifications. Screening of mifepristone and quantitation of the drug and its metabolites by UPLC–MS–MS were employed on an ACQUITY UPLC-TQD system (Waters, & Akira Ishii akishii@med.nagoya-u.ac.jp