Gamma hydroxybutyric acid (GHB) concentrations in humans and factors affecting endogenous production

Knock-out drugs: their prevalence, modes of action, and means of detection

BACKGROUND

Knock-out drugs are used to facilitate the commission of a crime, generally either robbery or sexual assault. Although media reports on the use of knock-out drugs have become more frequent, there are no robust epidemiological data on the incidence of drug-facilitated robbery or sexual assault, presumably because many crimes of these types do not enter into official statistics.

METHODS

The authors describe the modes of action and toxicological means of detection of the substances most frequently used as knock-out drugs on the basis of a selective literature research on the terms "drug-facilitated sexual assaults" (DFSA) and "drug-facilitated crimes" (DFC).

RESULTS

The most frequently used drug in cases of sexual assault is still alcohol (ca. 40% to 60%), followed by illegal drugs (cannabis, cocaine). The presence of involuntarily consumed medications and drugs of abuse is demonstrated by routine toxicological analysis only in relatively few cases (ca. 2%). The substances most commonly found are benzodiazepines, followed by other hypnotics. In Europe, the illegal substance gamma-hydroxybutyric acid (GHB, "Liquid Ecstasy"), often mentioned as a "date-rape drug," is only rarely detected with sufficient medicolegal certainty. This may be due to its rapid elimination (it is detectable in blood for up to 8 hours, in urine for up to 12 hours) as well as its physiological occurrence in the body. If the toxicological analysis of blood and urine is negative in a case of suspected DFSA, then the analysis of a hair sample about four weeks after the assault can detect the presence of drugs consumed at that time. If the victim has long hair, it may be possible to detect knock-out drugs taken more than four weeks earlier. In Europe, convictions for drug-facilitated crimes are comparatively rare, mainly because of the difficulty of demonstrating conclusive evidence.

CONCLUSIONS

A careful medical history and physical examination and the careful taking of biological samples for toxicological analysis form the basis for the detection of drug-facilitated crimes.

Should ethanol be scheduled as a drug of high risk to public health?

Six criteria described in the New Zealand Misuse of Drugs Act and used by the Expert Advisory Committee on Drugs (EACD) for determining the risk of a drug to public health were examined in relation to ethanol, using gamma-hydroxybutyric acid (GHB) as a comparator drug. GHB is an ideal candidate for use as a comparator because it is a sedative substance very similar to ethanol and has been previously investigated by the EACD using these six criteria. GHB was subsequently classified as a Class B1 drug under the Misuse of Drugs Act, that is, as a prohibited drug of high risk to public health. The dangerousness level of ethanol was found to be at least similar to that of GHB in this analysis. This highlights a major discrepancy in public policy.

Chemical submission: results of 4-year French inquiry

Psychoactive substances may be administered without the knowledge of a victim in order to induce incapacitation and thus facilitate criminal actions. The characteristics of the victims and the drugs used in such suspected chemical submissions (CS) were analyzed in 309 cases collected from October 2003 to December 2007 through a national survey. Out of 309 cases, 158 met all criteria of CS. The victims were mostly female (n = 89, 56%). The type of aggression was mostly sexual assault (in 79 cases 50%). Benzodiazepines and related drugs were detected in 129 victims (82%) and were mostly clonazepam, zolpidem, and bromazepam whereas flunitrazepam and gamma hydroxybutyrate, well known for their use in CS, were identified in 11 (7%) and five (3%) of the 158 victims. CS is not an anecdotal phenomenon in France. Information for health professionals and workers in forensic structures as well as education of the general population associated with preventive measures such as drug dosage form changes should contribute to improved care management of victims and decreased risk.

