Forensic toxicology findings in deaths involving gamma-hydroxybutyrate

Changes in the rates and characteristics of gamma hydroxybutyrate (GHB)-related death in Australia, 2001-2023

INTRODUCTION

In recent years gamma hydroxybutyrate (GHB) use appears to have increased. This study aimed to determine: (i) population rates of GHB-related death in Australia, 2001-2021; and (ii) whether there have been changes in the characteristics of GHB-related death in Australia over the period 2001-2023.

METHODS

Retrospective study of all Australian cases in which GHB was a mechanism contributory to death retrieved from the National Coronial Information System (n = 217). Joinpoint regression models were used to analyse trends in overall rates.

RESULTS

Death rates were stable between 2001 and 2015 ('stable period') (annual percent change [APC] = 3.7) but showed marked acceleration between 2016 and 2021 ('accelerated period') (APC = 44.4). Circumstances of death were: unintentional toxicity (81.6%), intentional toxicity (5.1%), self-harm (6.0%), traumatic injury (7.4%). Compared to the stable period, later cases were slightly older (34.2 vs. 30.7 years, p < 0.05), less likely to be employed (odds ratio [OR] 0.4), but more likely to have substance use problems (OR 3.9), a history of injecting drug use (OR 3.5), mental health problems (OR 3.6), and to have present in their blood at toxicological screening opioids (OR 3.2) and hypnosedatives (OR 3.7). The median blood GHB concentration was 170 mg/L, (range 0-3210), which did not change significantly. There were no differences in major organ pathology, but the proportion with aspiration pneumonia declined (OR 0.4).

DISCUSSION AND CONCLUSIONS

GHB-related death rates increased from 2016, accompanied by changes in case characteristics. In recent years GHB use appears to have extended to a population more likely to have substance use problems and use other respiratory depressants.

Drug-related deaths at Australian music festivals

BACKGROUND

Illicit drug use is overrepresented in music festival attendees compared with the general population. Drug use often involves a wide range of substances with the potential to cause drug toxicity. Law enforcement-centred strategies intended to deter drug use and supply at these mass gatherings have been implemented throughout Australia. However, many have been criticised for their lack of effectiveness, with evidence suggesting that they can inadvertently increase the risk of drug harm. Drug deaths are often multifactorial, providing added challenges in the development of prevention strategies. This study aimed to determine the frequency of deaths involving alcohol and other drugs at music festivals in Australia and to identify potential risk factors that may inform future harm reduction strategies.

METHODS

A descriptive case series study was conducted using the National Coronial Information System (NCIS) to investigate drug-related deaths at music festivals throughout Australia between 1 July 2000 (Queensland from 1 January 2001) and 31 December 2019, using a list of keywords comprising music festival names and terms.

RESULTS

There were 64 deaths, of which most involved males (73.4%) aged in their mid-20s (range 15-50 years). Drug toxicity was the most common primary cause of death (46.9%) followed by external injuries (37.5%). The drug most commonly detected or reported as being used was MDMA (65.6%), followed by alcohol (46.9%) and cannabis (17.2%), with most cases reporting the use of two or more drugs (including alcohol) and 36% reporting a history of drug misuse in the coroner's findings. Most deaths were unintentional, with less than a fifth of cases (17.2%) involving intentional self-harm. Clinical intervention was involved in 64.1% of cases and most festivals occurred in inner city locations (59.4%).

CONCLUSIONS

The findings suggest that drug-related deaths at music festivals in Australia typically involve young people using multiple illicit substances in combination with alcohol. Most are unintentional and could potentially be prevented through the implementation of a range of harm reduction strategies, including mobile medical care, drug checking services, and increased consumer education and awareness.

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.

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.

