Hair testing of GHB: an everlasting issue in forensic toxicology

BACKGROUND

In this paper, the authors present a critical review of different studies regarding hair testing of endogenous γ-hydroxybutyrate (GHB), concentrations in chronic users, and values measured after a single GHB exposure in drug facilitated sexual assault (DFSA) cases together with the role of a recently identified GHB metabolite, GHB-glucuronide.

CONTENT

The following databases (up to March 2017) PubMed, Scopus and Web of Science were used, searching the following key words: γ-hydroxybutyrate, GHB, GHB glucuronide, hair. The main key words "GHB" and "γ-hydroxybutyrate" were searched singularly and then associated individually to each of the other keywords.

SUMMARY

Of the 2304 sources found, only 20 were considered appropriate for the purpose of this paper. Summing up all the studies investigating endogenous GHB concentration in hair, a very broad concentration range from 0 to 12 ng/mg was found. In order to detect a single GHB dose in hair it is necessary to commonly wait 1 month for collecting hair and a segmental analysis of 3 or 5 mm fragments and the calculation of a ratio between the targeted segment and the others represent a reliable method to detect a single GHB intake considering that the ratios presently proposed vary from 3 and 10. The only two studies so far performed, investigating GHB-Glucuronide in hair, show that the latter does not seem to provide any diagnostic information regarding GHB exposure.

OUTLOOK

A practical operative protocol is proposed to be applied in all suspected cases of GHB-facilitated sexual assault (GHB-FSA).

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.

Microbial forensics: new breakthroughs and future prospects

Recent advances in genetic data generation, through massive parallel sequencing (MPS), storage and analysis have fostered significant progresses in microbial forensics (or forensic microbiology). Initial applications in circumstances of biocrime, bioterrorism and epidemiology are now accompanied by the prospect of using microorganisms (i) as ancillary evidence in criminal cases; (ii) to clarify causes of death (e.g., drownings, toxicology, hospital-acquired infections, sudden infant death and shaken baby syndromes); (iii) to assist human identification (skin, hair and body fluid microbiomes); (iv) for geolocation (soil microbiome); and (v) to estimate postmortem interval (thanatomicrobiome and epinecrotic microbial community). When compared with classical microbiological methods, MPS offers a diverse range of advantages and alternative possibilities. However, prior to its implementation in the forensic context, critical efforts concerning the elaboration of standards and guidelines consolidated by the creation of robust and comprehensive reference databases must be undertaken.

Utilisation de l'acide gamma-hydroxybutyrique (ghb) dans les rave-parties et pour la soumission chimique en france : mythe ou réalité?

Since many years gamma-hydroxybutyric acid (GHB) is presented as very popular in rave-parties and for bodybuilders. It seems to be a controversy between media coverage and the results of toxicological analysis done in high-level laboratories. In order to clarify this problem, we compiled the data of 6 laboratories. They used the same analytical method by GC/MS. Depending the laboratory, the limit of detection was 1-2 μg/mL and the limit of quantification was 2.5-5 μg/ mL. Two labs where looking for GHB in each forensic case (100 and 150 cases a year). Others labs performed GHB analysis only on specific request (each 10 cases a year). Mean time between ingestion of GHB and blood/urine sampling was 12-48 h. Mean time between sampling and analysis was much higher (a few hours to a few month. All samples were stored at +4°C. Only 3 cases were considered as positive (blood GHB : 165, 132 and 114 μg/mL, urine GHB : 7450 and 436 μg/ mL) They were admitted in an hospital EU. Interpreting results remains very difficult because GHB is endogenous, present in blood and urine, and its half-life is very short. One has to report only « positive » GHB results when amounts are higher than 5 μg/mL in blood and 10 μg/mL in urine. Obviously, forensic toxicologists have to play a very important part in diagnosis of GHB intoxications and estimating its frequency. Actually, because the lack of data in France, it is not possible to answer the question asked in the title of this paper.

Acute toxicity and withdrawal syndromes related to γ-hydroxybutyrate (GHB) and its analogues γ-butyrolactone (GBL) and 1,4-butanediol (1,4-BD)

Gamma-hydroxybutyrate (GHB) has been used as a recreational drug since the 1990s and over the last few years there has been increasing use of its analogues gamma-butyrolactone (GBL) and to a lesser extent 1,4-butanediol (1,4BD). This review will summarize the literature on the pharmacology of these compounds; the patterns and management of acute toxicity associated with their use; and the clinical patterns of presentation and management of chronic dependency associated with GHB and its analogues.