GHB urine concentrations after single-dose administration in humans

Gamma-hydroxybutyric acid (GHB) is used as an illicit drug and is implicated in drug-facilitated sexual assault, but it also has some therapeutic uses. Detection of GHB in urine is important for forensic testing and could be of clinical benefit in overdose management. Urine GHB concentration-time profiles have not been well-characterized or correlated with doses used therapeutically. GHB levels were measured by gas chromatography-mass spectrometry in urine collected over 24 h from 16 adults administered single doses of 50 mg/kg GHB (Xyrem) alone and combined with 0.6 g/kg ethanol. Peak GHB urine concentrations averaged 150-200 mg/L and occurred in the 0-3 h urine collection. Significant variability in GHB urine levels between individuals was observed. Caucasians had lower urine concentrations than other races/ethnicities (p = 0.03). Men had lower GHB levels than women in the first 3 h after dosing (p = 0.038). Coingestion of ethanol did not significantly affect renal clearance of GHB, but urine GHB concentrations were lower in the first 3 h when ethanol and GHB were coingested (p = 0.039). At a proposed cut-off of 10 mg/L to distinguish endogenous versus exogenous GHB levels, 12.5% of the samples collected from 3 to 6 h, 81.3% of samples collected from 6 to 12 h, and 100% of urine specimens collected from 12 to 24 h were below this level. We conclude that the detection time for GHB in urine may be shorter than the previously reported 12-h window in some people taking therapeutic doses of GHB.

Further evidence of in vitro production of gamma-hydroxybutyrate (GHB) in urine samples

This study was designed to supplement previous studies that documented in vitro production of gamma-hydroxybutyrate (GHB) in urine samples. Urine samples were provided by subjects who reported that they had never used GHB (n=31). The specimens were stored under standard conditions of refrigeration (5 degrees C) without any preservatives added. All specimens were repeatedly analyzed for the presence of endogenous GHB over a 6-month period using a previously reported headspace GC-MS method. Significant elevations in GHB were observed in many of the urine samples as storage time increased. As a result, the in vitro production of GHB may increase the apparent GHB concentrations in urine during storage. This potential for an artificial increase in GHB concentration must be appreciated when establishing the threshold between endogenous and exogenous concentrations of GHB.

Disposition of Gamma-Hydroxybutyric Acid in Conventional and Nonconventional Biologic Fluids After Single Drug Administration: Issues in Methodology and Drug Monitoring

Little controlled drug administration data are available to aid in the interpretation of gamma-hydroxybutyric acid (GHB) distribution in conventional and nonconventional fluids and the potential correlation between the pharmacokinetics of GHB and drug effects. Single oral sodium GHB doses of 50 mg/kg were administered to five volunteers. Plasma, oral fluid, urine, and sweat were analyzed for GHB by gas chromatography-mass spectrometry. GHB stability in plasma was studied at different storage temperatures. Subjective effects were measured using a set of 13 different visual analog scales. Mean peak GHB plasma concentrations at 30 minutes were 83.1 microg/mL. After the absorption phase, concentrations declined to mean values of 0.9 microg/mL at 6 hours. GHB was found in oral fluid at peak value concentrations equivalent to one third to one fourth of those found in plasma. The oral fluid-to-plasma ratio varied two fold in the 1- to 6-hour time range but always was lower than unit. The mean half-life (t1/2) of GHB was approximately 0.7 hour in plasma and approximately 1.2 hours in oral fluid. GHB urinary excretion is less than 2% of the dose administered. GHB was also detected in sweat at low concentrations. GHB showed a mixed sedative-stimulant pattern with subjective effects peaking between 1 and 1.5 hours after drug administration and lasting for 2 hours. Oral fluid and sweat appeared not to be suitable biologic matrices for monitoring GHB consumption. GHB-mediated subjective effects are related to GHB plasma concentrations.

