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.

Cognitive Impairment Following Clinical or Recreational Use of Gammahydroxybutyric Acid (GHB): A Systematic Review

BACKGROUND

GHB (gamma-hydroxybutyric acid; sodium oxybate) is a general anaesthetic that is clinically used for the treatment of narcolepsy, cataplexy, alcohol withdrawal and alcohol relapse prevention. In addition, GHB is recreationally used. Most clinical and recreational users regard GHB as an innocent drug devoid of adverse effects, despite its high dependence potential and possible neurotoxic effects. At high doses, GHB may lead to a comatose state. This paper systematically reviews possible cognitive impairments due to clinical and recreational GHB use.

METHODS

PubMed and PsychINFO were searched for literature data about the acute and residual cognitive deficits following GHB use. This review is conducted using the PRISMA protocol.

RESULTS

A total of 43 reports covering human and animal data on GHB-induced cognitive impairments were eligible and reviewed. This systematic review found no indication for cognitive impairments after clinical GHB use. However, it supports the view that moderate GHB use may result in acute short-term cognitive impairments, whereas regular high-dose GHB use and/or multiple GHB-induced comas are probably neurotoxic resulting in long-term residual cognitive impairments.

CONCLUSION

These results emphasize the need for awareness among clinicians and recreational users to minimize negative health consequences of recreational GHB use, particularly when high doses are used and GHB-induced comas occur.

Unity in diversity: A systematic review on the GHB using population

BACKGROUND

Over the past decades gamma-hydroxybutyrate (GHB) has emerged as a popular drug with high potential of (ab)use due to its euphoric and relaxing effects. An overview of different populations using GHB is urgently needed, since this would enable development of adequate prevention and treatment policies to diminish the risks associated with GHB use. We systematically reviewed literature on different GHB using populations, comparing demographic characteristics, GHB use patterns, psychosocial aspects and psychiatric comorbidity.

METHODS

We conducted a systematic review following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines using Rayyan software. Original studies published from January 1997 up to October 2019 on GHB use were included. Out of 80 full-text articles, 60 articles of 51 unique studies were included. Most studies included people using GHB 1) presenting at emergency departments (n = 22), 2) recruited from the general population (n = 11), or 3) presenting at addiction care (n = 8).

RESULTS

Three main sub-populations of people using GHB are described in the literature: people using GHB recreationally without adverse effects; people using GHB recreationally with adverse effects, and people with dependence on GHB. These groups show considerable overlap in gender, age range, and comorbid substance use, as well as amount of GHB use per occasion. Differences are related to frequency and function of GHB use, the number of comas experienced, as well as work status, and psychiatric comorbidity.

CONCLUSION

Policy interventions should aim at preventing the transition from recreational substance use to GHB use, as most users are experienced recreational substance users prior to starting GHB use. When people use GHB regularly, interventions should aim at reducing the level of GHB use and preventing GHB use-related harm. Longitudinal studies and population-based probability sampling are required for more insight in the dynamics of GHB use in different sub-populations, and the transition from one group to the other, ultimately leading to dependence on GHB.

Trends in gamma-hydroxybutyrate-related harms based on ambulance attendances from 2012 to 2018 in Victoria, Australia

BACKGROUND AND AIMS

Although the prevalence of gamma-hydroxybutyrate (GHB) use is relatively low globally, harms related to the drug appear to be increasing. Few existing studies present reliable, representative, population-level data on GHB-related harms. The aim of this study was to investigate trends in acute GHB-related harms within an ambulance database in Australia.

DESIGN, SETTING AND PARTICIPANTS

Cross-sectional, retrospective analysis of data on all GHB-related ambulance attendances in the state of Victoria, Australia during a 7-year period (January 2012-December 2018) MEASUREMENTS: Presentations were characterized based on patient demographics, transport to hospital, co-occurring substance use (i.e. GHB only, alcohol, methamphetamine, heroin, benzodiazepine and cannabis) and clinical presentation (e.g. symptoms of anxiety, psychosis, depression).

