Interpreting γ-hydroxybutyrate concentrations for clinical and forensic purposes

Determination of endogenous GHB in ante-mortem whole blood, urine, and oral fluid by LC-MS/MS: The effect of different additives and storage conditions on the stability of GHB in blood

Two challenges in detecting γ-hydroxybutyric acid (GHB) intake are its endogenous presence and in vitro production after sampling. This study developed an LC-MS/MS method for selective GHB determination in human antemortem blood, urine, and oral fluid at endogenous concentrations. Furthermore, the stability of GHB in blood samples and its endogenous concentrations in samples taken under controlled circumstances were investigated. Samples were extracted in methanol/acetonitrile and processed by anion exchange solid-phase extraction. GHB was separated from structural isomers using a reversed-phase LC column with anion properties. The validated limit of quantification was 0.005 µg/mL in blood and 0.010 µg/mL in urine and oral fluid, at which the relative reproducibility standard deviation and bias were <15 %. The mean extraction recovery was ≥90 %. The average GHB concentration increased by 1.2 µg/mL in fluoride/citrate- preserved blood after 28 days of storage at 4°C; however, in fluoride/oxalate (FX)-preserved blood, the mean concentration increased by only 0.055 µg/mL. No change was observed at -20°C. In 105 randomly selected samples of FX-preserved blood collected for forensic antemortem toxicological analysis, all concentrations were <0.066 µg/mL, even after long-term storage at -20°C. In blood, urine, and oral fluid samples from a clinical study of GHB intake, endogenous baseline levels from 30 participants ranged from 0.0069-0.050, 0.024-0.38, and 0.034-0.93 µg/mL, respectively. These results demonstrate that the current cut-off level of 5 µg/mL for discriminating between endogenous and exogenous GHB in antemortem blood could be considerably lower for FX-preserved blood stored at -20°C.

Injector port acylation of γ-hydroxybutyrate (GHB): Condition optimisation, source adjustments, and characterisation of the derivatives

For several years, gas chromatography-mass spectrometry (GC-MS) has been used to identify gamma-hydroxybutyrate (GHB) in forensic toxicology cases. However, under injector port conditions GHB can dehydrate into gamma-butyrolactone (GBL). Therefore, it is important for GHB to undergo a derivatisation reaction before an analysis to avoid the production of GBL; various analytical methods have been developed for the analysis of GHB but very few methods use acylation as a form of derivatisation. This study explores the optimisation of injector port acylation of GHB to improve its detectability and thermostability. By utilising trifluoroacetic acid anhydride (TFAA) and heptafluorobutyric acid anhydride (HFBA) to enhance the chromatography and mass spectra of the resulting derivatives. As a result, both reagents improved the detectability of GHB, with TFAA producing more predominant peaks within the chromatogram and HFBA offering a more complex mass spectrum. The optimal injector temperature was found to be 240 °C for both reagents, which significantly increased the derivatisation yields. These results demonstrate the effectiveness of injector port acylation as an alternative derivatisation route for GHB related drug cases.

Single hair analysis for gamma-hydroxybutyric acid-Method optimization, validation, and application

As gamma-hydroxybutyric acid (GHB) underlies fast metabolization, its determination from hair may presumably offer a detection window superior to that of body fluids. Due to the wide range of endogenous concentration levels, the evidence of an exogenous ingestion is challenging. As already shown for other drugs, the temporal resolution obtained by applying single hair microanalysis provides further information. Therefore, a method for the extraction and quantification of GHB in 2-mm hair segments (seg) was optimized and validated (limit of detection [LOD]: 2.5 pg/seg, lower limit of quantification [LLOQ]: 5 pg/seg), and five single hairs were examined, each for three non-users and for three (alleged) users. A major challenge was the choice of appropriate extraction tubes without remains of GHB. In two samples from non-users, GHB could not or could only be detected in trace amounts. In the third sample, concentrations between the LOD and 31.1 pg/seg (mean: 9.5, median: 8.4; each pg/seg) were detected with decreasing values towards the tips. In two samples of persons with assumed GHB intake, maximum concentrations of 6.8 and 30.7 pg/seg were measured, but no significant concentration peaks indicating a single ingestion could be observed. The third sample showed concentrations of 7.6-55.2 pg/seg (mean: 28.8, median: 29.6; each pg/seg). In this case, the obtained profiles showing at least two reproducible concentration maxima between 20 and 40 mm point to an ingestion of GHB. The concentration profiles from single hairs were reproducible in each case, reflecting the concentration course of routine 1-cm segmental analysis. These are the first results published on GHB testing in segmented single hairs, and the results must be verified further.