Carbon isotopic ratio analysis by gas chromatography/combustion/isotope ratio mass spectrometry for the detection of gamma-hydroxybutyric acid (GHB) administration to humans

Since GHB (gamma-hydroxybutyric acid) is naturally produced in the human body, clinical and forensic toxicologists must be able to discriminate between endogenous levels and a concentration resulting from exposure. To suggest an alternative to the use of interpretative concentration cut-offs, the detection of exogenous GHB in urine specimens was investigated by means of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). GHB was isolated from urinary matrix by successive purification on Oasis MCX and Bond Elute SAX solid-phase extraction (SPE) cartridges prior to high-performance liquid chromatography (HPLC) fractioning using an Atlantis dC18 column eluted with a mixture of formic acid and methanol. Subsequent intramolecular esterification of GHB leading to the formation of gamma-butyrolactone (GBL) was carried out to avoid introduction of additional carbon atoms for carbon isotopic ratio analysis. A precision of 0.3 per thousand was determined using this IRMS method for samples at GHB concentrations of 10 mg/L. The (13)C/(12)C ratios of GHB in samples of subjects exposed to the drug ranged from -32.1 to -42.1 per thousand, whereas the results obtained for samples containing GHB of endogenous origin at concentration levels less than 10 mg/L were in the range -23.5 to -27.0 per thousand. Therefore, these preliminary results show that a possible discrimination between endogenous and exogenous GHB can be made using carbon isotopic ratio analyses.

Gamma-hydroxybutyrate and ethanol effects and interactions in humans

BACKGROUND

Gamma-hydroxybutyrate (GHB) is a common drug of abuse that can produce serious toxicity, particularly when used with other sedatives. We examined the individual and combined effects of GHB and ethanol in human volunteers.

METHODS

Sixteen healthy adults (7 men) were given 50 mg/kg GHB (Xyrem), 0.6 g/kg ethanol in 2 doses, alone and combined in a double-blind, placebo-controlled, crossover study. Plasma concentrations, heart rate (HR), blood pressure (BP), and oxygen saturation (O2sat) were serially monitored for 24 hours.

RESULTS

Adverse events included 2 instances of hypotension and 6 episodes of vomiting with GHB-plus-ethanol ingestion. Oxygen saturation was decreased by GHB and ethanol individually, and maximally decreased by the drugs combined (max -2.1% +/- 0.3%, P < 0.0001 vs placebo). Compared with baseline, systolic and diastolic BP were significantly decreased, and HR was increased by ethanol but not affected by GHB alone (maximum systolic BP change -15.7 +/- 3.0 mm Hg, P = 0.0006; maximum HR change 13.5 +/- 2.3 beats per minute, P = 0.006). Ethanol coingestion resulted in 16% higher GHB maximal plasma concentration and 29% longer elimination half-life, indicating possible enhanced bioavailability or reduced clearance of GHB caused by ethanol, however, these effects were not statistically significant.

CONCLUSIONS

Modest doses of GHB do not affect hemodynamic function, but O2sat was decreased. Gamma-hydroxybutyrate-plus-ethanol resulted in more adverse effects, including gastrointestinal disturbances, hypotension, and decreased O2sat, but only minimal pharmacokinetic interactions were observed.

Gamma-hydroxybutyric acid stability and formation in blood and urine

Gamma-hydroxybutyric acid (GHB) can cause problems in interpretation of toxicological findings due to its endogenous nature, significant production in tissues after death and potential formation in stored samples. Our study was designed to determine the influence of storage conditions on GHB levels and its possible in vitro formation in blood and urine in cases where no exogenous use of GHB or its precursors was suspected. The samples were prepared by validated method based on liquid-liquid reextraction with adipic acid internal standard and MSTFA derivatization and assayed on a GC-MS operating in EI SIM mode. The first part of the study was performed with pooled blood and urine samples obtained from living and deceased subjects stored with and without NaF (1% w/v) at 4 and -20 degrees C over 8 months. In ante-mortem samples (both blood and urine) no significant GHB production was found. After 4 months of storage, the substantial GHB rise up to 100 mg/Lwas observed in post-mortem blood stored at 4 degrees C without NaF with subsequent gradual decrease in following months. The inhibition of GHB production was apparent during storage in NaF treated frozen blood samples. In post-mortem urine only slight temporary GHB levels were ascertained (up to 8 mg/L). The second part of our study was aimed to analyse 20 individual post-mortem blood samples stored at 4 degrees C for 16-27 days between autopsy and analysis without preservation followed by storage at 4 degrees C with NaF for 4 months. The temporary GHB production with maximum of 28 mg/Lwas detected in some samples.

