Gamma-hydroxybutyrate In Blood Research Articles

In Vitro Production of Gamma-Hydroxybutyrate in Antemortem Blood Under Various Storage Conditions.

Gamma-hydroxybutyrate (GHB) is an endogenous compound and central nervous system depressant drug used recreationally for its intoxicating effects. In a medico-legal context, the interpretation of blood GHB concentrations can be complicated by its endogenous nature and potential for formation during storage. In Canada, the per se limit for GHB in blood is 5 mg/L. Endogenous GHB concentrations in blood are typically well below 5 mg/L; however, there is a paucity of literature regarding the potential production of GHB in antemortem blood during storage. Changes in GHB concentrations were evaluated over the course of 306 days in preserved and unpreserved antemortem blood stored at 4°C and 21°C. Results were compared to 22 impaired driving cases in Ontario between 2019-2022 where GHB was detected in antemortem blood by toxicological analysis at the Centre of Forensic Sciences. Preservative was effective at minimizing GHB production (< 2.5 mg/L) regardless of storage temperature whereas significant in vitro production of GHB occurred in unpreserved antemortem blood. GHB production occurred rapidly in unpreserved blood stored at 21°C; a significant increase was detected after 5 days. The rate of GHB production in unpreserved blood stored at 4°C occurred more gradually but increased significantly by day 30 and reached a maximum concentration of 10 mg/L at 114 days. In unpreserved blood, GHB concentrations were significantly lower at 4°C compared to 21°C for the first 44 days; however, refrigeration had no significant effect then onward. Blood concentrations of GHB detected in the majority of impaired driving cases were markedly higher than the maximum concentration of 10 mg/L detected in the study; however, in 4 of the 22 cases, concentrations were below 10 mg/L. The results demonstrate that concentrations of GHB less than 10 mg/L in blood collected for the purposes of a drug impaired driving investigation should be carefully interpreted.

Effect of body refrigeration on the postmortem formation of gamma hydroxybutyrate in whole blood

Gamma hydroxybutyrate (GHB) levels in biological fluids are known to be increased after death. To date, there have been studies on sample storage conditions and preservatives on the postmortem in vitro formation of GHB. However, only few studies explored the effects of body storage conditions on GHB formation after death. In this study, we determined the effect of body refrigeration during body storage in mortuary refrigerators on postmortem formation of GHB in whole blood samples. A total of 41 fatalities were divided into two groups: Group A with a total refrigeration time less than 10 h and Group B with a total body refrigeration time more than 10 h. Femoral blood was collected 3 times: upon arrival at the mortuary, after 4 h of refrigeration, and at autopsy. Rectal temperatures were recorded at the time of specimen collection. Blood GHB concentration was analyzed by LC-MS/MS. The rate of change in GHB levels was calculated. The study revealed that in the later phase of refrigeration, no difference was observed in the blood GHB levels between the two groups despite differences in the postmortem interval (PMI) and refrigeration time. Moreover, the rate of change in the GHB levels was lower in the group with a longer refrigeration time. Hence, we concluded that once the plateau of postmortem GHB formation is reached in a refrigerated body, further formation is not expected even with prolonged PMI. Early body refrigeration can minimize postmortem GHB production, thereby preventing the incorrect interpretation of analytical results.

Application of dispersive liquid-liquid microextraction and GC–MS/MS for the determination of GHB in beverages and hair

