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

The interest of using vitreous humor for γ-hydroxybutyrate (GHB) quantification in related fatalities: Stability evaluation, case report and literature review

Analysis and interpretation of the findings for γ-hydroxybutyrate (GHB) in related fatalities remains problematic. Indeed, GHB is a naturally occurring compound present in both the mammalian central nervous system and peripheral tissue. Moreover, a postmortem increase in endogenous GHB concentration has been observed, especially in blood. Facing this issue, the use of an alternative matrix such as vitreous humor (VH) can thus be particularly interesting for GHB testing and quantification. VH is considered to be less prone to postmortem redistribution, is easy to collect, and has relatively few interfering compounds for the analytical process. In this context, the authors report the case of a GHB-related fatality involving 22-year-old male. In this case, GHB femoral blood (FB) (790 mg/L) and vitreous (750 mg/L) concentrations appeared similar with a FB to VH (FB/VH) ratio of 1.05. In addition, other similar cases with both GHB blood and vitreous concentrations were reviewed. Five cases were identified. The blood to VH ratios ranging from 0.13 to 2.58. Finally, GHB stability was documented in postmortem blood and VH, in order to address the reliability of VH as an alternative matrix for GHB quantitation at postmortem. GHB appeared relatively stable in postmortem blood specimens (at 50 mg/L) over a period of 28 days when stored at +4 °C or -20 °C. The same results were observed in VH specimens.

Gamma-hydroxybutyrate (GHB), 1,4-butanediol (1,4BD), and gamma-butyrolactone (GBL) intoxication: A state-of-the-art review

γ-hydroxybutyrate (GHB) is synthesized endogenously from γ-aminobutyric acid (GABA) or exogenously from 1,4-butanediol (butane-1,4-diol; 1,4-BD) or γ-butyrolactone (GBL). GBL, and 1,4-BD are rapidly converted to GHB. The gastric absorption time, volume of distribution, and half-life of GHB are between 5 and 45 min, 0.49 ± 0.9 L/kg, and between 20 and 60 min, respectively. GHB and its analogues have a dose-dependent effect on the activation of GHB receptor, GABA-B, and GABA localized to the central nervous system. After ingestion, most patients present transient neurological disorders (lethal dose: 60 mg/kg). Chronic GHB consumption is associated with disorders of use and a withdrawal syndrome when the consumption is discontinued. GHB, GBL, and 1,4-BD are classified as narcotics but only the use of GHB is controlled internationally. They are used for drug facilitated (sexual) assault, recreational purposes, slamsex, and chemsex. To confirm an exogenous intake or administration of GHB, GBL, or 1-4-BD, the pre-analytical conservation is crucial. The antemortem cutoff doses for detection are 5 and 5-15 mg/L, with detection windows of 6 and 10 h in the blood and urine, respectively Control of GHB is essential to limit the number of users, abuse, associated risks, and death related to their consumption.

Complications in post-mortem GHB cut-off values in urine samples: A case report

Gamma-hydroxybutyric acid (GHB) is a drug of abuse, that interplays with a GABAergic system, resulting in an euphoric state and increased mood and impulses. Two cases of fatal mixed intoxications including GHB intake are presented here. In both cases, GHB was used together with multiple other drugs. Interpretation of GHB cut-off values are complicated in post-mortem analysis, because GHB can be post-mortem formed. The post-mortem GHB formation is dependent of the post-mortem interval (PMI) and the storage conditions of the samples. The GHB concentrations in urine are more stable compared to blood samples, when the samples are stored at the correct way at - 20 °C. Therefore, urine is the recommended matrix to analyze in toxicological screenings, since it allows more specific determination of exposure to exogenous GHB. Different cut-off values are used for matrices from living and deceased people. A cut-off value of 30 mg/L is recommended to discriminate between endogenous concentrations and concentrations resulting from exogenous GHB exposure. Moreover, post-mortem GHB formation can take place before sampling. However, when the samples are immediately stored at cooled conditions, no in vitro formation of GHB will take place. Urinary screening of GHB may serve as an initial screening for estimation of exposure of GHB in the body. However, additional quantitative GHB analysis in blood is required to estimate GHB exposure at the time of death. Furthermore, to obtain more reliable results for the ante-mortem GHB exposure, it may be useful to measure other biomarkers, like some GHB metabolites, especially in blood.