Metabolic Alterations Associated with γ-Hydroxybutyric Acid and the Potential of Metabolites as Biomarkers of Its Exposure

γ-Hydroxybutyric acid (GHB) is an endogenous short chain fatty acid that acts as a neurotransmitter and neuromodulator in the mammalian brain. It has often been illegally abused or misused due to its strong anesthetic effect, particularly in drug-facilitated crimes worldwide. However, proving its ingestion is not straightforward because of the difficulty in distinguishing between endogenous and exogenous GHB, as well as its rapid metabolism. Metabolomics and metabolism studies have recently been used to identify potential biomarkers of GHB exposure. This mini-review provides an overview of GHB-associated metabolic alterations and explores the potential of metabolites for application as biomarkers of GHB exposure. For this, we discuss the biosynthesis and metabolism of GHB, analytical issues of GHB in biological samples, alterations in metabolic pathways, and changes in the levels of GHB conjugates in biological samples from animal and human studies. Metabolic alterations in organic acids, amino acids, and polyamines in urine enable discrimination between GHB-ingested animals or humans and controls. The potential of GHB conjugates has been investigated in a variety of clinical settings. Despite the recent growth in the application of metabolomics and metabolism studies associated with GHB exposure, it remains challenging to distinguish between endogenous and exogenous GHB. This review highlights the significance of further metabolomics and metabolism studies for the discovery of practical peripheral biomarkers of GHB exposure.

Characteristics and circumstances of death related to gamma hydroxybutyrate (GHB)

Introduction: Gamma hydroxybutyrate (GHB) has gained substantial popularity as an illicit recreational drug. The current study aimed to: (1) determine the characteristics and circumstances of death of all recorded cases of GHB-related death in Australia, 2001-2019; (2) determine the toxicology of cases; and (3) determine major organ pathology.Methods: Retrospective study of all Australian cases in which GHB was a mechanism contributory to death retrieved from the National Coronial Information System (n = 74). Information was collected on cause of death, demographics, circumstances of death, toxicology and major organ pathology.Results: The mean age was 31.5 years and 70.3% were male. The predominant circumstance of death was accidental drug toxicity (79.7%), including five cases attributed to a combination of toxicity and natural disease. Other deaths were due to trauma (12.2%) and suicide (8.2%). The fatal incident overwhelmingly occurred in a home environment (82.4%). In all cases, GHB was consumed orally. The median GHB blood concentration was 210 mg/L (range 13-1350 mg/L), and was significantly higher in toxicity cases than others (258 vs. 98 mg/L, p < .01). Other substances were present in 92.2%, most commonly psychostimulants (64.1%), hypnosedatives (28.2%) and alcohol (20.3%). Resuscitation was attempted in 20.3% of cases. Acute pneumonia (36.7%) and aspiration of vomitus (30.6%) were common.Conclusions: The typical case was a young male, who swallowed GHB and used it with other substances, most commonly at home. While acute drug toxicity was the most common cause of death, there was a substantial minority due to trauma or suicide.

The challenge of post-mortem GHB analysis: storage conditions and specimen types are both important

BACKGROUND

For the interpretation of concentrations of gamma-hydroxybutyrate (GHB) in post-mortem specimens, a possible increase due to post-mortem generation in the body and in vitro has to be considered. The influence of different storage conditions and the specimen type was investigated.

METHOD AND MATERIAL

Post-mortem GHB concentrations in femoral venous blood (VB), heart blood (HB), serum (S) from VB, urine (U), cerebrospinal fluid (CSF) and vitreous humour (VH) were determined by gas chromatography-mass spectrometry after derivatisation. Various storage conditions, that is 4 °C or room temperature (RT) and the addition of sodium fluoride (NaF), were compared during storage up to 30 days. Additionally, bacterial colonisation was determined by mass spectrometry fingerprinting.

RESULTS

Twenty-six cases without involvement of exogenous GHB were examined. GHB concentrations (by specimen) at day 0 were 3.9-22.1 mg/L (VB), 6.6-33.3 mg/L (HB), < 0.5-18.1 mg/L (U), 1.1-10.4 mg/L (CSF) and 1.7-22.0 mg/L (VH). At 4 °C, concentrations increased at day 30 to 5.6-74.5 mg/L (VB), 4.6-76.5 mg/L (HB) and < 0.5-21.3 mg/L (U). At RT, concentrations rose to < 0.5-38.5 mg/L (VB), 1.2-94.6 mg/L (HB) and < 0.5-37.5 mg/L (U) at day 30. In CSF, at RT, an increase up to < 0.5-21.2 mg/L was measured, and at 4 °C, a decrease occurred (< 0.5-6.5 mg/L). GHB concentrations in VH remained stable at both temperatures (1.2-20.9 mg/L and < 0.5-26.2 mg/L). The increase of GHB in HB samples with NaF was significantly lower than that without preservation. No correlation was found between the bacterial colonisation and extent of GHB concentration changes.