Recently, gamma-hydroxybutyrate (GHB) was determined in “Kawa Trendy Drink” which was labeled as a functional beverage containing gamma-aminobutyric acid and quickly became popular in various club in China. GHB has a strong sedative effect and is often used as a date rape drug and euphoriant in drug-facilitated sexual assaults. However, it is believed that same beverages themselves contain natural GHB. Whether GHB contained in seized beverages was added or exists in themselves resulted in complicated interpretation of the nature of cases. The detection window of GHB in blood (5 h) and urine (<12 h) was narrow, make documentation of GHB exposure difficult, while hair can extend the detection time of GHB from several hours to several days/months. Thus, a sensitive detection method based on dispersive liquid-liquid microextraction (DLLME) and GC–MS/MS for GHB in beverages and hair had been established. Under the optimum extraction conditions, acceptable linear relationship was achieved in the range of 1.5–500 ng/mL with the correlation coefficient (r) of 0.9986 for spiked water samples and in the range of 0.03–10 ng/mg with the correlation coefficient (r) of 0.9979 for spiked melanin samples. The LOD (S/N = 3) was estimated to be 0.5 ng/mL and 0.01 ng/mg, respectively. A recovery of 70.6–88.5% were obtained for spiked samples. The mean relative error (MRE) was within ±6.5% and the relative standard error (RSD) was less than 4.9%. The combination of DLLME with GC–MS/MS offers an alternative analytical approach for the sensitive detection of GHB in real beverages sold in Chinese markets and in hair of Chinese population for forensic purposes. The proposed methods had the advantages of shorter extraction time and were suitable for simultaneous pretreatment of samples in batches. To our knowledge, this is the first report to present GHB in beverages and human hair using DLLME.

Detection of gamma hydroxybutyrate in emergency department: Nice to have or a valuable diagnostic tool?

Many patients present to emergency departments (EDs) with an altered state of consciousness. Fast exclusion of gamma hydroxybutyrate (GHB)-associated intoxication in these patients may optimize diagnostic and therapeutic algorithms and decisions in the ED. Between January and March 2014, a novel enzymatic test system was used to quantify GHB in blood and urine samples of suspected intoxicated patients in the ED of the University Hospital. The underlying causes for suspected intoxication and the diagnostic and therapeutic measures were documented and analysed retrospectively. GHB measurements were performed in 13 patients with suspected ingestion during a 3-month study period. GHB was positive in six patients showing serum levels between 61.8 mg/l and 254.8 mg/l, and GHB was tested negative in seven patients with a range of 0.3-6.2 mg/l (upper reference limit 6.1 mg/l). Additional intoxication was found in five of six GHB positive (83%, alcohol n = 2 and other drugs n = 5) and in six of seven negative-tested patients (86%, alcohol n = 5 and other drugs n = 1). GHB quantification in the ED provides specific additional information for intoxication, which can lead to more precise diagnostic and therapeutic decisions and may also be important for legal aspects. We believe that GHB analysis in unconscious patients with suspected intoxication may improve the efficient treatment of intoxicated patients.

Endogenous concentrations of GHB in postmortem blood from deaths unrelated to GHB use.

Gamma-hydroxybutyrate (GHB) is an endogenous compound, but its presence in postmortem blood presents a challenge when interpreting elevated levels as GHB is misused as a recreational drug and is also produced postmortem. A total of 387 postmortem cases (273 male and 114 female) submitted to the toxicology laboratory between 2010 and 2012 specifically requested the analysis of the ketoacidosis biomarker, beta-hydroxybutyrate (BHB). No reference to GHB use was identified in any of the case files; however, BHB and GHB are measured simultaneously using deuterated GHB as the internal standard (GHB-d6) within a calibration range of 5-500 mg/L. GHB was not detected or <10 mg/L in 18% of the cases (n = 68), between 10 and 50 mg/L in 73% of the cases (n = 283) and between 51 and 193 mg/L in 9% of the cases (n = 36). The manner of death was classified as accidental (n = 11), alcohol-related (n = 237), drug-related (n = 23), homicide (n = 1), natural (n = 91), suicide (n = 9), medical-related (n = 1) and undetermined (n = 14). Six cases had GHB concentrations in excess of 100 mg/L with advanced decomposition changes noted in five of these cases. Moderate-to-advanced decomposition was also noted in 50% (n = 15) of the cases with GHB concentrations in excess of 50 mg/L but <100 mg/L. Approximately one-third of the blood samples tested contained a preservative and although a higher proportion of these samples had GHB concentrations <10 mg/L or not detected (∼30% preserved versus 11% unpreserved), there were still cases with GHB concentrations >51 mg/L (∼6% preserved versus 11% unpreserved). This study highlights the danger of only using a cutoff to establish endogenous levels compared with exogenous use of GHB in postmortem blood.