FINDINGS

There were 5866 GHB-related ambulance attendances between 2012 and 2018, with the prevalence rate increasing from 8.8 per 100 000 population in 2012 to a maximum of 21.7 per 100 000 population in 2017. Methamphetamine [odds ratio (OR) = 6.23, P < 0.001] and benzodiazepine-related (OR = 1.43, P < 0.001) co-occurrences; ages between 18-29 (OR = 6.58, P < 0.001) and 30-39 years (OR = 2.02, P < 0.001); and male gender (OR = 1.23, P < 0.001) were significant predictors of GHB-related attendances.

CONCLUSIONS

There has been a 147% increase in the prevalence of GHB-related ambulance attendances in Victoria, Australia between 2012 and 2019, largely attributable to a growth in the proportions of people using gamma-hydroxybutyrate alone or concurrently with methamphetamine.

Comparing rates and characteristics of ambulance attendances related to extramedical use of pharmaceutical opioids in Australia: a protocol for a retrospective observational study

INTRODUCTION AND AIMS

Extramedical use of, and associated harms with pharmaceutical opioids are common. Analysis of coded ambulance clinical records provides a unique opportunity to examine a national population-level indicator of relative harms. This protocol describes an observational study with three aims: (1) to compare supply adjusted rates of pharmaceutical opioid-related ambulance attendances for buprenorphine, codeine, fentanyl, oxycodone, oxycodone-naloxone, morphine, pethidine, tramadol and tapentadol; (2) to compare presentation characteristics for these commonly used pharmaceutical opioids and (3) to describe the context surrounding ambulance presentations related to oxycodone, a widely used opioid with an established abuse liability, and tapentadol, a more recent 'atypical' opioid on the Australian market, with fewer studies that have directly examined signals of extramedical use.

METHOD

Trained coders extract data from clinical records for ambulance presentations relating to extramedical use of commonly used pharmaceutical opioids. These data form the basis of a large, national database that captures alcohol-related and drug-related harms. Supply adjusted rates of presentations will be examined using Poisson regression. Multinomial logistic regression will be used to compare severity and other characteristics of attendances relating to different pharmaceutical opioids. Tapentadol-related and oxycodone-related cases will be qualitatively examined to understand the situationally specific contexts of the ambulance attendances outside of the characteristics captured in routinely coded variables.

ETHICS AND DISSEMINATION

Ethics approval related to analysis of ambulance attendance data was obtained from the Eastern Health Human Research Ethics Committee (E122 08-09), with an amendment specific to the qualitative analysis. Findings will be submitted for peer review in 2019. The understanding of risk profiles in real-world settings is of international public health importance. The analysis and publication of findings from this national dataset of clinical records will provide one of the most nuanced analyses to date of relative harms across nine pharmaceutical opioids over a 6-year period.

Harm reduction strategies related to dosing and their relation to harms among festival attendees who use multiple drugs

INTRODUCTION AND AIMS

Polysubstance users are a high-risk population for negative health-related consequences. Although some studies have described harm reduction strategies adopted by polysubstance users, studies have not examined their effectiveness in minimising health-related consequences. We aimed to identify dosing-related harm reduction strategies in a sample of polysubstance-using dance festival attendees, and explore the relationship between harm reduction strategies and self-reported adverse health consequences.

DESIGN AND METHODS

Data were examined for 1226 past-year dance festival attendees who self-identified as past-year multiple drug users. We conducted bivariable and multivariable analyses to explore relationships between six dosing-related harm reduction strategies and 13 self-reported adverse consequences.

RESULTS

Self-reported use of dosing-related harm reduction strategies was prevalent, mainly avoidance of mixing depressants (69.2%) and setting limits on quantity (62.2%). Frequent users of harm reduction strategies reported experiencing fewer adverse health consequences (P values < 0.05). Those who reportedly set limits on quantity were at decreased odds of experiencing a bad mood after drug use, sexual difficulties while under drug influence, injuries or fractures while under drug influence, and involvement in fights or being attacked while under drug influence (P values < 0.05). Moreover, those who report frequently avoid mixing depressants were at decreased odds of experiencing headache, loss of consciousness, drop in blood pressure, injuries of fractures, and fights or attacks (P values < 0.05).