CONCLUSION

GHB concentrations can significantly increase in post-mortem HB, VB and U samples, depending on storage time, temperature and inter-individual differences. Results in CSF, VH, S and/or specimens with NaF are less affected.

Interpreting γ-hydroxybutyrate concentrations for clinical and forensic purposes

INTRODUCTION

γ-Hydroxybutyric acid is an endogenous substance, a therapeutic agent, and a recreational drug of abuse. This psychoactive substance acts as a depressant of the central nervous system and is commonly encountered in clinical and forensic practice, including impaired drivers, poisoned patients, and drug-related intoxication deaths.

OBJECTIVE

The aim of this review is to assist clinical and forensic practitioners with the interpretation of γ-hydroxybutyric acid concentrations in blood, urine, and alternative biological specimens from living and deceased persons.

METHODS

The information sources used to prepare this review were PubMed, Scopus, and Web-of-Science. These databases were searched using keywords γ-hydroxybutyrate (GHB), blood, urine, alternative specimens, non-conventional biological matrices, saliva, oral fluid, sweat, hair, vitreous humor (VH), brain, cerebrospinal fluid (CSF), dried blood spots (DBS), breast milk, and various combinations thereof. The resulting 4228 references were screened to exclude duplicates, which left 1980 articles for further consideration. These publications were carefully evaluated by taking into account the main aims of the review and 143 scientific papers were considered relevant. Analytical methods: The analytical methods used to determine γ-hydroxybutyric acid in blood and other biological specimens make use of gas- or liquid-chromatography coupled to mass spectrometry. These hyphenated techniques are accurate, precise, and specific for their intended purposes and the lower limit of quantitation in blood and other specimens is 0.5 mg/L or less. Human pharmacokinetics: GHB is rapidly absorbed from the gut and distributes into the total body water compartment. Only a small fraction of the dose (1-2%) is excreted unchanged in the urine. The plasma elimination half-life of γ-hydroxybutyric acid is short, being only about 0.5-0.9 h, which requires timely sampling of blood and other biological specimens for clinical and forensic analysis. Endogenous concentrations of GHB in blood: GHB is both an endogenous metabolite and a drug of abuse, which complicates interpretation of the laboratory results of analysis. Moreover, the concentrations of GHB in blood and other specimens tend to increase after sampling, especially in autopsy cases. This requires the use of practical "cut-off" concentrations to avoid reporting false positive results. These cut-offs are different for different biological specimen types. Concentrations of GHB in clinical and forensic practice: As a recreational drug GHB is predominantly used by young males (94%) with a mean age of 27.1 years. The mean (median) and range of concentrations in blood from apprehended drivers was 90 mg/L (82 mg/L) and 8-600 mg/L, respectively. The concentration distributions in blood taken from living and deceased persons overlapped, although the mean (median) and range of concentrations were higher in intoxication deaths; 640 mg/L (280 mg/L) and 30-9200 mg/L, respectively. Analysis of GHB in alternative specimens: All biological fluids and tissue containing water are suitable for the analysis of GHB. Examples of alternative specimens discussed in this review are CSF, saliva, hair strands, breast milk, DBS, VH, and brain tissue.

CONCLUSIONS

Body fluids for the analysis of GHB must be obtained as quickly as possible after a poisoned patient is admitted to hospital or after a person is arrested for a drug-related crime to enhance chances of detecting the drug. The sampling of urine lengthens the window of detection by 3-4 h compared with blood samples, but with longer delays between last intake of GHB and obtaining specimens, hair strands, and/or nails might be the only option. In postmortem toxicology, the concentrations of drugs tend to be more stable in bladder urine, VH, and CSF compared with blood, because these sampling sites are protected from the spread of bacteria from the gut. Accordingly, the relationship between blood and urine concentrations of GHB furnishes useful information when drug intoxication deaths are investigated.