Post mortem concentrations of endogenous gamma hydroxybutyric acid (GHB) and in vitro formation in stored blood and urine samples

Gamma-hydroxybutyrate (GHB) is a central nervous system depressant, primarily used as a recreational drug of abuse with numerous names. It has also been involved in various instances of drug-facilitated sexual assault due to its potential incapacitating effects.The first aim of this paper is to measure the post-mortem concentration of endogenous GHB in whole blood and urine samples of 30 GHB free-users, who have been divided according to the post-mortem interval (PMI) in three groups (first group: 24–36h; second group: 37–72h; third group: 73–192h), trying to evaluate the role of PMI in affecting post mortem levels. Second, the Authors have evaluated the new formation of GHB in vitro in blood and urine samples of the three groups, which have been stored at −20°C, 4°C and 20°C over a period of one month.The concentrations were measured by GC–MS after liquid–liquid extraction according to the method validated and published by Elliot (For. Sci. Int., 2003). For urine samples, GHB concentrations were creatinine-normalized.In the first group the GHB mean concentration measured after autopsy was: 2.14mg/L (range 0.54–3.21mg/L) in blood and 3.90mg/g (range 0.60–4.81mg/g) in urine; in the second group it was: 5.13mg/L (range 1.11–9.60mg/L) in blood and 3.93mg/g (range 0.91–7.25mg/g) in urine; in the third group it was: 11.8mg/L (range 3.95–24.12mg/L) in blood and 9.83mg/g (range 3.67–21.90mg/g) in urine.The results obtained in blood and urine samples showed a statistically significant difference among groups (p<0.001) in the first analysis performed immediately after autopsy.Throughout the period of investigation up to 4 weeks, the comparison of storage temperatures within each group showed in blood and urine samples a mean difference at 20°C compared to −20°C not statistically significant at the 10% level.These findings allow us to affirm that the PMI strongly affects the post mortem production of GHB in blood and urine samples. Regarding the new formation of GHB in vitro both in blood and urine samples of the three groups, which have been stored at −20°C, 4°C and 20°C over a period of one month, although there was no significant increases of GHB levels throughout the period of investigation, the lowest increases were found both in blood and urine at −20°C, therefore we recommend the latter as optimal storage temperature.

Determination of gamma-hydroxybutyrate (GHB), beta-hydroxybutyrate (BHB), pregabalin, 1,4-butane-diol (1,4BD) and gamma-butyrolactone (GBL) in whole blood and urine samples by UPLC–MSMS

The demand of high throughput methods for the determination of gamma-hydroxybutyrate (GHB) and its precursors gamma-butyrolactone (GBL) and 1,4-butane-diol (1,4BD) as well as for pregabalin is increasing. Here we present two analytical methods using ultra-high pressure liquid chromatography (UPLC) and tandem mass spectrometric (MS/MS) detection for the determination of GHB, beta-hydroxybutyrate (BHB), pregabalin, 1,4BD and GBL in whole blood and urine. Using the 96-well formate, the whole blood method is a simple high-throughput method suitable for screening of large sample amounts. With an easy sample preparation for urine including only dilution and filtration of the sample, the method is suitable for fast screening of urine samples. Both methods showed acceptable linearity, acceptable limits of detection, and limits of quantification. The within-day and between-day precisions of all analytes were lower than 10% RSD. The analytes were extracted from matrices with recoveries near 100%, and no major matrix effects were observed. Both methods have been used as routine screening analyses of whole blood and urine samples since January 2010.

Blood GHB concentrations and results of medical examinations in 25 car drivers in Norway