DISCUSSION AND CONCLUSIONS

Adoption of dosing-related harm reduction strategies appears to be associated with less drug-related harm among polysubstance-using festival attendees. Findings may inform organisations and policymakers in the designing of harm reduction interventions with this population.

Trends in cannabis-related ambulance presentations from 2000 to 2013 in Melbourne, Australia

AIMS

The current burden of cannabis-related presentations to emergency health services is largely unknown. This paper presents data collected over a 13-year period in metropolitan Melbourne, Australia as part of the Ambo Project, a unique surveillance system that analyses and codes paramedic records for drug-related trends and harms.

METHODS

Cannabis-related ambulance attendances involving 15-59 year olds in metropolitan Melbourne were analysed retrospectively from 2000 to 2013 (n=10,531). Trends and attendance characteristics were compared among cannabis only (CO)-, cannabis and alcohol (CA)- and cannabis with polydrug use (CP)-related attendances. Changes in alcohol and drug involvements in cannabis-related attendances were explored.

RESULTS

Rates of cannabis-related ambulance attendances increased significantly over the study period. Increasing rate of attendances per 100,000 population per year changed from 0.6 (2000-2010) to 5.5 (2010-2013). This sharp change was driven by CO- and CP-related attendances (rate of CA-related attendance increased steadily). The highest increasing rate (15.6) was for CO-related attendances among 15-29 years old males (2010-2013). Crystal methamphetamine became the most common illicit co-intoxicant amongst cannabis presentations in 2013.

CONCLUSIONS

Relative to the total drug-related burden on ambulance services, cannabis-related presentations appear to be a small but significant and increasing problem. Significant changes in trends across other drug involvement and demographic subgroups suggest a possible shift in the cannabis using population and/or a change in using behaviours. Public health strategies should raise awareness of the increased risk posed by cannabis polydrug use and high attendance subpopulations should be determined.

Effect of intubation for gamma-hydroxybutyric acid overdose on emergency department length of stay and hospital admission

OBJECTIVES

The objective was to examine the effect of endotracheal intubation on emergency department (ED) length of stay (LOS) and admission rates for patients with gamma-hydroxybutyrate (GHB) overdose.

METHODS

A 3-year retrospective electronic and paper audit of recreational drug presentations was carried out at two major inner-city EDs in Melbourne, Australia. Different GHB overdose management strategies exist at the respective audit sites, namely: 1) all patients with a Glasgow Coma Scale (GCS) score of 8 or less are intubated or 2) uncomplicated patients with GCS scores of 8 or less are managed without intubation (conservative management), unless further complications arise. This difference allows for comparison of the effects of intubation. All suspected GHB-related cases (defined as cases where GHB or its analogs gamma-butyrolactone or 1,4-butanediol were recorded) in which altered consciousness state was noted as a presenting symptom at triage were selected from all recreational drug-related presentations occurring between January 2008 and December 2010. The relationship between intubation and the primary outcome, ED LOS, was examined using robust regression after adjustment for potential confounders. The relationship between intubation and admission status (admission to hospital versus discharge) was also examined using logistic regression.

RESULTS

After adjustment for potential confounders such as GCS score, intubation of GHB-related cases in the ED was associated with an increase in mean LOS of 41% (95% confidence interval [CI] = 19% to 65%) and an increase in the odds of admission to hospital of 9.95 (95% CI = 2.36 to 41.88) at one hospital site, compared to conservative airway management.

CONCLUSIONS

Conservative airway management (no intubation) is associated with shorter ED LOS in cases of uncomplicated GHB-related coma in the ED and may also be associated with lower admission rates for these patients.

Risk factors of γ-hydroxybutyrate overdosing

The aim of this study was to identify in recreational drug users the factors which increase the risk of overdosing (OD) with γ-hydroxybutyrate (GHB). A purposive sample of 45 experienced GHB users was interviewed, equally divided into three groups (never OD, occasional OD, and repeat OD). The repeat OD group scored highest on many risk factors regarding GHB use, the occasional OD group scored intermediate, and the never OD group scored lowest. Participants, whether or not they had overdosed on GHB, most often perceived GHB use (e.g. using more GHB than usual, using GHB doses too closely together) as the main reason for GHB OD, and many participants who had overdosed on GHB reported that they had taken more GHB than usual at their most recent occasion of GHB OD. No significant differences in co-use of GHB with other substances were found between the three groups. Our findings indicate that using GHB in the company of groups of friends probably reduces, but does not eliminate, the risk of OD.