A multicentre case series of analytically confirmed gamma-hydroxybutyrate intoxications in Western Australian emergency departments: Pre-hospital circumstances, co-detections and clinical outcomes

INTRODUCTION

Gamma-hydroxybutyrate (GHB) use is associated with high risk of accidental overdose. This study examined the pre-hospital circumstances, demographic characteristics and clinical outcomes of analytically confirmed GHB emergency department (ED) presentations in Western Australia (WA).

METHODS

This case series was conducted across three WA EDs involved in the Emerging Drugs Network of Australia, from April 2020 to July 2022. Patient demographics, pre-hospital drug exposure circumstances and ED presentation and outcome characteristics were collected from ambulance and hospital medical records of GHB-confirmed cases.

RESULTS

GHB was detected in 45 ED presentations. The median age was 34 years and 53.3% (n = 24) were female. Most patients arrived at the ED by ambulance (n = 37, 85.7%) and required immediate emergency care (Australasian Triage Score 1 or 2 = 97.8%). One-third of patients were admitted to intensive care (n = 14, 31.1%). Methylamphetamine was co-detected in 37 (82.2%) GHB-confirmed cases. Reduced conscious state was indicated by first recorded Glasgow Coma Scale of ≤8 (n = 29, 64.4%) and observations of patients becoming, or being found, 'unresponsive' and 'unconscious' in various pre-hospital settings (n = 28, 62.2%). 'Agitated' and/or 'erratic' mental state and behavioural observations were recorded in 20 (44.4%) cases.

DISCUSSION AND CONCLUSIONS

Analytically verified data from ED presentations with acute toxicity provides an objective information source on drug use trends and emerging public health threats. In our study, patients presenting to WA EDs with GHB intoxication were acutely unwell, often requiring intensive care treatment. The unexpectedly high proportion of female GHB intoxications and methylamphetamine co-ingestion warrants further exploration.

Deciphering survival strategies: Oxidative stress and microbial interplay in Eisenia fetida under tetracycline contamination

Soil contamination resulting from residual antibiotics presents a pressing need to understand the survival mechanisms of soil organisms in polluted environments. This study focused on Eisenia fetida, and tetracycline stress experiments were conducted in a controlled environment using sterile artificial soil. The stress concentration ranged from 0 to 600 mg/kg, and stress cycles lasted either 10 or 30 days. The objective of this study was to assess the effects of oxidative stress and the changes in microbial communities both within and outside the earthworms. A comprehensive mathematical model was developed to elucidate the responses of organisms following exposure to stress utilizing factor analysis, grey relational analysis, and hierarchical entropy weight analysis. Under tetracycline stress, the initial stage (1-3 days) exhibited a coordinated regulation of oxidative stress and microbial communities in the soil with the assistance of CAT and GPX enzymes. The subsequent stage (4-5 days) further emphasized the influence of soil microbial communities. A notable "feedback regulation" of soil microbial communities on oxidative stress was observed during the third stage (6-8 days). Earthworms maintained a metabolic balance in the fourth stage (9-10 days). In the long term, the stress-induced a self-detoxification mechanism within soil microbial communities, which collaborated with GPX to respond to oxidative stress.