Presentations to an urban emergency department in Switzerland due to acute γ-hydroxybutyrate toxicity

Background

γ-Hydroxybutyrate (GHB) is a drug of abuse with dose-dependent sedative effects. Systematic data on the acute toxicity of GHB from emergency department (ED) presentations over a long period of time are currently missing from the literature. The present study described the clinical features of GHB toxicity.

Methods

Retrospective case series of GHB intoxications seen in an urban ED.

Results

From January 2002 to September 2015, 78 GHB-related intoxication cases were recorded (71 % male patients). The mean ± SD age was 29 ± 8 years. The co-use of alcohol and/or other illicit drugs was reported in 65 % of the cases. Neurological symptoms other than central nervous system depression included agitation (40 %) and clonus (21 %). The most frequent reasons for admission were coma (64 %) and agitation (23 %). The median time to regain consciousness was 90 min (range, 3–400 min). Sudden recovery was reported in 25 cases (32 %). Coma was not significantly associated with polyintoxication. Coma occurred in 77 % of the alcohol co-users and in 62 % ofthe non-alcohol users (p=0.052). The mean recovery time in comatose patients was 142 min in patients with co-use of alcohol compared with 89 min in patients without alcohol co-use (p=0.07). Alcohol co-use was not significantly associated with nausea/vomiting (p=0.07). The co-use of stimulants was not significantly associated with non-responsive coma (Glasgow Coma Scale = 3) or mean recovery time. Analytical confirmation of GHB was available in 37 cases (47 %), with additional quantitative analysis in 20 cases. The median GHB concentration was 240 mg/L (range, 8.3–373 mg/L). Intoxication was severe in 72 % of the cases. No fatalities occurred, and 72 % of the patients were discharged directly home from the ED.

Discussion

There were trend associations between alcohol co-use and frequency and length of coma and nausea/vomiting which did not reach the significance level (all p=0.05-0.07) but may nevertheless be clinically relevant. As the exact time of use is not always known, and co-use of other substances can affect the severity of poisoning, no definitive conclusions can be drawn regarding the association between GHB concentration and severity.

Conclusion

Impaired consciousness and agitation were typical findings of GHB intoxication. The co-use of alcohol and/or other illicit substances is common but was not significantly associated with the severity of the intoxications in our study.

The behavioural profile of gamma-hydroxybutyrate, gamma-butyrolactone and 1,4-butanediol in humans

Gamma-hydroxybutyrate (GHB) is a putative neurotransmitter, a drug of abuse, and a medical treatment for narcolepsy and other neuropsychiatric disorders. Its precursors gamma-butyrolactone (GBL) and 1,4-butanediol (1,4-BD) are endogenously converted to GHB and thereby exert their psychobehavioural effects. In humans, GHB has a wide spectrum of properties ranging from stimulation and euphoria in lower doses, to sedation, deep sleep, and coma after ingestion of high doses. However, behavioural studies in healthy volunteers remain scarce and are usually limited to psychomotor performance testing. Most available data arise from either qualitative studies with illicit users or clinical trials examining therapeutic properties of GHB (then usually termed sodium oxybate). Here, we present an overview of the behavioural effects of GHB, GBL, and 1,4-BD in these three populations. GHB and its precursors strongly influence behaviours related to core human autonomic functions such as control of food intake, sexual behaviour, and sleep-wake regulation. These effects are instrumentalised by illicit users and clinically utilised in neuropsychiatric disorders such as narcolepsy, fibromyalgia, and binge-eating syndrome. Considering the industry withdrawal from psychopharmacology development, repurposing of drugs according to their behavioural and clinical profiles has gained increasing relevance. As such, GHB seems to be an attractive candidate as an experimental therapeutic in depression.

