Commercially available methylphenidate (MPH) exists as a racemic mixture composed of the d- and l-threo enantiomers. Various pharmacokinetic studies of MPH have shown a greater pharmacological potency of the d-threo enantiomer. Furthermore, it was deduced that the stereoselective cleavage of MPH to produce ritalinic acid (RA) by human carboxylesterase results in a higher oral bioavailability of the d-threo enantiomer. As a requirement for pharmaceutical regulation authorities, efforts have been made to determine the differential biological distribution of d- and l-threo MPH and RA enantiomers. In support of these efforts, numerous analytical procedures have been developed for the chiral separation and quantification of MPH enantiomers in a variety of biological matrices. The available methodologies accomplish the enantioseparation and quantification of MPH using gas chromatography, liquid chromatography or capillary electrophoretic techniques coupled with a variety of detectors. The current review discusses the technical procedures involved, and the sensitivity and selectivity of these assays.

High-throughput liquid chromatography with tandem mass spectrometric detection (LC-MS/MS) methodology for the determination of methamphetamine (METH), amphetamine (AMP), 4-hydroxymethamphetamine (4-OH-METH), and 4-hydroxyamphetamine (4-OH-AMP) was developed and validated using simple trichloroacetic acid sample treatment. The method was validated in rat serum, brain, and testis. Lower limits-of-quantitation (LOQ) for METH and AMP were 1 ng·mL-1 using positive ion electrospray tandem mass spectrometry (MS/MS). The accuracy of the method was within 25% of the actual values over a wide range of analyte concentrations. The within-assay precision was better than 12% (coefficient of variation). The method was linear over a wide dynamic range (0.3-1000 ng·mL-1). Quantitation was possible in all 3 matrices using only serum standards because of minimal matrix-associated ion effects or the use of an internal standard. Finally, the LC-MS/MS method was used to determine serum, brain, and testis METH and AMP concentrations during a subcutaneous infusion (5.6 mg kg-1 day-1) of METH in rats. Concentrations of 4-OH-AMP and 4-OH-METH were below the LOQ in experimental samples. The bias introduced by using serum calibrators for the determination of METH and AMP concentrations in testis and brain was less than 8% and insignificant relative to the interanimal variability.

Revised and Expanded Handbook Provides Comprehensive Introduction and Complete Instruction for Sample Preparation in Vital Category of Bioanalysis Following in the footsteps of the previously published Handbook of LC-MS Bioanalysis, this book is a thorough and timely guide to all important sample preparation techniques used for quantitative Liquid Chromatography–Mass Spectrometry (LC-MS) bioanalysis of small and large molecules. LC-MS bioanalysis is a key element of pharmaceutical research and development, post-approval therapeutic drug monitoring, and many other studies used in human healthcare. While advances are continually being made in key aspects of LC-MS bioanalysis such as sensitivity and throughput, the value of research/study mentioned above is still heavily dependent on the availability of high-quality data, for which sample preparation plays the critical role. Thus, this text provides researchers in industry, academia, and regulatory agencies with detailed sample preparation techniques and step-by-step protocols on proper extraction of various analyte(s) of interest from biological samples for LC-MS quantification, in accordance with current health authority regulations and industry best practices. The three sections of the book with a total of 26 chapters cover topics that include: Current basic sample preparation techniques (e.g., protein precipitation, liquid-liquid extraction, solid-phase extraction, salting-out assisted liquid-liquid extraction, ultracentrifugation and ultrafiltration, microsampling, sample extraction via electromembranes) Sample preparation techniques for uncommon biological matrices (e.g., tissues, hair, skin, nails, bones, mononuclear cells, cerebrospinal fluid, aqueous humor) Crucial aspects of LC-MS bioanalytical method development (e.g., pre-analytical considerations, derivation strategies, stability, non-specific binding) in addition to sample preparation techniques for challenging molecules (e.g., lipids, peptides, proteins, oligonucleotides, antibody-drug conjugates) Sample Preparation in LC-MS Bioanalysis will prove a practical and highly valuable addition to the reference shelves of scientists and related professionals in a variety of fields, including pharmaceutical and biomedical research, mass spectrometry, and analytical chemistry, as well as practitioners in clinical pharmacology, toxicology, and therapeutic drug monitoring.