Gamma-hydroxybutyrate (GHB), 1,4-butanediol (1,4BD), and gamma-butyrolactone (GBL) intoxication: A state-of-the-art review

γ-hydroxybutyrate (GHB) is synthesized endogenously from γ-aminobutyric acid (GABA) or exogenously from 1,4-butanediol (butane-1,4-diol; 1,4-BD) or γ-butyrolactone (GBL). GBL, and 1,4-BD are rapidly converted to GHB. The gastric absorption time, volume of distribution, and half-life of GHB are between 5 and 45 min, 0.49 ± 0.9 L/kg, and between 20 and 60 min, respectively. GHB and its analogues have a dose-dependent effect on the activation of GHB receptor, GABA-B, and GABA localized to the central nervous system. After ingestion, most patients present transient neurological disorders (lethal dose: 60 mg/kg). Chronic GHB consumption is associated with disorders of use and a withdrawal syndrome when the consumption is discontinued. GHB, GBL, and 1,4-BD are classified as narcotics but only the use of GHB is controlled internationally. They are used for drug facilitated (sexual) assault, recreational purposes, slamsex, and chemsex. To confirm an exogenous intake or administration of GHB, GBL, or 1-4-BD, the pre-analytical conservation is crucial. The antemortem cutoff doses for detection are 5 and 5-15 mg/L, with detection windows of 6 and 10 h in the blood and urine, respectively Control of GHB is essential to limit the number of users, abuse, associated risks, and death related to their consumption.

Urinary concentrations of GHB and its novel amino acid and carnitine conjugates following controlled GHB administration to humans

Gamma-hydroxybutyrate (GHB) remains a challenging clinical/forensic toxicology drug. Its rapid elimination to endogenous levels mainly causes this. Especially in drug-facilitated sexual assaults, sample collection often occurs later than the detection window for GHB. We aimed to investigate new GHB conjugates with amino acids (AA), fatty acids, and its organic acid metabolites for their suitability as ingestion/application markers in urine following controlled GHB administration to humans. We used LC-MS/MS for validated quantification of human urine samples collected within two randomized, double-blinded, placebo-controlled crossover studies (GHB 50 mg/kg, 79 participants) at approximately 4.5, 8, 11, and 28 h after intake. We found significant differences (placebo vs. GHB) for all but two analytes at 4.5 h. Eleven hours post GHB administration, GHB, GHB-AAs, 3,4-dihydroxybutyric acid, and glycolic acid still showed significantly higher concentrations; at 28 h only GHB-glycine. Three different discrimination strategies were evaluated: (a) GHB-glycine cut-off concentration (1 µg/mL), (b) metabolite ratios of GHB-glycine/GHB (2.5), and (c) elevation threshold between two urine samples (> 5). Sensitivities were 0.1, 0.3, or 0.5, respectively. Only GHB-glycine showed prolonged detection over GHB, mainly when compared to a second time- and subject-matched urine sample (strategy c).

Acute Sodium Oxybate Intoxication: A Case Report and Review of the Literature

PURPOSE

Despite a better safety profile than illicit γ-hydroxybutyric acid (GHB) and other GHB analogs, sodium oxybate continues to raise serious concerns regarding clinical safety. In this study, the authors report the case of near-fatal intoxication involving sodium oxybate-alcohol combination in a 40-year-old woman. In addition, a review of the literature on published cases of intoxication involving this pharmaceutical form of GHB was conducted. A 40-year-old woman was admitted to the intensive care unit in a coma after voluntary ingestion of 18 g of sodium oxybate and alcohol.

METHODS

The GHB plasma concentration was quantified to be 146 mg/L using liquid chromatography coupled with tandem mass spectrometry. An English literature search was performed using PubMed without any limiting period to identify all available scientific publications involving cases of sodium oxybate intoxication.

RESULTS

Six cases were identified. Five involved fatal intoxication cases, with GHB postmortem blood concentrations ranging from 11.5 to 3500 mg/L. One involved a nonfatal intoxication case with a GHB serum concentration of 569 mg/L 7 hours postingestion.

CONCLUSIONS

In the present case, the estimated elimination half-life was 154 minutes. The risk of acute poisoning seems to be high considering the pharmacokinetic properties of sodium oxybate. Physicians and toxicologists must take such properties into account.