Collection of biological samples in forensic toxicology

Forensic toxicology is the study and practice of the application of toxicology to the purposes of the law. The relevance of any finding is determined, in the first instance, by the nature and integrity of the specimen(s) submitted for analysis. This means that there are several specific challenges to select and collect specimens for ante-mortem and post-mortem toxicology investigation. Post-mortem specimens may be numerous and can endow some special difficulties compared to clinical specimens, namely those resulting from autolytic and putrefactive changes. Storage stability is also an important issue to be considered during the pre-analytic phase, since its consideration should facilitate the assessment of sample quality and the analytical result obtained from that sample. The knowledge on degradation mechanisms and methods to increase storage stability may enable the forensic toxicologist to circumvent possible difficulties. Therefore, advantages and limitations of specimen preservation procedures are thoroughfully discussed in this review. Presently, harmonized protocols for sampling in suspected intoxications would have obvious utility. In the present article an overview is given on sampling procedures for routinely collected specimens as well as on alternative specimens that may provide additional information on the route and timing of exposure to a specific xenobiotic. Last, but not least, a discussion on possible bias that can influence the interpretation of toxicological results is provided. This comprehensive review article is intented as a significant help for forensic toxicologists to accomplish their frequently overwhelming mission.

Retrospective drug detection in cases of drug-facilitated sexual assault: challenges and perspectives for the forensic toxicologist

Reported incidences of drug-facilitated sexual assault (DFSA) are on the increase worldwide. These cases represent a particular challenge for the forensic toxicologist due to the difficulty in obtaining adequate evidence of drug administration. Primarily, this is due to the nature and diversity of the drugs involved, their pharmacology and sampling timescales. Evaluating whether a drug has been administered to a victim for the purpose of sexual assault can often be difficult, if not impossible. This review draws attention to this burgeoning crime and focuses on the unique challenges DFSA cases present in terms of evidential analysis. Current analytical methodologies for investigating DFSA are highlighted and discussed along with developments in improving analytical procedures. In particular, enlarging detection windows by adopting emerging LC–MS techniques is also discussed. This review also highlights the use of cutting-edge technologies such as ultra-HPLC and the use of alternative matrices for addressing the problem of improved retrospective drug detection.

Simultaneous quantification of nicotine, opioids, cocaine, and metabolites in human fetal postmortem brain by liquid chromatography tandem mass spectrometry

A validated method for simultaneous LCMSMS quantification of nicotine, cocaine, 6-acetylmorphine (6AM), codeine, and metabolites in 100 mg fetal human brain was developed and validated. After homogenization and solid-phase extraction, analytes were resolved on a Hydro-RP analytical column with gradient elution. Empirically determined linearity was from 5-5,000 pg/mg for cocaine and benzoylecgonine (BE), 25-5,000 pg/mg for cotinine, ecgonine methyl ester (EME) and 6AM, 50-5000 pg/mg for trans-3-hydroxycotinine (OH-cotinine) and codeine, and 250-5,000 pg/mg for nicotine. Potential endogenous and exogenous interferences were resolved. Intra- and inter-assay analytical recoveries were > or = 92%, intra- and inter-day and total assay imprecision were < or = 14% RSD and extraction efficiencies were > or = 67.2% with < or = 83% matrix effect. Method applicability was demonstrated with a postmortem fetal brain containing 40 pg/mg cotinine, 65 pg/mg OH-cotinine, 13 pg/mg cocaine, 34 pg/mg EME, and 525 pg/mg BE. This validated method is useful for determination of nicotine, opioid, and cocaine biomarkers in brain.

Forensic chemistry

Forensic chemistry is unique among chemical sciences in that its research, practice, and presentation must meet the needs of both the scientific and the legal communities. As such, forensic chemistry research is applied and derivative by nature and design, and it emphasizes metrology (the science of measurement) and validation. Forensic chemistry has moved away from its analytical roots and is incorporating a broader spectrum of chemical sciences. Existing forensic practices are being revisited as the purview of forensic chemistry extends outward from drug analysis and toxicology into such diverse areas as combustion chemistry, materials science, and pattern evidence.

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.