Cerebrospinal fluid in forensic toxicology: Current status and future perspectives

In forensic toxicology, alternative biological materials are very useful and important, e.g. in the case of lack of basic body fluids. One alternative biological material is cerebrospinal fluid (CSF). The procedures of the collection of biological material during the autopsy are performed in accordance with local, usually national recommendations, which most often require updating. It is very difficult to assess the possibility of using CSF as an alternative biological material for toxicological studies for the presence of drugs, intoxicants, including new psychoactive substances (commonly known as designer drugs), psychotropic substances, and ethyl alcohol, based on current data. Previous research suggests that CSF may be useful in toxicological studies, but these aspects need to be investigated more carefully because studies have collected CSF from different sites and often the results of different authors are not comparable. It would be necessary to prepare guidelines, e.g. the site of CSF collection that may influence the results of quantitative analysis. It would also be necessary to replicate some studies with a different collection site or a more recent analytical technique, e.g. for comparative testing of blood ethanol and cerebrospinal fluid. Cerebrospinal fluid can be a valuable information carrier in the absence of classic biological material from an autopsy. Investigating these aspects in more detail could allow the future use of this alternative material for routine toxicology analyzes in a forensic laboratory.

Comparison of N-methyl-2-pyrrolidone (NMP) and the "date rape" drug GHB: behavioral toxicology in the mouse model

N-methyl-2-pyrrolidone (NMP) and γ-hydroxybutyrate acid (GHB) are synthetic solvents detected in the recreational drug market. GHB has sedative/hypnotic properties and is used for criminal purposes to compromise reaction ability and commit drug-facilitated sexual assaults and other crimes. NMP is a strong solubilizing solvent that has been used alone or mixed with GHB in case of abuse and robberies. The aim of this experimental study is to compare the acute pharmaco-toxicological effects of NMP and GHB on neurological signs (myoclonia, convulsions), sensorimotor (visual, acoustic, and overall tactile) responses, righting reflex, thermoregulation, and motor activity (bar, drag, and accelerod test) in CD-1 male mice. Moreover, since cardiorespiratory depression is one of the main adverse effects related to GHB intake, we investigated the effect of NMP and GHB on cardiorespiratory changes (heart rate, breath rate, oxygen saturation, and pulse distension) in mice. The present study demonstrates that NMP inhibited sensorimotor and motor responses and induced cardiorespiratory depression, with a lower potency and efficacy compared to GHB. These results suggest that NMP can hardly be used alone as a substance to perpetrate sexual assault or robberies.

Metabolic Profiling and Quantitative Analysis of Cerebrospinal Fluid Using Gas Chromatography-Mass Spectrometry: Current Methods and Future Perspectives

Cerebrospinal fluid is a key biological fluid for the investigation of new potential biomarkers of central nervous system diseases. Gas chromatography coupled to mass-selective detectors can be used for this investigation at the stages of metabolic profiling and method development. Different sample preparation conditions, including extraction and derivatization, can be applied for the analysis of the most of low-molecular-weight compounds of the cerebrospinal fluid, including metabolites of tryptophan, arachidonic acid, glucose; amino, polyunsaturated fatty and other organic acids; neuroactive steroids; drugs; and toxic metabolites. The literature data analysis revealed the absence of fully validated methods for cerebrospinal fluid analysis, and it presents opportunities for scientists to develop and validate analytical protocols using modern sample preparation techniques, such as microextraction by packed sorbent, dispersive liquid-liquid microextraction, and other potentially applicable techniques.

Comparative Study: Postmortem Long-Term Stability of Endogenous GHB in Cardiac Blood, Femoral Blood, Vitreous Humor, Cerebrospinal Fluid, and Urine with and Without Sodium Fluoride Stabilization

The interpretation of postmortem γ-hydroxybutyric acid (GHB) concentrations is challenging due to endogenous existence and postmortem GHB-production in body tissues and fluids. As an additional complication, formation of GHB was also described in stored postmortem samples. We examined cardiac blood, femoral blood, vitreous humor, cerebrospinal fluid, and urine of eight different corpses (male/female 5/3, aged 33-92 years, postmortem interval 1-6 days) where no intake of GHB or one of its precursors was assumed. All samples were collected during autopsy and divided into two aliquots. To one of the aliquots sodium fluoride (NaF, 1% w/v) was added. Both aliquots were vortexed, further divided into seven aliquots and stored at -20 °C. GHB concentrations were measured immediately and subsequently one day, seven days, two weeks, four weeks, three months, and six months, after sample collection using trimethylsilyl derivatization and gas chromatography, coupled to single quadrupole mass spectrometry (GC-MS). Similar progression curves of GHB concentrations were obtained for the different matrices in the individual corpses. Femoral and cardiac blood GHB concentrations were always found to be higher than in vitreous humor, cerebrospinal fluid, and urine irrespective of stabilization and storage time. None of the obtained GHB concentrations exceed the cut-off values for postmortem matrices commonly used for the identification of an exogenous GHB intake (urine, venous blood, and cerebrospinal fluid: 30 mg/l, cardiac blood, and vitreous humor 50 mg/l). No significant differences were found for the GHB concentrations measured immediately and six months after autopsy. However, we found a significant increase for the GHB concentrations four weeks as well as three months after sample collection which was followed by a decrease nearly to initial values. There were no significant differences between samples with and without NaF addition. The data presented are useful for the interpretation of GHB concentrations in upcoming death cases with special attention to storage conditions and different postmortem matrices.