GHB pharmacology and toxicology: acute intoxication, concentrations in blood and urine in forensic cases and treatment of the withdrawal syndrome

The illicit recreational drug of abuse, γ-hydroxybutyrate (GHB) is a potent central nervous system depressant and is often encountered during forensic investigations of living and deceased persons. The sodium salt of GHB is registered as a therapeutic agent (Xyrem®), approved in some countries for the treatment of narcolepsy-associated cataplexy and (Alcover®) is an adjuvant medication for detoxification and withdrawal in alcoholics. Trace amounts of GHB are produced endogenously (0.5-1.0 mg/L) in various tissues, including the brain, where it functions as both a precursor and a metabolite of the major inhibitory neurotransmitter γ-aminobutyric acid (GABA). Available information indicates that GHB serves as a neurotransmitter or neuromodulator in the GABAergic system, especially via binding to the GABA-B receptor subtype. Although GHB is listed as a controlled substance in many countries abuse still continues, owing to the availability of precursor drugs, γ-butyrolactone (GBL) and 1,4-butanediol (BD), which are not regulated. After ingestion both GBL and BD are rapidly converted into GHB (t½ ~1 min). The Cmax occurs after 20-40 min and GHB is then eliminated from plasma with a half-life of 30-50 min. Only about 1-5% of the dose of GHB is recoverable in urine and the window of detection is relatively short (3-10 h). This calls for expeditious sampling when evidence of drug use and/or abuse is required in forensic casework. The recreational dose of GHB is not easy to estimate and a concentration in plasma of ~100 mg/L produces euphoria and disinhibition, whereas 500 mg/L might cause death from cardiorespiratory depression. Effective antidotes to reverse the sedative and intoxicating effects of GHB do not exist. The poisoned patients require supportive care, vital signs should be monitored and the airways kept clear in case of emesis. After prolonged regular use of GHB tolerance and dependence develop and abrupt cessation of drug use leads to unpleasant withdrawal symptoms. There is no evidence-based protocol available to deal with GHB withdrawal, apart from administering benzodiazepines.

Effect of 3,4-methylenedioxymethamphetamine on the toxicokinetics and sedative effects of the drug of abuse, γ-hydroxybutyric acid

γ-Hydroxybutyric acid (GHB) is widely abused in combination with other club drugs such as 3,4-methylenedioxymethamphetamine (MDMA). The objectives of this study were to characterize the effects of MDMA on GHB toxicokinetics/toxicodynamics (TK/TD) and evaluate the use of monocarboxylate transporter (MCT) inhibition as a potential treatment strategy for GHB overdose when GHB is abused with MDMA. Rats were administered GHB 400 mg/kg i.v. alone or with MDMA (5 mg/kg i.v). Effects of MDMA and of the MCT inhibitor, l-lactate, on GHB TK and sedative effects were evaluated. The results of this study demonstrated no significant effect of MDMA on GHB TK or TD. GHB plasma concentrations were unchanged, and GHB concentration-effect relationships, based on plasma and brain concentrations and the return-to-righting reflex (RRR), were similar in the presence and absence of MDMA. l-Lactate administration resulted in a significant decrease in the sedative effect (RRR) of GHB when it was coadministered with MDMA. Our results indicate that MDMA does not affect the TK/TD of GHB at the doses used in this study, and MCT inhibition using l-lactate, an effective overdose treatment strategy for GHB alone, is also effective for GHB overdose when GHB is coingested with MDMA.

Screening and confirmation methods for GHB determination in biological fluids

The purpose of this review is to provide a comprehensive overview of reported methods for screening and confirmation of the low-molecular-weight compound and drug of abuse gamma-hydroxybutyric acid (GHB) in biological fluids. The polarity of the compound, its endogenous presence, its rapid metabolism after ingestion, and its instability during storage (de novo formation and interconversion between GHB and its lactone form gamma-butyrolactone) are challenges for the analyst and for interpretation of a positive result. First, possible screening procedures for GHB are discussed, including colorimetric, enzymatic, and chromatography-based procedures. Confirmation methods for clinical and forensic cases mostly involve gas chromatography (coupled to mass spectrometry), although liquid chromatography and capillary zone electrophoresis have also been used. Before injection, sample-preparation techniques include (a combination of) liquid-liquid, solid-phase, or headspace extraction, and chemical modification of the polar compound. Also simple "dilute-and-shoot" may be sufficient for urine or serum. Advantages, limitations, and trends are discussed.