Analytical pitfalls in hair testing

This review focuses on possible pitfalls in hair testing procedures. Knowledge of such pitfalls is useful when developing and validating methods, since it can be used to avoid wrong results as well as wrong interpretations of correct results. In recent years, remarkable advances in sensitive and specific analytical techniques have enabled the analysis of drugs in alternative biological specimens such as hair. Modern analytical procedures for the determination of drugs in hair specimens - mainly by gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) - are reviewed and critically discussed. Many tables containing information related to this topic are provided.

GC/MS profiling of gamma-hydroxybutyrate and precursors in various animal tissues using automatic solid-phase extraction. Preliminary investigations of its potential interest in postmortem interval determination

To quantify gamma-hydroxybutyrate (GHB) and its physiological metabolites, gamma-aminobutyric acid (GABA), 1,4-butanediol (1,4-BD), and gamma-butyrolactone (GBL) in various animal tissues (kidney, muscle, heart, liver, blood, brain cortex, thalamus, hypothalamus, hippocampus, or pons), an original gas chromatographic/mass spectrometric method with a automated solid-phase extraction by Oasis MCX cartridges on a Gilson Aspec Xli was developed. Using such apparatus allowed the limit of detection (LOD) of target compounds to be significantly lowered (LOD: 0.027, 0.025, and 5.7 microg/mL for GHB, 1,4-BD, and GABA, respectively, in 200 microL or microg of sample). After validation of each analytical step, the satisfactory performances of the apparatus in conjunction with the rapidity and ease of the extraction step make it suitable for simultaneous assay of GHB, 1,4-BD, GBL, and GABA. The method was used to test the correlation between GHB levels in tissues obtained at different times after death of male Sprague-Dawley rats and the postmortem interval. Preliminary results show a linear increase of GHB levels in relation to time of death in thoracic blood and central nervous system of animals kept at 15 and 20 degrees C.

Potential gamma-hydroxybutyric acid (GHB) drug interactions through blood-brain barrier transport inhibition: a pharmacokinetic simulation-based evaluation

Recreational abuse or overdose of gamma-hydroxybutyric acid (GHB) results in dose-dependent central nervous system (CNS) effects including death. As GHB undergoes monocarboxylic acid transporter (MCT)-mediated transport across the blood-brain barrier (BBB), one possible strategy for the management of GHB toxicity/overdose involves inhibition of GHB BBB transport. To test this strategy, interactions between GHB and MCT substrates (salicylic acid or probenecid) were simulated. Competitive, noncompetitive and uncompetitive inhibition mechanisms were incorporated into the GHB-MCT substrate interaction model for inhibitor dosing either pre-, concurrent or post-GHB administration. Simulations suggested that salicylic acid was the better candidate to limit GHB accumulation in the CNS. A time window of effect (> 10% change) was observed for salicylic acid pre- and post-administration, with maximal transport inhibition occurring within 12 hr of pre- and 2 hr of post-administration. Consistent with the prediction that reduced GHB brain concentrations could translate to decreased pharmacodynamic effects, a pilot study in rats showed that the pronounced GHB sedative/hypnotic effects (24.0 +/- 6.51 min; n = 4) in the control group (1.58 mmol/kg GHB plus saline) were significantly (p < 0.05) abrogated by salicylic acid (1.25 mmol/kg) coadministration.

New trends in hair analysis and scientific demands on validation and technical notes

This review focuses on basic aspects of method development and validation of hair testing procedures. Quality assurance is a major issue in drug testing in hair resulting in new recommendations, validation procedures and inter-laboratory comparisons. Furthermore recent trends in research concerning hair analysis are discussed, namely mechanisms of drug incorporation and retention, novel analytical procedures (especially ones using liquid chromatography-mass spectrometry (LC-MS) and alternative sample preparation techniques like solid-phase microextraction (SPME)), the determination of THC-COOH in hair samples, hair testing in drug-facilitated crimes, enantioselective hair testing procedures and the importance of hair analysis in clinical trials. Hair testing in analytical toxicology is still an area in need of further research.