Nurse's perspectives on care provided for patients with gamma-hydroxybutyric acid and gamma-butyrolactone abuse

AIMS AND OBJECTIVES

To describe registered nurses' views and experiences providing care for gamma-hydroxybutyric acid and gamma-butyrolactone abuse inpatients in a psychiatric unit.

BACKGROUND

Gamma-hydroxybutyric acid and gamma-butyrolactone are illegal drugs with potentially fatal outcomes that are entering wider use in Scandinavia. Gamma-hydroxybutyric acid-dependent persons with withdrawal symptoms often require forceful withdrawal treatment provided in psychiatric units.

DESIGN

A qualitative study with a purposive sample including interviews from registered nurses.

METHODS

Data were collected from interviews with 15 registered nurses working in specialised dependency units in psychiatric wards. The data collected were analysed through a descriptive, qualitative analysis.

RESULTS

The registered nurses' narratives revealed four main areas of convergence: feelings of anxiety and despair, preparation for unpredictable and precarious situations, striving for good relationship and striving to optimise and develop nursing care. The interviews revealed that registered nurses reflect on and discuss their feelings about their patients' situations with colleagues; prepare themselves for potential aggressiveness and unpredictable situations; improve their care through conscious attitude adjustment and relationship-forming behaviours; and strive to increase their personal knowledge, maintain a hopeful outlook and exhibit a positive approach. These themes were found in all nine categories and sixteen subcategories.

DISCUSSION

The findings based on the registered nurses' narratives indicated that the registered nurses experienced their work situation when caring for these patients to be very complex and demanding.

CONCLUSION

The study revealed that registered nurses worked extensively to craft their approach and attitude towards their patients. It is clear that registered nurses use themselves as tools or instruments for the creation of good relationships, thus providing the best care possible.

RELEVANCE TO CLINICAL PRACTICE

Registered nurses should be given more education, clearer guidelines and better guidance to assist them in facing such challenging and often problematic situations. One-on-one shadowing provides the possibility to create and develop relationship.

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.

Hospital in the Field: Prehospital Management of GHB Intoxication by Medical Assistance Teams

Introduction

Recreational use of gamma-hydroxybutyrate (GHB) is increasingly common at mass-gathering dance events in Australia. Overdose often occurs in clusters, and places a significant burden on the surrounding health care infrastructure.

Objective

To describe the clinical presentation, required interventions and disposition of patrons with GHB intoxication at dance events, when managed by dedicated medical assistance teams.

Methods

Retrospective analysis of all patrons attending St. John Ambulance medical assistance teams at dance events in the state of Victoria (Australia), from January 2010 through May 2011.

Main outcome measures

Clinical presentation, medical interventions and discharge destination.

Results

Sixty-one patients with GHB intoxication attended medical teams during the study period. The median age was 22 years, and 64% were male. Altered conscious state was present in 89% of attendances, and a GCS <9 in 44%. Hypotension, bradycardia and hypothermia were commonly encountered. Endotracheal intubation was required in three percent of patrons. Median length of stay onsite was 90 minutes. Ambulance transport to hospital was avoided in 65% of presentations.

Conclusions

The deployment of medical teams at dance events and music festivals successfully managed the majority of GHB intoxications onsite and avoided acute care ambulance transfer and emergency department attendance.

DutchMJ,AustinKB.Hospital in the field: prehospital management of GHB intoxication by medical assistance teams.Prehosp Disaster Med.2012;27(4):1-5.

