Identification and quantitation of xenobiotics by 1H NMR spectroscopy in poisoning cases

1H Nuclear Magnetic Resonance: A Future Approach to the Metabolic Profiling of Psychedelics in Human Biofluids?

While psychedelics may have therapeutic potential for treating mental health disorders such as depression, further research is needed to better understand their biological effects and mechanisms of action when considering the development of future novel therapy approaches. Psychedelic research could potentially benefit from the integration of metabonomics by proton nuclear magnetic resonance (1H NMR) spectroscopy which is an analytical chemistry-based approach that can measure the breakdown of drugs into their metabolites and their metabolic consequences from various biofluids. We have performed a systematic review with the primary aim of exploring published literature where 1H NMR analysed psychedelic substances including psilocin, lysergic acid diethylamide (LSD), LSD derivatives, N,N-dimethyltryptamine (DMT), 5-methoxy-N,N-dimethyltryptamine (5-MeO-DMT) and bufotenin. The second aim was to assess the benefits and limitations of 1H NMR spectroscopy-based metabolomics as a tool in psychedelic research and the final aim was to explore potential future directions. We found that the most current use of 1H NMR in psychedelic research has been for the structural elucidation and analytical characterisation of psychedelic molecules and that no papers used 1H NMR in the metabolic profiling of biofluids, thus exposing a current research gap and the underuse of 1H NMR. The efficacy of 1H NMR spectroscopy was also compared to mass spectrometry, where both metabonomics techniques have previously shown to be appropriate for biofluid analysis in other applications. Additionally, potential future directions for psychedelic research were identified as real-time NMR, in vivo 1H nuclear magnetic resonance spectroscopy (MRS) and 1H NMR studies of the gut microbiome. Further psychedelic studies need to be conducted that incorporate the use of 1H NMR spectroscopy in the analysis of metabolites both in the peripheral biofluids and in vivo to determine whether it will be an effective future approach for clinical and naturalistic research.

Quantitative Nuclear Magnetic Resonance Spectroscopic Analysis of Two Commonly Used Gastrointestinal Tract Drugs

Two fast and precise quantitative nuclear magnetic resonance spectroscopic methods (qNMR) were established and evaluated for the determination of ondansetron (OND) and omeprazole (OMP) in bulk drugs and their pharmaceutical dosage forms. NMR spectra were established using dimethylsulfoxide (DMSO-d6) as a solvent and phloroglucinol as the internal standard. Proton NMR signals at 3.743, 3.811, and 5.670 ppm were used for quantitative monitoring purposes corresponding to OND, OMP, and phloroglucinol, respectively. In this study, the methods linearity, accuracy, limit of quantification, limit of detection, stability, and precision were validated as per International Conference on Harmonization (ICH) guidelines. Linearity ranges were 0.3-10 mg for OND and 1-10 mg for OMP. The student t-test and F-test were used for statistical evaluation. Herein, the proposed methods are useful and can be a successful practical appliance for OND and OMP determination in drug substances and their dosage forms.

NMR spectroscopy reveals acetylsalicylic acid metabolites in the human urine for drug compliance monitoring

Cardiovascular disease is the leading cause of morbidity and mortality worldwide. Long-term use of antiplatelet drugs is a well-studied therapy for the prevention of cardiovascular death. Ensuring compliance with lifelong administration of antiplatelet drugs, in particular acetylsalicylic acid, is one of the challenges of such therapy. The aim of this study is to explore the possibility of using nuclear magnetic resonance spectroscopy to identify acetylsalicylic acid metabolites in urine and to search for characteristic markers that could be used to detect patient compliance with long-term acetylsalicylic acid treatment.

Method validation and determinations of levofloxacin, metronidazole and sulfamethoxazole in an aqueous pharmaceutical, urine and blood plasma samples using quantitative nuclear magnetic resonance spectrometry

Selective, rapid and accurate quantitative proton nuclear magnetic resonance (qHNMR) method for the determination of levofloxacin, metronidazole benzoate and sulfamethoxazole in aqueous solutions was developed and validated. The method was successfully applied to the determinations of the drugs and their admixtures in pharmaceutical, urine and plasma samples. Maleic acid and sodium malate were used as internal standards. Effect of temperature on spectral measurements was evaluated. Linear dynamic ranges of 0.50-68.00, 0.13-11.30 and 0.24-21.00 mg per 0.60 mL solution were obtained for levofloxacin, metronidazole benzoate and sulfamethoxazole, respectively. Average recovery % in the range of 96.00-104.20 ± (0.17-2.91) was obtained for drugs in pure, pharmaceutical, plasma and urine samples. Inter and intra-day analyses gave average recoveries % in the ranges 96.10-98.40 ± (1.68-2.81) and 96.00-104.20 ± (0.17-2.91), respectively. Instrumental detection limits ≤0.03 mg per 0.6 mL were obtained for the three drugs. Developed method has demonstrated high performance characteristics for analyzing investigated drugs and their admixtures. Student t-test at 95% confidence level revealed insignificant bias between the real and measured contents of investigated drugs in pure, pharmaceutical, urine and plasma samples and its admixtures. Application of the statistical F-test revealed insignificant differences in precisions between the developed method and arbitrary selected reference methods.

