Endogenous GHB Levels Research Articles

Determination of endogenous GHB levels in chest and pubic hair

Endogenous nature of GHB represents a critical issue for forensic toxicologists, especially in alleged sexual assaults. Therefore, discrimination between physiologically and additional amounts from exogenous sources of such a substance must be effective and reliable in order to avoid severe misinterpretation. This study aimed to quantify the GHB baseline concentrations in chest and pubic hairs collected from 105 healthy volunteers, non-consumers of any drugs of abuse. The final scope was to investigate if these keratin matrices could represent valid alternative to scalp hair when not available. Moreover, we also evaluated the age and gender influences on the GHB baseline levels. 25 mg of hair were incubated overnight with NaOH at 56 °C. After acidification with H2SO4, the solution was liquid-liquid extracted with ethyl acetate and a trimethylsilyl derivatization was then achieved. Analysis was performed in gas chromatography-mass spectrometry in single ion monitoring mode (m/z 233, 234, 147 for GHB; m/z 239, 240 and 147 for GHB-d6). The endogenous amount in “blank” hair was estimated by the standard addition method (0.301 for chest hair and 0.235 ng/mg for pubic hair). GHB concentration ranged from 0.205 to 1.511 ng/mg for chest hair and from 0.310 to 1.913 ng/mg for pubic hair. These values were consistent with previous studies on scalp hair and on pubic hair. Unfortunately, research on chest hair is not available in literature. T-Test and Linear Regression highlighted no statistically significant differences for the two matrices and for all age/gender sub-groups. However, further studies are required to estimate a reliable cut-off value for these keratin matrices. For the first time, we demonstrated the suitability of chest and pubic hair to detect endogenous levels of GHB.

Determination of GHB levels in breast milk and correlation with blood concentrations

The sodium salt of GHB or sodium oxybate is approved and registered in some countries as a therapeutic substance (Xyrem®) for the treatment of narcolepsy-associated cataplexy. This study was designed to measure the GHB endogenous levels in blood and breast milk of 20 breastfeeding women. In addition, blood and breast milk samples of a 32-year-old narcoleptic nursing mother, who was on sodium oxybate treatment, were simultaneously collected at 0.5, 1, 3, 4 and 5h following a 4.5g GHB dose and analyzed, in order to establish the safety interval of time to breastfeed. A GC–MS method for the detection and quantification of GHB in blood and breast milk was developed and fully validated. The geometric mean of endogenous GHB levels in blood and breast milk detected at time 0 were 0.57mg/L; 95% Reference Interval (RI): 0.21–1.52mg/L and 0.36mg/L; 95% RI: 0.13–1.03mg/L, respectively. The geometric mean of the concentration of GHB in milk was 37% less (95% RI: from 14 to 53%) compared to that found in the blood.The analysis of blood and breast milk samples collected from the 32 years-old female showed the following results: GHB blood concentration 0.5h after medication intake was 80.10mg/L, reaching the peak 1h after the drug administration (108.34mg/L) and it steadily decreased to reach a level of 1.75mg/L, 5h after the medication intake. The GHB concentration found in breast milk followed the same pattern as for the blood, with the highest concentration being 23.19mg/L, 1h after sodium oxybate administration and the lowest 0.99mg/L, 5h after the medication's intake. The comparison between blood and breast milk GHB levels in the 32-year-old woman, showed significant lower GHB levels in milk at 0.5, 1 and 3h, ranging from 71 to 80% less. It is interesting to note that only at 4 and 5h the difference between blood and breast milk GHB levels fell within the 95% RI (14–53%) of endogenous levels.Taking into consideration the absence of reference values for endogenous GHB in milk, we suggest the following reference interval: 0.13–1.03mg/L.We would recommend, following these preliminary data, that nursing mothers under sodium oxybate treatment should breastfeed at least 5h after the last GHB administration. However, further studies are necessary in order to confirm these findings.

An improved method for the analysis of GHB in human hair by liquid chromatography tandem mass spectrometry.

The abuse of gamma-hydroxybutyric acid (GHB) and its suspicion in cases of suspected drug-facilitated sexual assault is of keen interest to forensic toxicology laboratories. This paper reports an extraction, separation and detection procedure for GHB in hair utilizing a combination of liquid-liquid extraction and solid-phase extraction using ethyl acetate and Oasis Max(®) cartridge, respectively, after the hair sample was digested. Analysis was by LC-MS-MS using a gradient separation on an Acclaim(®) Trinity(TM) P1 column performing three multiple-reaction monitoring (MRM) transitions each for GHB and its internal standard. The procedure was validated over a range from 0.4 to 50 ng/mg with estimated limit of detection (LOD) of 0.33 and an administratively set limit of quantitation (LOQ) of 1.2 ng/mg. Twenty hair specimens collected from individuals with no known exposure to GHB were analyzed for matrix interferences and to establish initial background levels of GHB. A wide range of endogenous GHB levels were observed in these samples (from less than the LOQ to 4.4 ng/mg). The results suggest the need for additional studies to better establish the full range of endogenous GHB levels in hair and that extreme caution is required in interpreting GHB findings in hair samples.

Synthesis and stability study of a new major metabolite of γ-hydroxybutyric acid.