A validated positive chemical ionization GC/MS method for the identification and quantification of amphetamine, opiates, cocaine, and metabolites in human postmortem brain

A sensitive and specific method for the simultaneous detection and quantification of amphetamine, opiates, and cocaine and metabolites in human postmortem brain was developed and validated. Analytes of interest included amphetamine, morphine, codeine, 6-acetylmorphine, cocaine, benzoylecgonine, ecgonine methyl ester, ecgonine ethyl ester, cocaethylene, and anhydroecgonine methyl ester. The method employed ultrasonic homogenization of brain tissue in pH 4.0 sodium acetate buffer and solid phase extraction. Extracts were derivatized with N-methyl-N-(tert-butyldimethylsilyl) trifluoroacetamide and N,O-bis(trimethylsilyl) trifluoroacetamide. Separation and quantification were accomplished on a bench-top positive chemical ionization capillary gas chromatograph/mass spectrometer with selected ion monitoring. Eight deuterated analogs were used as internal standards. Limits of quantification were 50 ng/g of brain. Calibration curves were linear to 1000 ng/g for anhydroecgonine methyl ester and 6-acetylmorphine, and to 2000 ng/g for all other analytes. Accuracy across the linear range of the assay ranged from 90.2 to 112.2%, and precision, as percent relative standard deviation, was less than 16.6%. Quantification of drug concentrations in brain is a useful research tool in neurobiology and in forensic and postmortem toxicology, identifying the type, relative magnitude, and recency of abused drug exposure. This method will be employed to quantify drug concentrations in human postmortem brain in support of basic and clinical research on the physiologic, biochemical, and behavioral effects of drugs in humans.

Feasibility ofD-glucuronate to enhance γ-hydroxybutyric acid metabolism during γ-hydroxybutyric acid toxicity: pharmacokinetic and pharmacodynamic studies

Gamma-Hydroxybutyric acid (GHB) is a drug of abuse. Literature studies showed that D-glucuronate acts as an oxidative stimulator of GHB metabolism following in vivo GHB tracer doses. The present proof-of-concept study investigates if D-glucuronate enhances GHB metabolism and inhibits blood-brain barrier (BBB) carrier-mediated transport of GHB for clinically relevant and toxicological concentrations of GHB. In a randomized cross-over study with a 3 day washout period, rats were intravenously administered GHB (200, 400 or 800 mg/kg) with either saline or D-glucuronate (830 mg/kg i.v. bolus followed by a constant infusion of 1.39 g/kg-h). Systemic and renal GHB pharmacokinetics, as well as onset, offset and duration of GHB sedative/hypnotic effects were measured following each GHB dose. In situ brain perfusion was used to determine if D-glucuronate inhibited GHB BBB transport. D-Glucuronate did not alter GHB sedative/hypnotic effects at all three GHB doses. A model independent approach revealed that GHB systemic (AUC, CL(Total), CL(Metabolism), V(SS), T(1/2)) and renal (CL(Renal), f(e)) pharmacokinetic parameters were unaltered by D-glucuronate administration. GHB influx clearance was unaltered by D-glucuronate suggesting a lack of transport inhibition. These observations suggest that although previously shown to be promising at GHB tracer doses, D-glucuronate lacks therapeutic benefit in the treatment of GHB toxicity.

Urinary endogenous concentrations of GHB and its isomers in healthy humans and diabetics

Urinary endogenous concentrations of gamma-hydroxybutyric acid (GHB), alpha-hydroxybutyric acid (AHB) and beta-hydroxybutyric acid (BHB) have been investigated for both healthy humans and diabetics by using a newly optimized GC-MS procedure. The endogenous concentrations in healthy volunteers' urine ranged 0.16-2.14 microg/ml for GHB, 0.10-2.68 microg/ml for AHB and 8.51-34.7 microg/ml for BHB. In diabetics, the concentrations ranged 0.17-3.03 microg/ml for GHB, 0.14-124 microg/ml for AHB and 4.94-4520 microg/ml for BHB. Although notably elevated BHB and AHB concentrations were observed for severely uncontrolled diabetics, their GHB concentrations ranged within or near the range seen in healthy humans. The results of this study confirm the previously suggested 10 microg/ml cutoff concentration of urinary GHB to distinguish exogenous GHB, even for uncontrolled diabetic patients suffering severe ketoacidosis.