information on the clinical effects associated with whole blood gamma-hydroxybutyrate (GHB) concentrations is sparse. We have investigated possible relationships between GHB blood concentrations and clinical effects in car drivers. in Norway, the police stop car drivers suspected of drug-driving. Medical doctors perform a clinical test of impairment (CTI) and blood samples are screened for drugs/medicines by immunological, enzymatic and chromatographic methods at the Division of Forensic Toxicology and Drug Abuse. GHB is a part of our extended drug-testing programme. GHB is standardly measured as GBL by gas chromatographic method. All the results were stored in a database. This database was searched between 2000 and 2007 for car drivers positive only for GHB, called GHB-drivers. A control group with a completely negative blood analysis, including GHB, called control-drivers, was included in the study. twenty-five car drivers had only GHB in their blood. The police reported that 78% showed unsafe driving behaviour and seven were involved in car accidents, without serious injury. A total of 61% of the drivers were found to be sleepy or in an even more reduced state of consciousness. The median GHB blood concentration was 1,262 (range 592-2,191) μmol/L, measured a median of 69 min after the police had stopped the driver from driving. The GHB blood concentration tended to increase with increasing impairment and reduced consciousness. Clinical findings were normal- to large-sized pupils (86%), impairment as the final conclusion (84%), impaired balance/nystagmus (62 and 54%, respectively), congested/shiny conjunctiva (67%), apathetic, aggressive or abnormal behaviour (65%), reduced short-term memory (67%), reduced/absent pupillar reaction to light (65%), heart rate ≤ 70 beats/min (56%), and some level of reduced consciousness (56%). In the control-drivers, 15.6% were found by the medical doctors to have reduced consciousness or impaired. the median GHB blood concentration of the 25 car drivers was high. Most drivers had clinical impairment that was not explainable by injuries, with depressive effects on the central nervous system and sympathomimetic effects on eyes. Effects on impairment and consciousness tended to be concentration-dependent. The number of drivers who were impaired or had reduced consciousness was highly increased in GHB-drivers compared to controls. Based on these results, we conclude that the GHB-drivers most probably drove in an unsafe manner due to impairment by GHB.

Concentration-Time Profiles of Gamma-Hydroxybutyrate in Blood After Recreational Doses are Best Described by Zero-Order Rather Than First-Order Kinetics

The recreational drug gamma-hydroxybutyrate (GHB) has a short plasma elimination half-life (t(1/2)) reported to be about 30-50 min. However, this represents a terminal half-life and therefore might not necessarily apply after large (abuse) doses are taken. Clinical studies with sodium oxybate (sodium salt of GHB) suggest that zero-order rather than first-order kinetics are more appropriate to describe post-peak concentration-time (C-T) profiles. We report the case of a 23-year-old male found unconscious by the police and a blood sample contained 100 mg/L GHB and 0.14 g% ethanol. On regaining consciousness the man admitted drinking alcohol about 6 h earlier but claimed that his drink must have been spiked with GHB. The police wanted to know how much GHB had been administered to account for the man's clinical condition. A back-calculation for 6 h, assuming a GHB half-life of 40 min, gives a very high concentration in blood of approximately 900 mg/L, which would probably have proven fatal. Back-calculating using zero-order kinetics and a proposed elimination rate of 18 mg/L per hour leads to a GHB concentration of 208 mg/L, which is much more realistic. Toxicologists should not arbitrarily apply the principles of first-order kinetics after abuse doses of drugs, when zero-order or saturation kinetics (Michaelis-Menten) are more appropriate.

Three deaths associated with use of Xyrem ®

Fatalities resulting from popular use of gamma hydroxybutyrate (GHB) have previously been reported. We report three deaths associated with use of Xyrem ® (sodium oxybate), a pharmaceutical preparation of GHB initially approved for treatment of narcolepsy with cataplexy. One death appears associated with Xyrem ® abuse, with extremely high postmortem blood GHB levels documented. Although postmortem blood GHB levels in two other deaths are consistent with therapeutic levels, cause and effect cannot be established. We discuss these cases and factors which may have exerted contributory respiratory depressant effects, singly or in combination, including concurrent use of sedative hypnotics, obstructive sleep apnea, and obesity.

A Multi‐Drug Intoxication Fatality Involving Xyrem® (GHB)

Gamma-hydroxybutyrate (GHB) is best known as a recreational depressant drug, whose use has also been implicated in drug facilitated sexual assault cases. It is also available as a therapeutic agent (Xyrem) used for the treatment of daytime sleepiness or cataplexy associated with narcolepsy. This is a report of a case of a 53-year-old woman undergoing treatment with Xyrem for narcolepsy. The decedent was also prescribed tramadol, gabapentin, cetirizine, modafinil, carisoprodol, and Xyrem. Toxicological analysis of the blood revealed GHB 165.6 mg/L, and 90.7 mg/L in the urine. Blood GHB concentrations in the range 156-260 mg/L have been reported to induce moderately sound sleep. The combined use of central nervous system depressant drugs, together with her problematic sleep apnea, and snoring (both contraindications for GHB use) were determined to have caused this subject's death. The manner of death was determined to be accidental.