Possible long-term effects of γ-hydroxybutyric acid (GHB) due to neurotoxicity and overdose

In several countries, including the Netherlands, the use of GHB seems to be rising. GHB is regarded by recreational users as an innocent drug without any side effects. Recently, the number of patients in treatment due to GHB addiction sharply increased. In addition, various studies report incidents following risky GHB use or GHB overdosing. Other sedative drugs, like ketamine and alcohol have been shown to result in unintended neurotoxic harm at the level of memory and cognitive function. As outlined in the present review, GHB and ketamine have a common mode of action, which suggests that GHB may also lead to similar neurotoxicity as ketamine. GHB overdosing, as well as binge drinking (and high ketamine doses), induce profound coma which is probably neurotoxic for the brain especially in the maturing brain of young adults. It is therefore advocated to investigate possible long-term neurotoxic effects in recreational GHB users e.g. by studying the residual effects on cognition and memory.

Temporal differences in γ-hydroxybutyrate overdoses involving injecting drug users versus recreational drug users in Helsinki: a retrospective study

Background

Gamma-hydroxybutyrate (GHB) and gamma-butyrolactone (GBL) have been profiled as 'party drugs' used mainly at dance parties and in nightclubs on weekend nights. The purpose of this study was to examine the frequency of injecting drug use among GHB/GBL overdose patients and whether there are temporal differences in the occurrence of GHB/GBL overdoses of injecting drug and recreational drug users.

Methods

In this retrospective study, the ambulance and hospital records of suspected GHB- and GBL overdose patients treated by the Helsinki Emergency Medical Service from January 1^st 2006 to December 31^st 2007 were reviewed. According to the temporal occurrence of the overdose, patients were divided in two groups. In group A, the overdose occurred on a Friday-Saturday or Saturday-Sunday night between 11 pm-6 am. Group B consisted of overdoses occurring on outside this time frame.

Results

Group A consisted of 39 patient contacts and the remaining 61 patient contacts were in group B. There were statistically significant differences between the two groups in (group A vs. B, respectively): history of injecting drug abuse (33% vs. 59%, p = 0.012), reported polydrug and ethanol use (80% vs. 62%, p = 0.028), the location where the patients were encountered (private or public indoors or outdoors, 10%, 41%, 41% vs. 25%, 18%, 53%, p = 0.019) and how the knowledge of GHB/GBL use was obtained (reported by patient/bystanders or clinical suspicion, 72%, 28% vs. 85%, 10%, p = 0.023). Practically all (99%) patients were transported to emergency department after prehospital care.

Conclusion

There appears to be at least two distinct groups of GHB/GBL users. Injecting drug users represent the majority of GHB/GBL overdose patients outside weekend nights.

Mechanistic toxicokinetic model for gamma-hydroxybutyric acid: inhibition of active renal reabsorption as a potential therapeutic strategy

gamma-Hydroxybutyric acid (GHB), a drug of abuse, exhibits saturable renal clearance and capacity-limited metabolism. The objectives of this study were to construct a mechanistic toxicokinetic (TK) model describing saturable renal reabsorption and capacity-limited metabolism of GHB and to predict the effects of inhibition of renal reabsorption on GHB TK in the plasma and urine. GHB was administered by iv bolus (200-1,000 mg/kg) to male Sprague-Dawley rats and plasma and urine samples were collected for up to 6 h post-dose. GHB concentrations were determined by LC/MS/MS. GHB plasma concentration and urinary excretion were well-described by a TK model incorporating plasma and kidney compartments, along with two tissue and two ultrafiltrate compartments. The estimate of the Michaelis-Menten constant for renal reabsorption (K (m,R)) was 0.46 mg/ml which is consistent with in vitro estimates of monocarboxylate transporter (MCT)-mediated uptake of GHB (0.48 mg/ml). Simulation studies assessing inhibition of renal reabsorption of GHB demonstrated increased time-averaged renal clearance and GHB plasma AUC, independent of the inhibition mechanism assessed. Co-administration of GHB (600 mg/kg iv) and L: -lactate (330 mg/kg iv bolus plus 121 mg/kg/h iv infusion), a known inhibitor of MCTs, resulted in a significant decrease in GHB plasma AUC and an increase in time-averaged renal clearance, consistent with the model simulations. These results suggest that inhibition of renal reabsorption of GHB is a viable therapeutic strategy for the treatment of GHB overdoses. Furthermore, the mechanistic TK model provides a useful in silico tool for the evaluation of potential therapeutic strategies.