-Hydroxybutyrate (GHB) in Humans: Pharmacodynamics and Pharmacokinetics

Despite gamma-hydroxybutyrate (GHB) therapeutic uses and the increasing concern about its toxicity, few studies have addressed GHB dose-related effects under controlled administration and their relationship with its pharmacokinetics. The study design was double-blind, randomized, crossover, and controlled. As a pilot pharmacology phase I study, increasing doses of GHB were given. Single oral sodium GHB doses (40, 50, 60, and 72 mg/kg) were administered to eight volunteers. Plasma and urine were analyzed for GHB by gas chromatography-mass spectrometry. Physiological effects, psychomotor performance, and subjective effects were examined simultaneously. GHB produced dose-related changes in subjective effects as measured by questionnaires and VAS. GHB showed a mixed stimulant-sedative pattern, with initially increased scores in subjective feeling of euphoria, high, and liking followed by mild-moderate symptoms of sedation with impairment of performance and balance. Mean peak GHB plasma concentrations were 79.1, 83.1, 113.5, and 130.1 mug/L for 40, 50, 60, and 72 mg/kg, respectively. GHB-mediated physiological and subjective effects were dose dependent and related to GHB plasma concentrations. GHB urinary excretion was mainly related to administered doses. GHB-mediated subjective and physiological effects seem dose dependent and related to GHB plasma concentrations. Results suggest a high abuse liability of GHB in the range of dose usually consumed.

Effects of drinking and smoking on endogenous levels of urinary γ-hydroxybutyric acid, a preliminary study

The aim of this study was to determine if the endogenous levels of gamma-hydroxybutyric acid (GHB) in urine were affected by drinking and smoking. Urine samples were obtained from 20 healthy volunteers (15 males, 21-45 years; 5 females, 22-24 years). This population included four average drinkers (males), 4 average smokers (males), and 12 nonsmokers/nondrinkers (seven males and five females). Urinary levels of GHB were measured by gas chromatography. No gender differences were observed in the urinary levels of endogenous GHB. The urinary levels of GHB in males were 0.52+/-0.37 microg/ml in smokers, 0.28+/-0.21 microg/ml in nonsmokers/nondrinkers, and 0.23+/-0.04 microg/ml in drinkers. Urinary GHB levels were measured three times a day for 5 consecutive days in a male from each group. Large intra-individual differences were observed over the 5-day period in a smoker and a nonsmoker/nondrinker. No significant changes in daily endogenous GHB levels were observed in a drinker during the period. Our preliminary results suggest that stimulatory effects of nicotine on the central nervous system (CNS) may result in an increase in nocturnal formation of GHB and the depressive effects of ethanol on the CNS may not affect, even may inhibit, nocturnal production of GHB.

Toxicological findings in cases of alleged drug-facilitated sexual assault in the United Kingdom over a 3-year period

This paper outlines the toxicology results from 1014 cases of claimed drug-facilitated sexual assault (DFSA) analysed at the Forensic Science Service, London Laboratory between January 2000 and December 2002. Where appropriate, either a whole blood sample and/or a urine sample was analysed for alcohol, common drugs of abuse and potentially stupefying drugs. The results were interpreted with respect to the number of drugs detected and an attempt was made to distinguish between voluntary and involuntary ingestion from information supplied. Alcohol (either alone or with an illicit and/or medicinal drug) was detected in 470 of all cases (46%). Illicit drugs were detected in 344 cases (34%), with cannabis being the most commonly detected (26% of cases), followed by cocaine (11%). In 21 cases (2%), a sedative or disinhibiting drug was detected which had not been admitted and could therefore be an instance of deliberate spiking. This included three cases in which complainants were allegedly given Ecstasy (MDMA) without their knowledge. Other drugs detected included gammahydroxybutyrate (GHB) and the benzodiazepine drugs diazepam and temazepam. Another nine cases (1%) involved the complainant being either given or forced to ingest pharmaceutical tablets or an illicit drug.