Characteristics of analytically confirmed gamma-hydroxybutyrate (GHB) positive patients in the emergency department: presentation, poly-drug use, disposition and impact on intensive care resource utilisation

BACKGROUND

Gamma-hydroxybutyrate is a potent central nervous system depressant with a narrow recreational dose window and analytical detection time. We describe data relating to intoxicated patients presenting to emergency departments across metropolitan Adelaide who tested positive for gamma-hydroxybutyrate. This work was part of the Emergency Department Admission Blood Psychoactive Testing study.

METHODS

Over a 15-month period, patients presenting to four metropolitan emergency departments with symptoms of drug intoxication were enrolled in the study. The methodology involved the collection of demographic and clinical data and a de-identified blood sample which underwent comprehensive toxicological analysis. Gamma-hydroxybutyrate was determined using an acid-catalysed cyclisation followed by liquid-liquid extraction and gas chromatography-mass spectrometry. Data relating to samples positive for gamma-hydroxybutyrate were examined.

RESULTS AND DISCUSSION

A total of 1120 patients were enrolled between March 2019 and May 2020, 309 of whom were positive for gamma-hydroxybutyrate (27.6%). Of these, 256 (83%) were also positive for metamfetamine (methamphetamine). The most common clinical observation in gamma-hydroxybutyrate-positive patients was central nervous system depression (89%). There was a significant relationship between gamma-hydroxybutyrate status and sex; although males outnumbered females in absolute terms, a higher proportion of females (32%) tested positive for gamma-hydroxybutyrate than males (25%, P = 0.0155). Blood gamma-hydroxybutyrate concentrations ranged from 10 to 651 mg/L (0.096-6.2 mmol/L) and increasing gamma-hydroxybutyrate concentration correlated with severe toxicity. The presence of gamma-hydroxybutyrate had a significant impact on the patient discharge destination: the majority (69.2%) of gamma-hydroxybutyrate-positive patients were managed and discharged from the emergency department or their attached short stay wards. A significantly higher proportion of gamma-hydroxybutyrate-positive patients were admitted to the intensive care unit (28.2%) compared with gamma-hydroxybutyrate-negative patients (12.7%, chi-squared = 36.85, P <0 .001). Gamma-hydroxybutyrate positive cases accounted for 45.8% of all study-related intensive care unit admissions.

CONCLUSIONS

Gamma-hydroxybutyrate is commonly detected in illicit drug-related emergency department presentations and is detected disproportionately in the patient cohort who require intensive care unit level care.

New gamma-hydroxybutyric acid (GHB) biomarkers: Development and validation of a liquid chromatography-tandem mass spectrometry method for the determination of GHB amino acid, carnitine, and fatty acid conjugates in urine

Gamma-hydroxybutyric acid (GHB) represents an important drug in clinical and forensic toxicology, particularly in the context of drug-facilitated crimes. Analytically, GHB remains a major challenge given its endogenous occurrence and short detection window. Previous studies identified a number of potential interesting novel conjugates of GHB with carnitine, amino acids (AA, glutamate, glycine, and taurine), or fatty acids. As a basis for comprehensive studies on the suitability of these novel biomarkers, we developed and validated a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method in human urine. Additionally, already known markers 2,4-dihydroxy butyric acid (2,4-DHB), 3,4-DHB, glycolic acid, succinic acid, succinylcarnitine, and GHB glucuronide were included. The method was fully validated according to (inter)national guidelines. Synthetic urine proved suitable as a surrogate matrix for calibration. Matrix effects were observed for all analytes with suppression effects of about 50% at QC LOW, and approximately 20% to 40% at QC HIGH, but with consistent standard deviation of <25% at QC LOW and <15% at QC HIGH, respectively. All analytes showed acceptable intra- and inter-day imprecision of below 20%, except for inter-day variation of GHB taurine and FA conjugates at the lowest QC. Preliminary applicability studies proved the usefulness of the method and pointed towards GHB glycine, followed by other AA conjugates as the most promising candidates to improve GHB detection. FA conjugates were not detected in urine samples yet. The method can be used now for comprehensive sample analysis on (controlled) GHB administration to prove the usefulness of the novel GHB biomarkers.