Case series of 226 γ-hydroxybutyrate-associated deaths: lethal toxicity and trauma

γ-Hydroxybutyrate (GHB) and its prodrugs are drugs of abuse that were also sold as "dietary supplements." Users present to emergency departments with overdose, impaired driving, withdrawal, and associated trauma. We compiled a series of GHB-associated deaths to elucidate lethal risks, GHB concentrations, cointoxicants, products, uses, and medical interventions. Death records were reviewed for toxicology, autopsy findings, and history. Inclusion cutoffs were as follows: 5/10 mg/L of GHB (antemortem blood/urine) and 50/20/7 mg/L of GHB (postmortem blood/urine/vitreous). Of 226 deaths included, 213 had cardiorespiratory arrest and 13 had fatal accidents. Seventy-eight deaths (35%) had no cointoxicants. Sixteen deaths involved "supplements" and 1 involved pharmaceutical GHB (Xyrem, Jazz Pharmaceuticals, Palo Alto, CA). Postmortem blood GHB was 18 to 4400 mg/L (median, 347 mg/L) in deaths negative for cointoxicants. Cardiorespiratory arrest occurred prehospital in 100% of 184 cases with available history. Of 72 cases with antemortem adverse effects reported, medical assistance was delayed or absent in 66; of these, acute GHB ingestion was known in 51, including 40 left to "sleep off" adverse effects. Thirty others were left "sleeping" and found dead. γ-Hydroxybutyrate is lethal even without cointoxicants, directly and through fatal accidents. Medical interventions were frequently delayed or absent despite known GHB ingestion, and witnessed adverse events and cardiorespiratory arrest occurred prehospital. Education is needed about the lethality of GHB and the necessity for prompt medical intervention.

A review of tolerability and abuse liability of gamma-hydroxybutyric acid for insomnia in patients with schizophrenia

BACKGROUND

Approved therapeutic uses for gamma-hydroxybutyric acid (GHB) (or sodium oxybate), a gamma-aminobutyric acid type B and GHB receptor agonist, include narcolepsy in the United States and Europe and alcohol abuse treatment in Italy. Possible efficacy of GHB in schizophrenia has also been proposed. A tolerability concern regarding use of GHB is its abuse potential. Given the high comorbidity of substance disorders and schizophrenia, a systematic assessment of the published literature is crucial.

OBJECTIVE

The aim of this review was to assess the tolerability and abuse liability of GHB in the context of future clinical studies as a potential treatment for insomnia in patients with schizophrenia.

METHODS

A literature search in English (inception through April 2009, inclusive) was conducted of MEDLINE, EMBASE, and PsycINFO using the search term GHB. All articles whose abstracts mentioned human use of GHB were read in their entirety. The reference sections of identified articles were reviewed for publications that might have been missed by the initial search.

RESULTS

GHB is abused by a small percentage of people (<1%) as a "club drug" and is commonly associated with enhanced sexual experiences (65%), euphoria (41%), somnolence (71%), and confusion (24%), according to a recent study. A review of all available emergency room case series suggests that while GHB can be associated with serious coma necessitating intubation, the number of reported fatal cases associated with GHB appears limited. Clarity on the lethality of GHB is complicated by instability of GHB in postmortem samples and frequent concomitant ingestions. Furthermore, formal abuse liability studies do not support high abuse propensity for GHB, mainly because oversedation and dizziness may lead most individuals to find GHB unpleasant at high doses. As supported by 2 large studies, there is limited evidence to suggest widespread use as an agent in sexual assault. Years of clinical use in narcolepsy do not support the development of tolerance or withdrawal in those subjects without substance dependence.

CONCLUSIONS

Tolerability and abuse liability issues, while a concern with GHB given its abuse potential, do not preclude further study of the potential use for insomnia in nondually diagnosed schizophrenia. Full cognizance must be taken of risk/benefit tradeoffs, and to the development of improved formulations with decreased abuse liability.