Forensic toxicology findings in deaths involving gamma-hydroxybutyrate

Concentrations of the illicit drug gamma-hydroxybutyrate (GHB) were determined in femoral venous blood and urine obtained at autopsy in a series of GHB-related deaths (N = 49). The analysis of GHB was done by gas chromatography after conversion to gamma-butyrolactone and quantitation of the latter with a flame ionization detector. The cutoff concentration of GHB in femoral blood or urine for reporting positive results was 30 mg/L. The deceased were mainly young men (86%) aged 26.5 +/- 7.2 years (mean +/- SD), and the women (14%) were about 5 years younger at 21.4 +/- 5.0 years. The mean, median, and highest concentrations of GHB in femoral blood (N = 37) were 294, 190, and 2,200 mg/L, respectively. The mean urine-to-blood ratio of GHB was 8.8, and the median was 5.2 (N = 28). In 12 cases, the concentrations of GHB in blood were negative (<30 mg/L) when the urine contained 350 mg/L on average (range 31-1,100 mg/L). Considerable poly-drug use was evident in these GHB-related deaths: ethanol (18 cases), amphetamine (12 cases), and various prescription medications (benzodizepines, opiates, and antidepressants) in other cases. Interpreting the concentrations of GHB in postmortem blood is complicated because of concomitant use of other psychoactive substances, variable degree of tolerance to centrally acting drugs, and the lack of reliable information about survival time after use of the drug.

Driving under the influence of gamma-hydroxybutyrate (GHB)

We used an in-house forensic toxicology database (TOXBASE) to evaluate the occurrences of gamma-hydroxybutyrate (GHB) in blood samples from people arrested in Sweden for driving under the influence of drugs (DUID) between 1998 and 2007. Age, gender, and concentrations of GHB in blood were compared and contrasted when GHB was the only drug present and when it occurred along with other drugs. GHB was determined in blood by gas chromatography (GC) after conversion to gamma-butyrolactone (GBL) and analysis of the latter with a flame ionization detector. The cut-off concentration of GHB in blood for reporting a positive result was 8 mg/l, which served as limit of quantitation. The mean and median GHB concentrations were 89 mg/l and 82 mg/l, respectively (2(1/2) and 97(1/2) percentiles 12 and 220 mg/l) in 548 arrested drivers. These individuals were predominantly men (95%) with an average age of 26 +/- 5.5 years (range 15-50 years) and women (5%) were several years older with an average age of 32 +/- 8.0 years (range 19-47). There were 102 individuals (29%) who were arrested more than once with GHB in blood (average approximately 3 times per person) and one as many as 10 times. GHB was the only psychoactive substance detected in 215 cases (39%) at mean and median blood-concentrations of 91 mg/l and 83 mg/l, respectively. These concentrations were not significantly different from poly-drug users. A weak but statistically significant correlation existed between the concentration of GHB in blood and the person's age (N = 548, r = 0.135, P < 0.01). The signs of drug influence noted by arresting police officers included sedation, agitation, unsteady gait, slurred speech, irrational behavior, jerky body movements, dilated pupils, and spitting. The blood concentrations reported here are probably appreciably less than at time of driving (30-90 min earlier) owing to the short elimination half-life of GHB (t ((1/2)) = 30-40 min).

Gamma-Hydroxybutyrate Concentrations in the Blood of Impaired Drivers, Users of Illicit Drugs, and Medical Examiner Cases