Proton nuclear magnetic resonance spectroscopic determination of ethanol-induced formation of ethyl glucuronide in liver

Ethyl glucuronide (ethyl-beta-D-6-glucosiduronic acid, EtG), a unique metabolite of ethanol, has received much recent attention as a sensitive and specific biological marker of ethanol consumption. Formed in the liver via conjugation of ethanol with activated glucuronate, EtG remains detectable in serum, plasma, and hair for days after ethanol abuse. Thus far, gas chromatography-mass spectrometry and enzyme-linked immunosorbent assays have been developed to detect trace quantities of EtG for forensic purposes, but reports of the nuclear magnetic resonance (NMR) properties of EtG have been scarce. Herein we present the first report of EtG determination using proton NMR spectroscopy. We collected 700-MHz proton spectra of liver extracts from rats treated with a 4-day binge ethanol protocol (average ethanol dose: 8.6g/kg/day). An unexpected signal (triplet, 1.24 ppm) appeared in ethanol-treated liver extracts but not in control samples; based on chemical shift and multiplicity, we suspected EtG. We observed quantitative hydrolysis of the unknown species to ethanol while incubating our samples with beta-glucuronidase, confirming that the methyl protons of EtG were responsible for the triplet at 1.24 ppm. This study demonstrates that proton NMR spectroscopy is capable of detecting EtG and that future NMR-based metabolomic studies may encounter this metabolite of ethanol.

Application of nuclear magnetic resonance spectroscopy for quantitative analysis of miconazole, metronidazole and sulfamethoxazole in pharmaceutical and urine samples

Specific, accurate and precise NMR methods were developed for determining miconazole, metronidazole and sulfamethoxazole antibiotic drugs in authentic, pharmaceutical and urine samples. Proton nuclear magnetic resonance spectroscopy (1H NMR) with maleic acid as an internal standard and DMSO-d6 as NMR solvent were used. 1H NMR signals at 9.0, 8.06, 7.50 and 6.26 ppm corresponding to miconazole, metronidazole, sulfamethoxazole and maleic acid were respectively used for calculating the concentrations of drugs per unit dose. Average percent recoveries of (97.54-101.10), (98.06-100.46) and (97.83-102.83) with average uncertainties of 1.02, 0.45 and 0.86 were respectively obtained for determining authentic samples of miconazole, metronidazole and sulfamethoxazole in the concentration range of 0.92-170 mg/0.6 ml DMSO-d6. In pharmaceutical formulations and urine samples, average percent recoveries in the ranges of 97.50-101.33 and 94.46-100.86 were respectively obtained. Relative standard deviations (R.S.D.)<or=2.68 were obtained for analyzing the three drugs in authentic, pharmaceutical and urine samples. Admixtures of the three drugs in authentic, pharmaceutical and urine samples were analyzed. Good precisions (0.79-2.99%) and recoveries (93.40-104.97%) were obtained indicating the high selectivity and resolving power of the developed NMR methods and no needs for separation steps. Applying statistical Student t-test revealed insignificant difference between the real and measured contents at the 95% confidence level. F-test revealed insignificant difference in precisions between the developed NMR methods and HPLC methods reported for analyzing miconazole, metronidazole and sulfamethoxazole.

Determination of glyphosate in biological fluids by 1H and 31P NMR spectroscopy

Identification of glyphosate in four cases of poisoning, using nuclear magnetic resonance spectroscopy of biological fluids is reported. It has been performed by using a combination of 1H and 31P NMR analyses. Characterization of the N-(phosphonomethyl) glycine herbicide was achieved by chemical shift considerations and coupling constant patterns: CH2-(P) presents specific resonance at 3.12 ppm and appears as a doublet with a H-P characteristic coupling constant of 12.3 Hz. Moreover, resonances due to isopropylamine were present, confirming the ingestion of the considered trade formulation. After a calibration step, quantitation was performed by 1H and 31P NMR spectroscopy. The benefit and reliability of NMR investigations of biological fluids are discussed, particularly when the clinical picture is quite confusing.

??-Hydroxybutyrate

Laboratory detection of gamma-hydroxybutyrate (GHB) has been published as early as the 1960s. However, wide-scale use of GHB during the 1990s has led to the development of current analytic methods to test for GHB and related compounds. Detection of GHB and related compounds can be clinically useful in confirming the cause of coma in an overdose patient, determining its potential role in a postmortem victim, as well as evaluating its use in a drug-facilitated sexual assault victim. Analytical method sensitivity must be known in order to determine the usefulness and clinical application. Most laboratory cut-off levels are based on instrument sensitivity and will not establish endogenous versus exogenous GHB levels. Interpretation of GHB levels must include a knowledge base of endogenous GHB, metabolism of GHB and related compounds, as well as postmortem generation. Due to potential analytical limitations in various GHB methods, it is clinically relevant to specifically request for GHB as well as related GHB compounds if they are also in question. Various storage conditions (collection time, types of containers, use of preservatives, storage temperature) can also affect the analysis and interpretation of GHB and related compounds.