Party drugs: properties, prevalence, patterns, and problems

This review summarizes the latest literature on "party" or "club" drugs, defined as MDMA, GHB, ketamine, and Rohypnol, as published from 2002 to early 2005. Club drugs have been categorized as being used at raves and dance parties. The literature shows that each drug has different properties, users, and settings. Each drug has different adverse effects and requires different acute care protocols. Although these drugs were identified early, scientific information about them, including the toxicological tests to identify them, is still evolving. Increasing numbers of studies on the short- and long-term effects of these drugs on humans are being published, but because of limitations on research using human subjects, they may not always be as rigorous as desired and can be cited by drug users to discredit findings of harm. The lack of research-based information on these drugs has led to the emergence of web sites that may or may not provide accurate data. Evaluated chemical dependency treatment protocols using the latest research for each of these different drugs are needed.

GHB in postmortem toxicology. Discrimination between endogenous production from exposure using multiple specimens

Since gamma-hydroxybutyrate (GHB) is present in both blood and urine of the general population as an endogenous compound, toxicologists must be able to discriminate between these endogenous levels and a concentration resulting from exogenous exposure. The implementation of a cut-off concentration must be done cautiously, due to the wide distribution of endogenous concentrations. To verify the accuracy of a proposed 50 mg/l postmortem blood cut-off, we tested 71 autopsy cases of subjects where the cause of death could exclude GHB exposure. The delay between death and autopsy ranged from 12 to 72 h. GHB was tested by gas chromatography-mass spectrometry (GC-MS) after precipitation. Briefly, 20 microl of blood, bile, or vitreous humor was pipetted in a glass tube, followed by 20 microl of GHB-d6 and 45 microl of acetonitrile. After vortexing and centrifugation, the supernatant was collected and evaporated to dryness. The residue was derivatized with bis(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylchlorosilane (TMCS) for 20 min at 70 degrees C. After injection on a 30 m HP5 MS capillary column, GHB (m/z 233, 204, and 147) and GHB-d6 (m/z 239) were identified by MS. GHB tested positive in all the 71 whole blood (cardiac) specimens, with concentrations in the range 0.4-409 mg/l, with a major distribution in the range 10-40 mg/l. A concentration >50 mg/l was observed in 14 cases. As there was no data to support GHB exposure, this was considered as postmortem formation. In order to discriminate this contamination, when available, femoral blood, bile or/and, vitreous humor were tested. The following results were obtained: cardiac blood (55-409 mg/l) versus bile (6.1-238 mg/l) in seven cases; cardiac blood (51-409 mg/l) versus femoral blood (17-44 mg/l) in five cases, and cardiac blood (51-409 mg/l) versus vitreous humor (3.9-2 mg/l) in six cases. It is obvious that bile does not fit the requirements for discrimination and that femoral blood and mostly vitreous humor can be of particular interest. These results demonstrate that a positive (>50 mg/l) postmortem blood GHB concentration cannot support alone drug exposure and that it is essential to document the case with other specimens, including peripheral blood and vitreous humor.

Acute toxic effects of club drugs

This article summarizes the short-term physiological toxicity and the adverse behavioral effects of four substances (GHB, ketamine, MDMA, and Rohypnol) that have been used at latenight dance clubs. The two primary data sources were case studies of human fatalities and experimental studies with laboratory animals. A safety ratio was calculated for each substance based on its estimated lethal dose and its customary recreational dose. GHB (gamma-hydroxybutyrate) appears to be the most physiologically toxic; Rohypnol (flunitrazepam) appears to be the least physiologically toxic. The single most risk-producing behavior of club drug users is combining psychoactive substances, usually involving alcohol. Hazardous drug-use sequelae such as accidents, aggressive behavior, and addiction were not factored into the safety ratio estimates.

Postmortem toxicology of drugs of abuse

Conducting toxicology on post-mortem specimens provides a number of very significant challenges to the scientist. The range of additional specimens include tissues such as decomposing blood and other tissues, hair, muscle, fat, lung, and even larvae feeding on the host require special techniques to isolate a foreign substance and allow detection without interference from the matrix. A number of drugs of abuse are unstable in the post-mortem environment that requires careful consideration when trying to interpret their significance. Heroin, morphine glucuronides, cocaine and the benzodiazepines are particularly prone to degradation. Moreover, redistributive process can significantly alter the concentration of drugs, particularly those with a higher tissue concentration than the surrounding blood. The designer amphetamines, methadone and other potent opioids will increase their concentration in blood post-mortem. These processes together with the development of tolerance means that no concentration of a drug of abuse can be interpreted in isolation without a thorough examination of the relevant circumstances and after the conduct of a post-mortem to eliminate or corroborate relevant factors that could impact on the drug concentration and the possible effect of a substance on the body. This article reviews particular toxicological issues associated with the more common drugs of abuse such as the amphetamines, cannabinoids, cocaine, opioids and the benzodiazepines.