Effects of monocarboxylate transporter inhibition on the oral toxicokinetics/toxicodynamics of γ-hydroxybutyrate and γ-butyrolactone

Respiratory depression and death secondary to respiratory arrest have occurred after oral overdoses of γ-hydroxybutyrate (GHB) and its precursor γ-butyrolactone (GBL). GHB is a substrate for monocarboxylate transporters (MCTs), and increasing GHB renal clearance or decreasing GHB absorption via MCT inhibition represents a potential treatment strategy for GHB/GBL overdose. In these studies, GHB and GBL were administered in doses of 1.92, 5.77, and 14.4 mmol/kg orally with and without MCT inhibition to determine effects of this treatment strategy on the oral toxicokinetics and toxicodynamics of GHB and GBL. The competitive MCT inhibitor l-lactate was administered by intravenous infusion starting 1 hour after GHB and GBL administration. Oral administration of l-lactate and the MCT inhibitor luteolin was also evaluated. Respiratory depression was measured using plethysmography. Intravenous l-lactate, but not oral treatments, significantly increased GHB renal and/or oral clearances. At the low dose of GHB and GBL, i.v. l-lactate increased GHB renal clearance. Due to the increased contribution of renal clearance to total clearance at the moderate dose, increased renal clearance translated to an increase in oral clearance. At the highest GHB dose, oral clearance was increased without a significant change in renal clearance. The lack of effect of i.v. l-lactate on renal clearance after a high oral GHB dose suggests possible effects of i.v. l-lactate on MCT-mediated absorption. The resulting increases in oral clearance improved respiratory depression. Intravenous l-lactate also reduced mortality with the high GBL dose. These data indicate i.v. l-lactate represents a potential treatment strategy in oral overdose of GHB and GBL.

The clinical toxicology of γ-hydroxybutyrate, γ-butyrolactone and 1,4-butanediol

INTRODUCTION

Gamma-hydroxybutyrate (GHB) and its precursors, gamma-butyrolactone (GBL) and 1,4-butanediol (1,4-BD), are drugs of abuse which act primarily as central nervous system (CNS) depressants. In recent years, the rising recreational use of these drugs has led to an increasing burden upon health care providers. Understanding their toxicity is therefore essential for the successful management of intoxicated patients. We review the epidemiology, mechanisms of toxicity, toxicokinetics, clinical features, diagnosis, and management of poisoning due to GHB and its analogs and discuss the features and management of GHB withdrawal.

METHODS

OVID MEDLINE and ISI Web of Science databases were searched using the terms "GHB," "gamma-hydroxybutyrate," "gamma-hydroxybutyric acid," "4-hydroxybutanoic acid," "sodium oxybate," "gamma-butyrolactone," "GBL," "1,4-butanediol," and "1,4-BD" alone and in combination with the keywords "pharmacokinetics," "kinetics," "poisoning," "poison," "toxicity," "ingestion," "adverse effects," "overdose," and "intoxication." In addition, bibliographies of identified articles were screened for additional relevant studies including nonindexed reports. Non-peer-reviewed sources were also included: books, relevant newspaper reports, and applicable Internet resources. These searches produced 2059 nonduplicate citations of which 219 were considered relevant.

EPIDEMIOLOGY

There is limited information regarding statistical trends on world-wide use of GHB and its analogs. European data suggests that the use of GHB is generally low; however, there is some evidence of higher use among some sub-populations, settings, and geographical areas. In the United States of America, poison control center data have shown that enquiries regarding GHB have decreased between 2002 and 2010 suggesting a decline in use over this timeframe.

MECHANISMS OF ACTION

GHB is an endogenous neurotransmitter synthesized from glutamate with a high affinity for GHB-receptors, present on both on pre- and postsynaptic neurons, thereby inhibiting GABA release. In overdose, GHB acts both directly as a partial GABA(b) receptor agonist and indirectly through its metabolism to form GABA.