Chemosynthesis of bioresorbable poly(γ-butyrolactone) by ring-opening polymerisation: a review

Recent advances in the synthesis of poly(gamma-butyrolactone) have yielded homopolymers of up to 50,000 Mw from the low-cost monomer gamma-butyrolactone. This monomer has for the better part of a century been thought impossible to polymerise. Poly(gamma-butyrolactone) displays properties that are ideal for tissue-engineering applications and the bacterially derived equivalent, poly(4-hydroxybutyrate) (P4HB), has been evaluated for such uses. The glass transition temperature (-48 to -51 degrees C), melting point (53-60 degrees C), tensile strength (50 MPa), Young's modulus (70 MPa) and elongation at break (1000%) of P4HB make it a very useful biomaterial. Poly(gamma-butyrolactone) degrades to give gamma-hydroxybutyric acid which is a naturally occurring metabolite in the body and it has been shown to be bioresorbable. Investigation into the synthesis of poly(gamma-butyrolactone) has recently produced homo-oligomeric diols 400-1000 Mw that are suitable for reacting with diisocyanates to form polyurethanes. Biodegradable polyurethanes made from diols of polyglycolide (PGA) and poly(epsilon-caprolactone) (PCL) have the disadvantage of high glass transition and slow degradation, respectively. Poly(gamma-butyrolactone) can be thought of as being the missing link in the biodegradable polyester family immediately between PGA and PCL and displaying intermediate properties.

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.

Site-dependent production of γ-hydroxybutyric acid in the early postmortem period

This study compared endogenous gamma-hydroxybutyric acid (GHB) concentrations in various postmortem fluid samples of 25 autopsy cases. All bodies were stored between 10-20 degrees C until autopsy, and the intervals between death and autopsy were less than 2 days (6-48 h). GHB concentrations were measured by headspace gas chromatography after GHB was converted to gamma-butyrolactone. Endogenous GHB concentrations were significantly higher in femoral venous blood (4.6+/-3.4 microg/ml, n=23) than in cerebrospinal fluid (1.8+/-1.5 microg/ml, n=9), vitreous humor (0.9+/-1.7 microg/ml, n=8), bile (1.0+/-1.1 microg/ml, n=9) and urine (0.6+/-1.2 microg/ml, n=12). GHB concentrations were similar in blood samples taken from different sites. Cut-off limits of 30 and 10 microg/ml are proposed for blood and urine, respectively, to discriminate between exogenous and endogenous GHB in decedents showing no or little putrefaction (postmortem intervals usually 48 h or less). The criterion established for endogenous GHB in postmortem urine may also be applicable to analytical results in cerebrospinal fluid, vitreous humor and bile from deceased persons.

Gamma-hydroxybutyric acid: neurobiology and toxicology of a recreational drug

gamma-Hydroxybutyric acid (GHB) is a short-chain fatty acid that occurs naturally in mammalian brain where it is derived metabolically from gamma-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the brain. GHB was synthesised over 40 years ago and its presence in the brain and a number of aspects of its biological, pharmacological and toxicological properties have been elucidated over the last 20-30 years. However, widespread interest in this compound has arisen only in the past 5-10 years, primarily as a result of the emergence of GHB as a major recreational drug and public health problem in the US. There is considerable evidence that GHB may be a neuromodulator in the brain. GHB has multiple neuronal mechanisms including activation of both the gamma-aminobutyric acid type B (GABA(B)) receptor, and a separate GHB-specific receptor. This complex GHB-GABA(B) receptor interaction is probably responsible for the protean pharmacological, electroencephalographic, behavioural and toxicological effects of GHB, as well as the perturbations of learning and memory associated with supra-physiological concentrations of GHB in the brain that result from the exogenous administration of this drug in the clinical context of GHB abuse, addiction and withdrawal. Investigation of the inborn error of metabolism succinic semialdehyde deficiency (SSADH) and the murine model of this disorder (SSADH knockout mice), in which GHB plays a major role, may help dissect out GHB- and GABA(B) receptor-mediated mechanisms. In particular, the mechanisms that are operative in the molecular pathogenesis of GHB addiction and withdrawal as well as the absence seizures observed in the GHB-treated animals.