While ketamine is traditionally administered for anesthesia or pain management, illicit usage is often seen in forensic cases either as a recreational drug or as a tool in drug-facilitated sexual assault. Xylazine is an anesthetic agent used in veterinary medicine and does not have FDA approval for use in humans. However, it has recently been observed as a cutting agent in heroin. Post-mortem specimens present many challenges when it comes to toxicological analysis. Due to compound degradation and decomposition factors, analytes present at trace levels may be missed in blood and urine. Hair, bone, and insects have recently been investigated as alternative matrices for postmortem analysis due to their increased durability compared to more traditional matrices. However, this durability increases the difficulties in extracting and isolating compounds of interest from these matrices via traditional extraction and chromatography methods. These methods require lengthy extraction times and extensive cleanup steps in order to obtain samples suitable for analysis. Utilizing multiple instrumentation combinations, analysts are able to detect compounds at trace levels. Through the use of multidimensional chromatography, several time-consuming extraction steps can be eliminated while still retaining the ability of trace level detection and quantitation. Using Waters Oasis® HLB PRiME solid phase extraction cartridges using a methanol pH10 loading and an acetonitrile pH3 elution, a solvent extraction yielded linear dynamic ranges of 2pg/mL-1ng/mL and 5pg/mL-1ng/mL for xylazine and ketamine respectively. Rat specimens utilized in this project were treated as per an Institutional Animal Care and Use Committee (IACUC) protocol. The test rodents received an acute dosage of 2mg/mL of xylazine and 24mg/mL of ketamine approximately half an hour prior to death. The 14 test samples were placed outside directly on the ground at the Boston University Forensic Anthropology Outdoor Research Facility (Holliston, MA, U.S.A.) for a period of 6 months. A 15th rat was kept in -20°C until analysis to serve as a Time=0 sample. The outdoor samples were recovered and de-fleshed along with the Time=0 sample manually. Drug-free hair samples were donated anonymously as per Internal Review Board (IRB) protocols.

No treatment that would completely stop the progression of Alzheimer's disease has not been found yet. Recently used tacrine showed good results in the treatment of Alzheimer's disease, however long-term use led to chronic hepatotoxicity due to its metabolites. This master thesis deals with the compound 7-phenoxytacrine, one of the promising tacrine derivatives, which is one of the candidates for potential use in the therapy of Alzheimer's disease. Due to the formation of hepatotoxic metabolites of tacrine after the biotransformation in human liver, it appears necessary to identify the emerging metabolites of 7-phenoxytacrine molecule. Within this master's thesis in vitro biotransformation study of 7-phenoxytacrine using human liver microsomes was performed. High performance liquid chromatography with tandem mass spectrometry was used to determine the parent substance and the seventeen 7-phenoxytacrine metabolites. The analytical method showed the formation of six monohydroxylated and eleven dehydroxylated metabolites of 7-phenoxytacrine. Thus, we concluded that hydroxylation is the major metabolic reaction after in vitro microsomal biotransformation. In addition to the identification of metabolites, a quantification and microsomal stability study, including the determination of the amount of...

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19517号 / 理博第4177号 / 新制||理||1600(附属図書館) / 32553 / 京都大学大学院理学研究科化学専攻 / (主査)教授 藤井 紀子, 教授 三木 邦夫, 教授 杉山 弘 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19752号 / 工博第4207号 / 新制||工||1649(附属図書館) / 32788 / 京都大学大学院工学研究科合成・生物化学専攻 / (主査)教授 濵地 格, 教授 梅田 眞郷, 教授 跡見 晴幸 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第20793号 / 医博第4293号 / 新制||医||1025(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 妻木 範行, 教授 鈴木 茂彦, 教授 瀬原 淳子 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

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