TOXICOKINETICS

GHB is rapidly absorbed by the oral route with peak blood concentrations typically occurring within 1 hour. It has a relatively small volume of distribution and is rapidly distributed across the blood-brain barrier. GHB is metabolized primarily in the liver and is eliminated rapidly with a reported 20-60 minute half-life. The majority of a dose is eliminated completely within 4-8 hours. The related chemicals, 1,4-butanediol and gamma butyrolactone, are metabolized endogenously to GHB. CLINICAL FEATURES OF POISONING: GHB produces CNS and respiratory depression of relatively short duration. Other commonly reported features include gastrointestinal upset, bradycardia, myoclonus, and hypothermia. Fatalities have been reported. MANAGEMENT OF POISONING: Supportive care is the mainstay of management with primary emphasis on respiratory and cardiovascular support. Airway protection, intubation, and/or assisted ventilation may be indicated for severe respiratory depression. Gastrointestinal decontamination is unlikely to be beneficial. Pharmacological intervention is rarely required for bradycardia; however, atropine administration may occasionally be warranted. WITHDRAWAL SYNDROME: Abstinence after chronic use may result in a withdrawal syndrome, which may persist for days in severe cases. Features include auditory and visual hallucinations, tremors, tachycardia, hypertension, sweating, anxiety, agitation, paranoia, insomnia, disorientation, confusion, and aggression/combativeness. Benzodiazepine administration appears to be the treatment of choice, with barbiturates, baclofen, or propofol as second line management options.

CONCLUSIONS

GHB poisoning can cause potentially life-threatening CNS and respiratory depression, requiring appropriate, symptom-directed supportive care to ensure complete recovery. Withdrawal from GHB may continue for up to 21 days and can be life-threatening, though treatment with benzodiazepines is usually effective.

Long-term stability of GHB in post-mortem samples and samples from living persons, stored at -20°C, using fluoride preservatives

PURPOSE

Reanalyses are frequently requested in forensic toxicology, and knowledge of the stability of drugs in biological samples is of major importance for the interpretation of the toxicological findings. Currently, the literature on stability of gammahydroxybutyrate (GHB) in blood samples from living subjects and in post-mortem blood is limited. The purpose of this study was to evaluate the long-term stability of GHB in both blood samples from persons suspected of drug use and post-mortem blood samples.

METHODS

A total of 59 reanalyses were performed in whole blood samples, 27 samples from living subjects and 32 samples taken at autopsies. The samples were stored in the freezer between 0.4 and 7.2 years at -20°C in vials containing preservatives. Analyses were performed by GC-FID, and cut-off level was 10.3 mg/L. The concentrations in 22 of the samples were below cut-off.

RESULTS

The mean change in concentration between initial analysis and reanalysis was -0.8% for the positive samples from living persons and -7.1% for the positive post-mortem samples. Changes ranged from -32.4% to 21.0% for samples from living and from -30.4% to 34.4% for post-mortem samples. All negative samples were still negative at the time of reanalysis.

CONCLUSION

Reanalysis of these forensic whole blood samples stored several years at -20°C with fluoride preservation did not exhibit changes in GHB concentrations of practical significance for the interpretation of toxicological findings.

Absorption, distribution, metabolism and excretion pharmacogenomics of drugs of abuse

Pharmacologic and toxic effects of xenobiotics, such as drugs of abuse, depend on the genotype and phenotype of an individual, and conversely on the isoenzymes involved in their metabolism and transport. The current knowledge of such isoenzymes of frequently abused therapeutics such as opioids (oxycodone, hydrocodone, methadone, fentanyl, buprenorphine, tramadol, heroin, morphine and codeine), anesthetics (γ-hydroxybutyric acid, propofol, ketamine and phencyclidine) and cognitive enhancers (methylphenidate and modafinil), and some important plant-derived hallucinogens (lysergide, salvinorin A, psilocybin and psilocin), as well as of nicotine in humans are summarized in this article. The isoenzymes (e.g., cytochrome P450, glucuronyltransferases, esterases and reductases) involved in the metabolism of drugs and some pharmacokinetic data are discussed. The relevance of such data is discussed for predicting possible interactions with other xenobiotics, understanding pharmacokinetic behavior and pharmacogenomic variations, assessing toxic risks, developing suitable toxicological analysis procedures, and finally for interpretating drug testing results.