Urinary Profile of Endogenous Gamma-Hydroxybutyric Acid and its Biomarker Metabolites in Healthy Korean Females: Determination of Age-Dependent and Intra-Individual Variability and Identification of Metabolites Correlated With Gamma-Hydroxybutyric Acid

Gamma-hydroxybutyric acid (GHB), used as a therapeutic and an illegal anesthetic, is a human neurotransmitter produced during gamma-aminobutyric acid (GABA) biosynthesis and metabolism. Potential biomarker metabolites of GHB intoxication have been identified previously; however, reference concentrations have not been set due to the lack of clinical study data. Urinary profiling of endogenous GHB and its biomarker metabolites in urine samples (n = 472) of 206 healthy females was performed based on differences in age and time of sample collection using liquid chromatography-tandem mass spectrometry following validation studies. The unadjusted and creatinine-adjusted urinary concentrations ranges were obtained after urinary profiling. The creatinine-adjusted concentrations of glutamic and succinic acids and succinylcarnitine significantly increased, whereas that of glycolic acid significantly decreased with advancing age. Significant inter-day variation of GABA concentration and intra-day variation of 3,4-dihydroxybutyric acid and succinylcarnitine concentrations were observed. The urinary concentrations of 2,4-dihydroxybutyric acid, succinic acid, and 3,4-dihydroxybutyric acid showed the highest correlation with that of GHB. Data from this study suggest population reference limits to facilitate clinical and forensic decisions related to GHB intoxication and could be useful for identification of biomarkers following comparison with urinary profiles of GHB-administered populations.

A Retrospective Metabolomics Analysis of Gamma-Hydroxybutyrate in Humans: New Potential Markers and Changes in Metabolism Related to GHB Consumption

GHB is an endogenous short-chain organic acid presumably also widely applied as a rape and knock out drug in cases of drug-facilitated crimes or sexual assaults (DFSA). Due to the endogenous nature of GHB and its fast metabolism in vivo, the detection window of exogenous GHB is however narrow, making it challenging to prove use of GHB in DFSA cases. Alternative markers of GHB intake have recently appeared though none has hitherto been validated for forensic use. UHPLC-HRMS based screening of blood samples for drugs of abuse is routinely performed in several forensic laboratories which leaves an enormous amount of unexploited data. Recently we devised a novel metabolomics approach to use archived data from such routine screenings for elucidating both direct metabolites from exogenous compounds, but potentially also regulation of endogenous metabolism and metabolites. In this paper we used UHPLC-HRMS data acquired over a 6-year period from whole blood analysis of 51 drivers driving under the influence of GHB as well as a matched control group. The data were analyzed using a metabolomics approach applying a range of advanced analytical methods such as OPLS-DA, LASSO, random forest, and Pearson correlation to examine the data in depth and demonstrate the feasibility and potential power of the approach. This was done by initially detecting a range of potential biomarkers of GHB consumption, some that previously have been found in controlled GHB studies, as well as several new potential markers not hitherto known. Furthermore, we investigate the impact of GHB intake on human metabolism. In aggregate, we demonstrate the feasibility to extract meaningful information from archived data here exemplified using GHB cases. Hereby we hope to pave the way for more general use of the principle to elucidate human metabolites of e.g. new legal or illegal drugs as well as for applications in more global and large scale metabolomics studies in the future.