Gamma-hydroxybutyrate (GHB) was determined in blood samples from impaired drivers, people arrested for petty drug offenses (non-traffic cases), and GHB-related deaths. The method of analysis involved conversion of GHB into gamma-butyrolactone and determination of the latter by gas chromatography with a flame ionization detector, and with gamma-valerolactone as the internal standard. The mean and median concentrations of GHB in blood from impaired drivers (N=473) were 90 and 84 mg/L, respectively, and offenders were predominantly men (96%) with an average age of 26 year (range 15-50 year). In 185 cases, GHB was the only drug present in blood at mean and median concentrations of 92 and 86 mg/L, respectively. People arrested for petty drug offenses (N=1061) had slightly higher GHB concentrations in their blood: median 118 mg/L for men and 111 mg/L for women. In GHB-related deaths (N=33), the mean and median concentrations were considerably higher: 307 mg/L and 190 mg/L, respectively, and the highest was 2200 mg/L. The typical signs of drug influence noted by the arresting police officers included sedation, agitation, slurred speech, irrational behaviour, jerky movements, and spitting. The short elimination half-life of GHB means that the concentrations in blood decrease rapidly and are probably a lot lower than at the time of driving, which was 30-90 min earlier.

Potential Surrogate Markers for Gamma-Hydroxybutyrate Administration May Extend the Detection Window from 12 to 48 Hours

The exogenous administration of gamma-hydroxybutyrate (GHB) as a drug of abuse, and especially in date rape sexual assaults, has recently increased. Chromatographic techniques are used to detect GHB in blood or urine, with a window of detection limited to 12 h. This brief window makes the proof of administration problematic in most rape cases. This study is aimed to extend the window of detection through surrogate markers of GHB administration. Microarray technology is used in a DBA/2J mouse model to detect gene expression changes in peripheral blood after GHB exposure at times as long as 96 h post exposure. This study focuses on two of the most significantly altered transcripts, epiregulin and phosphoprotein enriched in astrocytes 15 (Pea-15). Both genes have increased the ribonucleic acid expression (8.5- and 4.6-fold upregulation at 96 h, respectively) in GHB-dosed mice (1 g/kg) as compared with the control. To confirm these results at the protein level, an intracellular flow cytometric assay is developed to detect protein level changes in the peripheral blood of both these potential biomarkers after GHB exposure. These results suggest that after further development, epiregulin and Pea-15 may prove to be significant surrogate markers in the indirect detection of GHB administration.

Chronic intragastric administration of gamma-butyrolactone produces physical dependence in baboons

Abuse of gamma-hydroxybutyrate (GHB) and its precursors is a public health concern. Gamma-butyrolactone (GBL) is found in commercially available products and, when ingested, is metabolized to GHB. The goal was to evaluate the physical dependence potential and behavioral effects of GBL. Vehicle and then GBL were administered continuously (24 h per da y) in baboons (Papio anubis, n=5) via intragastric catheters. GBL dosing was initiated at 100 mg/kg/day and then progressively increased stepwise by increments of 100 mg/kg to a final dose of 600 mg/kg. The number of food pellets earned, fine-motor task performance, and observed behaviors were used as dependent measures. Precipitated withdrawal was evaluated after administration of GABA-B and benzodiazepine receptor antagonists during chronic GBL dosing (400-600 mg/kg). Spontaneous withdrawal was evaluated after discontinuation of chronic GBL 600 mg/kg. Blood GHB levels were determined during chronic dosing of each GBL dose by isotope dilution assay. Chronic GBL dose-dependently decreased food-maintained behavior, disrupted performance on the fine-motor task, and produced signs of sedation and muscle relaxation. The GABA-B antagonist SGS742 [56 mg/kg, intramuscular (IM)] precipitated a withdrawal syndrome, whereas the benzodiazepine antagonist flumazenil (5 mg/kg, IM) produced little or no effect. Signs of physical dependence were also demonstrated when chronic GBL dosing was discontinued. Analysis of plasma indicated GBL was metabolized to GHB; levels were 825 to 1,690 micromol l(-1) GHB and 2,430 to 3,785 micromol l(-1) GHB after week 1 of 400 and 600 mg/kg/day, respectively. These data indicate that, like GHB, chronic GBL dosing produced physical dependence that likely involved the GABA-B receptor.