γ-Hydroxybutanoic acid (GHB) is used as a date-rape drug, which renders the victims unconscious and defenceless. Intoxications are very difficult to detect for forensic scientists due to rapid metabolism to endogenous levels of GHB. We recently discovered a new major metabolite, 2, of GHB (1) that could potentially extend the analytical detection window for GHB intoxications. Herein we disclose synthetic procedures based on a Koenigs–Knorr glucuronidation approach that provides GHB glucuronide 2 and a deuterium-labelled analogue d4-2 of high purity suitable for analytical chemistry. In addition, we have assessed the stability of GHB glucuronide 2 by mimicking the natural pH range for urine, which is of importance in the development of new analytical methods. Using NMR we show that GHB glucuronide 2 is highly stable towards aqueous hydrolysis within the pH range normally observed for urine even at elevated temperature.

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 γ-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 μg/ml in smokers, 0.28±0.21 μg/ml in nonsmokers/nondrinkers, and 0.23±0.04 μg/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.

Determination of endogenous gamma-hydroxybutyric acid (GHB) levels in antemortem urine and blood

Gamma-hydroxybutyric acid’s (GHB’s) natural presence in the body has made the interpretation of its levels a challenging task for the forensic toxicologist. This study was designed to measure endogenous GHB levels in antemortem urine and blood samples. The range detected in urine was from 34 to 575μg/dl and in blood from 17 to 151μg/dl. The results indicate that the concentration of endogenous GHB in urine and blood concur with the suggested cut-off levels at 1000 and 500μg/dl, respectively.

Effect of storage temperature on endogenous GHB levels in urine

Because γ-hydroxybutyrate (GHB) is an endogenous substance present in the body and is rapidly eliminated after ingestion, toxicologists investigating drug-facilitated sexual assault cases are often asked to differentiate between endogenous and exogenous levels of GHB in urine samples. This study was designed to determine the effects of storage temperature on endogenous GHB levels in urine. Specifically, it was designed to ascertain whether endogenous levels can be elevated to a range considered indicative of GHB ingestion. Urine specimens from two subjects that had not been administered exogenous GHB were collected during a 24 h period and individually pooled. The pooled specimens were separated into standard sample cups and divided into three storage groups: room temperature (∼25°C), refrigerated (5°C), and frozen (−10°C). Additionally, some specimens were put through numerous freeze/thaw cycles to mimic situations that may occur if multiple laboratories analyze the same specimen. Periodic analysis of the samples revealed increases in the levels of endogenous GHB over a 6-month period. The greatest increase (up to 404%) was observed in the samples maintained at room temperature. The refrigerated specimens showed increases of 140–208%, while the frozen specimens showed smaller changes (88–116%). The specimens subjected to multiple freeze/thaw cycles mirrored specimens that had been thawed only once. None of the stored urine specimens demonstrated increases in GHB concentrations that would be consistent with exogenous GHB ingestion.

Gammahydroxybutyrate: An endogenous regulator of energy metabolism

Gammahydroxybutyrate is a naturally occurring metabolite of many mammalian tissues. Although its administration produces a wide range of pharmacological effects, its normal function has never been clearly defined. GHB can induce NREM and REM sleep, anaesthesia, hypothermia, and a trance-like state which has been considered a model for petit mal epilepsy. It markedly increases brain dopamine levels. It has been touted as a central neurotransmitter or neuromodulator, and high affinity brain receptors, as well as central mechanisms for its synthesis, uptake and release have been demonstrated in support of this. But GHB is also found in many peripheral tissues and in some of these in higher concentrations than in the brain. No explanation has been offered for its presence in these tissues. A number of studies indicate that GHB can reduce energy substrate consumption in both brain and peripheral tissues, and that it can protect these tissues from the damaging effects of anoxia or excessive metabolic demand. Indeed there is some evidence to suggest that endogenous GHB levels rise under these circumstances. GHB appears to act through the endogenous opioid system, since in the brain, at least, GHB raises dynorphin levels and its metabolic and pharmacological effects can be blocked by naloxone. These, and other observations detailed in this review, suggest that GHB may function naturally in the induction and maintenance of physiological states, like sleep and hibernation, in which energy utilization is depressed. GHB may also function naturally as an endogenous protective agent when tissue energy supplies are limited.

REGIONAL BRAIN LEVELS OF γ‐HYDROXYBUTYRATE IN HUNTINGTON'S DISEASE

Abstract—A highly sensitive electron capture gas chromatographic method was developed for quantitation of γ‐hydroxybutyrate (GHB) in tissue. This method involves an improved, extraction and purification procedure and a one‐step derivatization of GHB to the methyl ester‐O‐heptafluorobutyrate. As low as 5 ng of GHB in tissue was accurately quantitated by this method.By means of this improved method, endogenous levels of GHB in several regions of brains obtained post‐mortem from patients with Huntington's disease were determined, and compared with brain samples obtained post‐mortem from non‐neurological controls. The levels of GHB found in the caudate and substantia nigra obtained from Huntington's patients were significantly higher than the GHB levels found in similar regions of brain obtained from a non‐neurological control group. The content of GABA in the same choreic and control brain samples was also determined. No significant correlation between changes in GHB and GABA levels was observed although there was a trend towards an inverse relationship. The high level of GHR in Huntington's disease may be related to the decrease in succinate:oxidoreductase (EC 1.3.99.1) activity reported by Stahl & Swanson (1974).In two subjects (one control and one Huntington patient) the zonal distribution of GHB in substantia nigra was also determined. The zona reticulata from choreic brain contained a substantially higher level of GHB, whereas the zona compacta contained an amount similar to the level found in control brain.