Nonfatal instances of intoxication with gamma-hydroxybutyrate in the United Kingdom

There has been much publicity regarding the use and abuse of gamma-hydroxybutyrate (GHB, "liquid ecstasy," or "GBH"). GHB has been found to be an endogenous compound but has also been used for various therapeutic applications in addition to illicit use, particularly as a dietary supplement, sexual adjunct, and "party drug." Toxicological analysis was performed using urine and/or plasma specimens from 27 nonfatal instances of suspected GHB intoxication in the United Kingdom between May 1998 and May 2003. GHB was detected in the plasma and urine, invariably with the additional presence of ethanol and other drugs of abuse (eg, amphetamines, cocaine, and morphine). GBL was also detected in the majority of urine specimens analyzed but was not detected in the plasma samples (<10 mg/L). The mean plasma and urine concentrations measured as "total GBL" were found to be 245 mg/L (range 86-551 mg/L) and 1732 mg/L (range 5-5581 mg/L), respectively. This is believed to be the largest compilation of nonfatal cases from the United Kingdom.

Simultaneous analysis of gamma-hydroxybutyric acid and its precursors in urine using liquid chromatography–tandem mass spectrometry

We have developed a rapid method that enables the simultaneous analysis of gamma-hydroxybutyrate (GHB) and its precursors, i.e. gamma-butyrolactone (GBL) and 1,4-butanediol (1,4-BD) in urine. The method comprised a simple dilution of the urine sample, followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Chromatographic separation was achieved using an Atlantis dC18 column, eluted with a mixture of formic acid and methanol. The method was linear from 1-80 mg/L for GHB and 1,4-BD and from 1-50 mg/L for GBL. The limit of quantification was 1 mg/L for all analytes. The procedure, which has a total analysis time (including sample preparation) of less than 12 min, was fully validated and applied to the analysis of 182 authentic urine samples; the results were correlated with a previously published GC-MS procedure and revealed a low prevalence of GHB-positive samples. Since no commercial immunoassay is available for the routine screening of GHB, this simple and rapid method should prove useful to meet the current increased demand for the measurement of GHB and its precursors.

The possible influence of micro-organisms and putrefaction in the production of GHB in post-mortem biological fluid

In recent years, the post-mortem production of the drug of abuse gamma-hydroxybutyric acid (GHB) in biological fluids (e.g. blood and urine) has caused various interpretative problems for toxicologists. Previously, other researchers have shown certain microbial species (Pseudomonas spp. and Clostridium aminobutyricum) possess the necessary enzymes to convert GABA to GHB. A preliminary investigation involving putrefied post-mortem blood indicated there was no observed relationship between "endogenous" GHB concentrations and concentrations of common putrefactive markers (tryptamine and phenyl-2-ethylamine). Microbiological analysis identified the presence of various micro-organisms: Clostridia spp., Escherichia coli, Proteus vulgaris, Enterococcus faecalis and Aeromonoas spp. Equine plasma, human blood and urine samples were inoculated with these and an additional micro-organism (Pseudomonas aeruginosa) and incubated at 22 degrees C for 1 month. Following comparison with control samples and pre-inoculation concentrations, the data indicated an apparent production of GHB in unpreserved P. aeruginosa inoculated blood (2.3 mg/l). All other fluoride-preserved and unpreserved samples (including controls) had GHB concentrations <1mg/l. Although this concentration is lower than is typically associated with "endogenous" post-mortem GHB concentrations, this paper proposes a potential microbial production of GHB with time.

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.