Characteristics of patients with analytically confirmed γ-hydroxybutyric acid/γ-butyrolactone (GHB/GBL)-related emergency department visits in Taiwan

The recreational drug γ-hydroxybutyric acid (GHB) is a central nervous system depressant, and can produce euphoria at low doses. GHB is a controlled substance in Taiwan. However, the organic solvents γ-butyrolactone (GBL) and 1,4-butanediol (BD), which are unregulated, may be used as an alternative source of GHB. There is no clinical report of analytically confirmed GHB use in Taiwan. We retrospective reviewed the clinical characteristics from the medical charts between May 2017 and April 2020. The urine samples of patients presented to the emergency departments with drug-related complaints were sent for toxicological analysis. Patients with urine samples detected GHB >10 μg/mL by liquid chromatography/tandem mass spectrometry were included. Overall, 11 men and one woman with an average age of 35.3 ± 8.7 years were included. Most patients co-ingested amphetamine (n = 6) and initially presented with depressed consciousness levels (n = 7). One patient presented with out-of-hospital cardiac arrest and one with respiratory depression. All patients regained consciousness within 6 h of admission. All patients used GBL to evade conviction. Although patients recovered with supportive care, respiratory failure and cardiac arrest occurred after GHB/GBL use. It is important to legislate GBL and BD as controlled chemical substances in Taiwan.

[Acute severe oral poisoning with 1,4-butandiol and ethanol with the development of coma]

A case of acute oral poisoning by 1.4-butanediol, complicated by the development of severe hypoxia in a 34-year-old patient actively engaged in bodybuilding, is presented. The psychoactive substance was used by the patient to increase sexual activity and physical stamina. The duration of systematic daily intake was 4 months. The toxicogenic stage of acute poisoning was caused by a single dose of 50 ml of undiluted 13% 1.4-butanediol together with ethanol, manifested by convulsive syndrome, depression of consciousness to the level of coma II, acute respiratory failure with aspiration syndrome, respiratory acidosis (pH 7.22; partial pressure carbon dioxide 61.2 mm Hg), lactic acidosis up to 7 mmol / L, hyperammonemia up to 240 μmol / L, cerebral edema (decrease in white matter density to 21.6 ± 1.7 HU units), loss of vascular tone resistance (pareso arterioles) and a significant increase in cerebral blood flow rate to 115 ± 20.1 ml / 100 g per minute, increasing the volume of extracellular fluid (+ 130% of the proper volumes). Intensive therapy was complex, including infusion and detoxification therapy, correction of acid-base disorders, hypoxic disorders by using a substrate antihypoxant (Cytoflavin) in a daily dosage of 0.57 ml / kg body weight daily, for 9 days. The article discusses the toxicokinetics and toxicodynamics of 1.4-butanediol, radiation diagnostics and the clinical picture of acute poisoning, the features of its course, and pathogenetic approaches to therapy.

Gamma-hydroxybutyrate abuse: pharmacology and poisoning and withdrawal management

Gamma-hydroxybutyrate (GHB) is a central nervous system depressant primarily used as a recreational drug of abuse, but also for the treatment of narcolepsy with cataplexy in adult patients and as an adjuvant for control of alcohol withdrawal syndrome. The main aim of this review is to summarise updated knowledge about GHB pharmacokinetics and pharmacodynamics, acute poisoning, and clinical features of GHB withdrawal syndrome, its diagnosis and medical treatment. The most common clinical signs and symptoms of acute poisoning include sleepiness to deep coma, bradycardia, hypotension, and respiratory failure. Therapy is essentially supportive and based on continuous monitoring of vital signs. GHB withdrawal syndrome shares patterns with other withdrawal syndromes such as alcohol withdrawal and is sometimes difficult to distinguish, especially if toxicological tests are GHB-negative or cannot be performed. There are no official detoxification protocols for GHB withdrawal syndrome, but its therapy is based on benzodiazepine. When benzodiazepine alone is not effective, it can be combined with barbiturates or antipsychotics. Information about abuse and distribution of GHB and its precursors/analogues among the general population is still limited. Their prompt identification is therefore crucial in conventional and non-conventional biological matrices, the latter in particular, to clarify all the issues around this complex molecule.