Monocarboxylate Transporter Inhibition with Osmotic Diuresis Increases γ-Hydroxybutyrate Renal Elimination in Humans: A Proof-of-Concept Study

BACKGROUND AND OBJECTIVE

The purpose of the current study was to demonstrate proof-of-concept that monocarboxylate transporter (MCT) inhibition with L-lactate combined with osmotic diuresis increases renal clearance of γ-hydroxybutyrate (GHB) in human subjects. GHB is a substrate for human and rodent MCTs, which are responsible for GHB renal reabsorption, and this therapy increases GHB renal clearance in rats.

METHODS

Ten healthy volunteers were administered GHB orally as sodium oxybate 50 mg/kg (4.5 gm maximum dose) on two different study days. On study day 1, GHB was administered alone. On study day 2, treatment of L-lactate 0.125 mmol/kg and mannitol 200 mg/kg followed by L-lactate 0.75 mmol/kg/hr was administered intravenously 30 minutes after GHB ingestion. Blood and urine were collected for 6 hours, analyzed for GHB, and pharmacokinetic and statistical analyses performed.

RESULTS

L-lactate/mannitol administration significantly increased GHB renal clearance compared to GHB alone, 439 vs. 615 mL/hr (P=0.001), and increased the percentage of GHB dose excreted in the urine, 2.2 vs. 3.3% (P=0.021). Total clearance was unchanged.

CONCLUSIONS

MCT inhibition with L-lactate combined with osmotic diuresis increases GHB renal elimination in humans. No effect on total clearance was observed in this study due to the negligible contribution of renal clearance to total clearance at this low GHB dose. Considering the nonlinear renal elimination of GHB, further research in overdose cases is warranted to assess the efficacy of this treatment strategy for increasing renal and total clearance at high GHB doses.

Twenty-three deaths with gamma-hydroxybutyrate overdose in western Sweden between 2000 and 2007

BACKGROUND

gamma-Hydroxybutyrate (GHB) is a drug of abuse with a status as being safe. In spite of a reputation of low toxicity, a huge number of deaths associated with this drug have been recorded during recent years in Sweden. It is unclear whether coingestion with other drugs or ethanol causes death in GHB overdoses or whether GHB itself is the main cause of death.

OBJECTIVES

The aim of this study was to analyze the cause of death in GHB-related fatalities seen in our region.

METHODS

All cases of deaths with GHB during the year 2000-2007 in the region of western Sweden were studied retrospectively. The cases were classified as either GHB poisonings without any, with a minor or a major influence of other drugs on the cause of death.

RESULTS

Twenty-three cases were diagnosed as deaths due to GHB overdose. Ninety-one percent coingested other substances. Ninety-one percent of the decedents were male. Age varied between 16 and 46, with the median age at 25 years. Forty-three percent of the cases were classified as GHB poisonings without any or a minor influence of other drugs on the cause of death. Thirty percent also ingested ethanol. Two patients (9%) were only intoxicated with GHB.

CONCLUSIONS

Intoxication with GHB carries some mortality. Combining GHB with ethanol does not explain the many deaths in our region, nor do extremely high plasma concentrations of GHB. The intake of opioids increases the toxicity of GHB. The drug itself has such biological activities that an overdose is dangerous and may lead to death.

Postmortem toxicology

Results from toxicological analyses in death investigations are used to determine whether foreign substances were a cause of death, whether they contributed to death, or whether they caused impairment. Drug concentrations are likely to change during pre-terminal stages due to altered pharmacokinetics, to treatment during resuscitation or in the intensive care unit, to concomitant illness or to the presence of drug tolerance. The potential for postmortem changes must be considered in all but a few drugs. Formation of new entities as well as degradation of drugs may occur, especially in putrefied corpses; in addition, body fluids and tissues may be severely affected by autolysis and putrefaction. Specimens should be selected based on individual case history and on their availability. Analytical procedures should be performed in accordance with a proper quality assurance program for toxicological investigations. Problems are most likely to occur during the isolation and identification of a drug. Interpretation of analytical results is often limited by the inadequate information provided in a particular case.