Comparison of acute lethal toxicity of commonly abused psychoactive substances

AIMS

To determine the acute lethal toxicity of a range of psychoactive substances in terms of the dose customarily used as a single substance for non-medical purposes.

DESIGN AND METHOD

A structured English-language literature search was conducted to identify experimental studies and clinical reports that documented human and non-human lethal doses of 20 abused substances that are distributed widely in Europe and North America. Four inclusion criteria were specified for the reports, and approximately 3000 relevant records were retrieved from search engines at Biosis, Science Citation Index, Google and the National Library of Medicine's Gateway. In order to account for different drug potencies, a 'safety ratio' was computed for each substance by comparing its reported acute lethal dose with the dose most commonly used for non-medical purposes.

FINDINGS

The majority of published reports of acute lethal toxicity indicate that the decedent used a co-intoxicant (most often alcohol). The calculated safety ratios varied between substances by more than a factor of 100. Intravenous heroin appeared to have the greatest direct physiological toxicity; several hallucinogens appeared to have the least direct physiological toxicity.

CONCLUSIONS

Despite residual uncertainties, the substantial difference in safety ratios suggests that abused substances can be rank-ordered on the basis of their potential acute lethality.

Determination of γ-hydroxybutyric acid in biological fluids by using capillary electrophoresis with indirect detection

gamma-Hydroxybutyric acid (GHB) is a central nervous system (CNS) depressant and hypnotic which, in recent times, has shown an increasing abuse either as recreational drug (due to its euphoric effects and ability to reduce inhibitions) or as doping agent (enhancer of muscle growth). Analogues of GHB, namely gamma-butyrolactone (GBL) and 1,4-butanediol (1,4-BD), share its biological activity and are rapidly converted in vivo into GHB. At present, GHB and analogues are placed in the Schedules of Controlled Substances. Numerous intoxications in GHB abusers have been reported with depressive effects, seizures, coma and possibly death. The purpose of the present work was the development of a rapid analytical method based on capillary zone electrophoresis for the direct determination of GHB in human urine and serum at potentially toxic concentrations. Analytical conditions were as follows. Capillary: length 40 cm (to detector), 75 microm i.d.; buffer: 5.0 mM Na(2)HPO(4), 15 mM sodium barbital adjusted to pH 12 with 1.0 M NaOH; voltage: 25 kV at 23 degrees C; indirect UV detection at 214 nm; injection by application of 0.5 psi for 5 s. alpha-Hydroxyisobutyric acid was used as internal standard (IS). Sample pretreatment was limited to 1:8 dilution. Under these conditions, the sensitivity was approximately 3.0 microg/ml (signal-to-noise ratio >3). Calibration curves prepared in water, urine and serum were linear over concentration ranges 25-500 microg/ml with R(2)>/=0.998. Analytical precision was fairly good with R.S.D.<0.60% (including intraday and day-to-day tests). Quantitative precision in both intraday and day-to-day experiments was also very satisfactory with R.S.D.</=4.0%. No interferences were found neither from the most common "drugs of abuse" nor from endogenous compounds. In conclusion, capillary electrophoresis can offer a rapid, precise and accurate method for GHB determination of biological fluids, which could be important for screening purposes in clinical and forensic toxicology.

??-Hydroxybutyrate

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

Toxicology in the critically ill patient

Intoxications present in many forms including: known drug overdose or toxic exposure, illicit drug use, suicide attempt, accidental exposure, and chemical or biological terrorism. A high index of suspicion and familiarity with toxidromes can lead to early diagnosis and intervention in critically ill, poisoned patients. Despite a paucity of evidence-based information on the management of intoxicated patients, a rational and systematic approach can be life saving.

Post-mortem toxicology: what the dead can and cannot tell us

The evaluation of postmortem laboratory assays of drugs needs to be performed in a systematic manner. The condition of the body, drug characteristics, matrix and site analysis are factors which need to be considered in the proper interpretation of an autopsy specimen result.