Illicit gamma-hydroxybutyrate (GHB) and pharmaceutical sodium oxybate (Xyrem): differences in characteristics and misuse

There are distinct differences in the accessibility, purity, dosing, and misuse associated with illicit gamma-hydroxybutyrate (GHB) compared to pharmaceutical sodium oxybate. Gamma-hydroxybutyrate sodium and sodium oxybate are the chemical and drug names, respectively, for the pharmaceutical product Xyrem (sodium oxybate) oral solution. However, the acronym GHB is also used to refer to illicit formulations that are used for non-medical purposes. This review highlights important differences between illicit GHB and sodium oxybate with regard to their relative abuse liability, which includes the likelihood and consequences of abuse. Data are summarized from the scientific literature; from national surveillance systems in the U.S., Europe, and Australia (for illicit GHB); and from clinical trials and post-marketing surveillance with sodium oxybate (Xyrem). In the U.S., the prevalence of illicit GHB use, abuse, intoxication, and overdose has declined from 2000, the year that GHB was scheduled, to the present and is lower than that of most other licit and illicit drugs. Abuse and misuse of the pharmaceutical product, sodium oxybate, has been rare over the 5 years since its introduction to the market, which is likely due in part to the risk management program associated with this product. Differences in the accessibility, purity, dosing, and misuse of illicit GHB and sodium oxybate suggest that risks associated with illicit GHB are greater than those associated with the pharmaceutical product sodium oxybate.

Gamma-hydroxybutyrate withdrawal syndrome: dangerous but not well-known

Gamma-hydroxybutyrate (GHB) is an endogenous inhibitory neurotransmitter and anesthetic agent that is being abused as a 'club drug.' Withdrawal symptoms after cessation of GHB use are common and depend on the intensity of use. However, GHB withdrawal syndrome and delirium are unfamiliar to most psychiatrists, probably due to the fact that neither textbooks nor guidelines cover the subject. The GHB withdrawal syndrome may have a fulminant course that progresses to delirium. In those severe cases, admission to a general hospital and involvement of a psychiatrist become necessary. We present two cases of severe GHB withdrawal delirium, provide an overview of the literature and conclude with treatment recommendations.

The distribution of gamma-hydroxybutyrate-induced Fos expression in rat brain: comparison with baclofen

gamma-Hydroxybutyrate (GHB) is a euphoric, prosocial and sleep inducing drug that binds with high affinity to its own GHB receptor site and also more weakly to GABA(B) receptors. GHB is efficacious in the treatment of narcolepsy and alcoholism, but heavy use can lead to dependence and withdrawal. Many effects of GHB (sedation, hypothermia, catalepsy) are mimicked by GABA(B) receptor agonists (e.g. baclofen). However other effects (euphoric and prosocial effects and a therapeutic effect in narcolepsy) are not. The present study used Fos immunohistochemistry to assess the neural activation produced in rat brain by medium to high doses of GHB (250, 500 and 1000 mg/kg) and a high dose of baclofen (10 mg/kg) that produced similar sedation to 500 mg/kg GHB. Results showed many common regions of activation with these two drugs including the supraoptic, paraventricular, median preoptic and ventral premammillary nuclei of the hypothalamus, the central nucleus of the amygdala, Edinger-Westphal nucleus, lateral parabrachial nucleus, locus coeruleus, and nucleus of the solitary tract. GHB (500 mg/kg), but not baclofen (10 mg/kg), induced significant Fos expression in the median raphe nucleus and lateral habenula, while a higher dose of GHB (1000 mg/kg) induced additional Fos expression in the islands of Calleja, dentate gyrus (polymorphic layer) and arcuate nucleus, and in various regions implicated in rapid and non-rapid eye movement sleep (laterodorsal tegmental nucleus, tuberomammillary nucleus and the ventrolateral and anterodorsal preoptic nuclei). Surprisingly, Fos immunoreactivity was not observed with either GHB or baclofen in reward-relevant regions such as the nucleus accumbens, striatum and ventral tegmental area. Overall these results indicate a distinctive signature of brain activation with GHB that may be only partly due to GABA(B) receptor effects. This confirms a unique neuropharmacological profile for GHB and indicates key neural substrates that may underlie its characteristic influence on sleep, body temperature, sociability and endocrine function.