GC-MS-MS Determination of Gamma-Hydroxybutyrate in Blood and Urine

A gas chromatographic-tandem mass spectrometric (GC-MS-MS) method for determining trace concentrations of gamma-hydroxybutyrate (GHB) in blood and urine has been developed. Multiple reaction monitoring was used to detect parent and daughter ions of GHB, 233 and 147, respectively, following liquid-liquid extraction with acetonitrile and derivatisation with N,O-bis[trimethylsilyl]trifluoroacetamide (BSTFA). Deuterated GHB was used as an internal standard. The assay produced excellent linearity and sensitivity without conversion to gamma butyrolactone. The lower limit of quantitation (LLOQ) in 50 microL of sample was 2.5 microg/mL. The expanded uncertainty values for intra- and interassay results were +/- 0.097 and +/- 0.123 ng/mL at a confidence level of 95% for blood and urine, respectively. Endogenous concentrations of GHB were found to be in the range of 0.3 to 6 microg/mL in urine and 0.5 to 2.3 microg/mL in blood, confirming previously suggested cut-off values for forensic analysis.

Gamma-hydroxybutyrate – a drug of abuse

Gamma-hydroxybutyrate (GHB) is a drug of abuse that causes euphoria, anxiolysis, and hypnosis. The recent rise in the recreational intake of GHB, as well as its association with 'drug rape', has turned the attention to GHB in acute hospital settings. Acutely admitted GHB intoxicated patients may display various levels of sedation or coma, but may also show paradoxical agitation, combativeness, or self-injurious behaviors. The symptoms can be nonspecific and the definite diagnosis therefore normally relies on the detection of GHB in blood or body fluids, which is an analysis that may not be promptly available. As a basis for understanding the clinical features of GHB intoxication and abuse, we here review the pharmacological and neurophysiological knowledge about GHB, which stems from decades of clinical and basic GHB research. In addition, we discuss the latest discoveries in the quest for distinct GHB receptors in the brain, and their possible implications for future therapies of GHB abuse.

Detection of Exogenous GHB in Blood by Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometry: Implications in Postmortem Toxicology

Because GHB (gamma-hydroxybutyrate) is present in both blood and urine of the general population, toxicologists must be able to discriminate between endogenous levels and a concentration resulting from exposure. In this paper, we propose a procedure for the detection of exogenous GHB in blood by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Following liquid-liquid and solid-phase extractions, GHB is derivatized to GHB di-TMS before analysis by GC-C-IRMS. Significant differences in the carbon isotopic ratio (delta(13)C-values > 13.5 per thousand) were found between endogenous and synthetic GHB. Indeed, for postmortem blood samples with different GHB concentrations (range: 13.8-86.3 mg/L), we have obtained GHB delta(13)C-values ranging from -20.6 to -24.7 per thousand, whereas delta(13)C-values for the GHB from police seizure were in the range -38.2 to -50.2 per thousand. In contrast to the use of cut-off concentrations for positive postmortem blood GHB concentrations, this method should provide an unambiguous indication of the drug origin.

Distribution of GHB in Tissues and Fluids Following a Fatal Overdose

Gamma-hydroxybutyrate (GHB) is encountered in biological specimens as an endogenous neuromodulator, recreational drug, or therapeutic agent. Clinically, the drug is useful for the treatment of cataplexy. Illicit doses are typically 2-4 g, and the onset of action is rapid, occurring 15-30 min following oral ingestion. Dose-dependent effects include drowsiness, euphoria, dizziness, vomiting, respiratory depression, coma, and death. GHB was isolated from biological samples using a simple liquid-liquid extraction. The trimethylsilyl derivative (GHB-di-TMS) was analyzed using gas chromatography-mass spectrometry with positive chemical ionization. Deuterated internal standard and selective ion monitoring were used throughout. We report a GHB fatality involving a 35-year-old male who was partying with friends. Subjects at the party ingested unknown quantities of wine and GHB. A female companion at the party reported seeing the male alive before she herself passed out. She awoke to find the decedent cold and stiff. Postmortem specimens were submitted for comprehensive toxicology testing. No alcohol or common drugs of abuse were detected. A targeted analysis revealed GHB in urine, brain, vitreous fluid, femoral blood, heart blood, and liver at concentrations of 1665 mg/L, 102 mg/kg, 48 mg/L, 461 mg/L, 276 mg/L, and 52 mg/kg, respectively. Concentrations of the drug in urine and vitreous fluid are important in death investigations because of significant postmortem production of GHB in blood specimens. The cause of death was attributed to GHB intoxication, and the manner of death was accidental.