DARK Classics in Chemical Neuroscience: Gamma-Hydroxybutyrate (GHB)

Gamma-hydroxybutyrate (GHB) is a naturally occurring short-chain fatty acid that rose to prominence as a popular club drug in the 1990s. Originally developed as an anesthetic in the early 1960s, it was later sold as an over-the-counter dietary supplement before becoming a rising substance of abuse in the following decades as one of the "date rape" drugs. Despite its abuse potential, there has been a recent surge in therapeutic interest in the drug due to its clinical viability in the treatment of narcolepsy and alcohol abuse/withdrawal. Its interactions with the GABAergic framework of higher mammals has made it the prototypical example for the study of the chief inhibitory mechanism in the human central nervous system. Though relatively obscure in terms of popular culture, it has a storied history with widespread usage in therapeutic, recreational ("Chemsex"), and some disturbingly nefarious contexts. This Review aims to capture its legacy through review of the history, synthesis, pharmacology, drug metabolism, and societal impact of this DARK classic in chemical neuroscience.

Prospective Investigation of the Performance of 2 Gamma-Hydroxybutyric Acid Tests: DrugCheck GHB Single Test and Viva-E GHB Immunoassay

BACKGROUND

Gamma-hydroxybutyric acid (GHB) is a recreational drug with central nervous system depressing effects that is often abused. A urine GHB point-of-care test can be of great diagnostic value. The objective of this prospective study was to determine the performance of the new DrugCheck GHB Single Test and the Viva-E GHB immunoassay for urine samples in emergency department patients.

METHODS

Patients presented to the emergency department of the OLVG hospital in Amsterdam with a Glasgow Coma Scale score <15 and potential drug of abuse intoxication were included in the study. Between June 2016 and October 2017, 375 patients were included. Using the DrugCheck GHB Single Test (Express Diagnostics Int'l, Blue Earth, MN) and the Viva-E GHB immunoassay (Siemens Healthineers, The Hague, the Netherlands), patients' urine samples were tested for GHB (cutoff for a positive result, 10 or 50 mcg/mL GHB). To ensure quality, the results obtained were compared with those generated using a validated gas chromatography method. The tests were considered reliable if specificity and sensitivity were both >90%. Possible cross-reactivity with ethanol was investigated by analyzing ethanol concentrations in patients' samples.

RESULTS

Seventy percentage of the included patients was men, and the median age was 34 years old. The DrugCheck GHB Single Test's specificity and sensitivity were 90.0% and 72.9%, respectively, and using 50 mcg/mL as a cutoff value, its specificity and sensitivity improved to 96.7% and 75.0%, respectively. Serum and urine ethanol levels in the false-positive group were significantly higher compared with those in the true-negative group. The specificity and sensitivity of the Viva-E GHB immunoassay (cutoff value of 50 mcg/mL and excluding samples with ethanol levels ≥2.0 g/L) were 99.4% and 93.5%, respectively.

CONCLUSIONS

The DrugCheck GHB Single Test's specificity was sufficient, whereas its sensitivity was poor, making it unsuitable for use at point-of-care. Contrarily, using 50 mcg/mL as the cutoff value and excluding samples with ethanol levels ≥2.0 g/L, the Viva-E GHB immunoassay showed acceptable results to detect clinically relevant GHB intoxications.

Hair Metabolomics in Animal Studies and Clinical Settings

Metabolomics is a powerful tool used to understand comprehensive changes in the metabolic response and to study the phenotype of an organism by instrumental analysis. It most commonly involves mass spectrometry followed by data mining and metabolite assignment. For the last few decades, hair has been used as a valuable analytical sample to investigate retrospective xenobiotic exposure as it provides a wider window of detection than other biological samples such as saliva, plasma, and urine. Hair contains functional metabolomes such as amino acids and lipids. Moreover, segmental analysis of hair based on its growth rate can provide information on metabolic changes over time. Therefore, it has great potential as a metabolomics sample to monitor chronic diseases, including drug addiction or abnormal conditions. In the current review, the latest applications of hair metabolomics in animal studies and clinical settings are highlighted. For this purpose, we review and discuss the characteristics of hair as a metabolomics sample, the analytical techniques employed in hair metabolomics and the consequence of hair metabolome alterations in recent studies. Through this, the value of hair as an alternative biological sample in metabolomics is highlighted.