The detection of drug abuse in horseracing often requires knowledge of drug metabolism, especially if urine is the matrix of choice. In this study, equine liver/lung microsomes/S9 tissue fractions were used to study the phase I metabolism of eight drugs of relevance to equine drug surveillance (acepromazine, azaperone, celecoxib, fentanyl, fluphenazine, mepivacaine, methylphenidate and tripelennamine). In vitro samples were analyzed qualitatively alongside samples originating from in vivo administrations using LC-MS on a high resolution accurate mass Thermo Orbitrap Discovery instrument and by LC-MS/MS on an Applied Biosystems Sciex 5500 Q Trap.Using high resolution accurate mass full-scan analysis on the Orbitrap, the in vitro systems were found to generate at least the two most abundant phase I metabolites observed in vitro for all eight drugs studied. In the majority of cases, in vitro experiments were also able to generate the minor in vivo metabolites and sometimes metabolites that were only observed in vitro. More detailed analyses of fentanyl incubates using LC-MS/MS showed that it was possible to generate good quality spectra from the metabolites generated in vitro. These data support the suggestion of using in vitro incubates as metabolite reference material in place of in vivo post-administration samples in accordance with new qualitative identification guidelines in the 2009 International Laboratory Accreditation Cooperation-G7 (ILAC-G7) document.In summary, the in vitro and in vivo phase I metabolism results reported herein compare well and demonstrate the potential of in vitro studies to compliment, refine and reduce the existing equine in vivo paradigm.
A range of "Herbal High" products were tested for synthetic cannabinoids (cannabinomimetics) to qualitatively determine and compare their individual and relative content. Liquid chromatography-high resolution accurate mass spectrometry was used to rapidly screen samples for a range of cannabinomimetics using mono-isotopic masses derived from the elemental composition of target analytes. A screening database of over 140 compounds was rapidly created. This approach, combined with further tandem mass spectrometric experiments, also facilitated the detection and identification of compounds for which reference materials were not available. Previously reported cannabinomimetics, including JWH-018 and CP47,497 and its homologues, were detected in varying relative proportions along with several tentatively identified unreported cannabinomimetics. In some countries, the decision has been made to include these substances within their drug control legislation, and other countries are considering similar action. The currently applied drug screening techniques are unlikely to be effective in providing scientific evidence to support their identification in seized products. The application of high-resolution accurate mass spectrometry offers a solution. In addition, the technology provides a relatively simple and quick method for screening products, building substance databases, and even identifying novel substances using a combination of accurate mass derived elemental composition and fragment ions combined with fragmentation prediction software.
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