Development of a UPLC–MS/MS method for determining γ-hydroxybutyric acid (GHB) and GHB glucuronide concentrations in hair and application to forensic cases

Levels of GHB in hair after regular application

Gamma hydroxybutyrate (GHB) is a central nervous system depressant that is an approved drug for the treatment of narcolepsy with cataplexy and other syndromes. Due to its dose dependent stimulating, relaxing or sedative effects, illicit abuses include recreational use by young people and cases of drug-facilitated crime (DFC). Since GHB is also produced endogenously, for forensic questions, it is important to be able to differentiate between endogenous GHB and elevated levels due to additional intake. In this study, we measured GHB concentrations in hair of patients with narcolepsy receiving daily GHB treatment. The results were compared to endogenous concentrations and concentrations after chronic intake presented in several former studies. The aim of this study was to investigate whether a regular intake of a known dosage of GHB leads to elevated levels of GHB concentration in hair. We collected hair samples of 19 patients (14 female, 5 male) with narcolepsy under regular GHB treatment and examined the hair samples segmentally by digestion of the hair followed by liquid-liquid extraction and analysis using a Shimadzu LC20 UFLC system coupled with an AB Sciex API 4000 Qtrap tandem mass spectrometer. All volunteers received daily treatment with different doses of sodium oxybate (sodium salt of GHB) ranging between 3 and 9g per night. The observed mean value of GHB concentration in hair was 2.69ng GHB per mg hair for the 5 male participants, 1.56ng/mg for the 14 female participants giving an overall mean value of 1.86ng/mg for all participants. Our results showed no correlation between the daily dose or the duration intake of GHB and the measured concentration of GHB in hair. Although we did find a significant (p<0.01) difference between published endogenous levels of GHB in hair and GHB levels in hair of patients with regular daily GHB intake, the forensic relevance however is disputable. We hypothesise this narrow margin or even overlap to be the reason why analytical results from hair analysis in some cases fail to provide a reliable prove of a single exposition.

Endogenous GHB in Segmented Hair Part II: Intra-individual Variation for Exogenous Discrimination

The endogenous presence of gamma-hydroxybutyric acid (GHB) complicates the interpretation of results in cases where an exogenous dosing is suspected. Due to GHB’s rapid metabolism and clearance following exogenous doses, hair has become a preferential matrix for confirmation of GHB exposure in drug-facilitated crimes. However, unlike blood and urine where an agreed-upon cut-off concentration for differentiation between endogenous and exogenous GHB has been made, there has been no consensus on a cut-off concentration for hair. This is due in part to the wide inter- and intra-individual variation that has been observed in endogenous GHB hair studies. A large (&gt;50) population study of 214 donors was conducted to better understand these variations and to evaluate whether a cut-off concentration could be established for endogenous GHB in human hair. As seen in our previous study, the inter-individual variation was large, with concentrations ranging from &lt;0.40 to 5.47 ng/mg. This range made an absolute cut-off concentration recommendation inappropriate, so an alternative approach for GHB discrimination was investigated utilizing the intra-individual variation. Male donors appeared to have greater intra-individual variation than female donors, yet it was noted that segment-to-segment variation along the length of hair had minimal change between individual donor’s adjacent segments. Overall, 97.1% of the adjacent segment differences were within ±0.5 ng/mg. Therefore, instead of a recommended cut-off concentration, it appears that using adjacent segment concentration differences could be a strategy to assist in differentiating endogenous from single exogenous GHB exposure. In the absence of controlled dosing data, previously published segmented results from controlled and suspected dosing donors are examined using the adjacent segmental difference approach and the results compared to currently used ratio-based calculations.

Segmental Analysis of R/S-Methamphetamine and R/S-Amphetamine in Abusers' Head Hair

In this study, the relationships between the concentrations of R/S-methamphetamine (MA) and its metabolite R/S-amphetamine (AP), the AP/MA ratio in hair samples, and MA dependence were investigated by performing segmental hair analysis in MA users. Authentic hair samples collected from 10 chronic MA abusers were cut into 1-cm sections (a total of 120 segments). The concentrations of MA and AM enantiomers were quantitatively measured by the LC-MS-MS method. The S-MA concentrations ranged from 1.17 to 256.41 ng/mg and the S-AP concentrations ranged from 0.11 to 23.31 ng/mg in the 120 segments. S-MA and S-AP were the most common analytes identified in hair; no R-MA or R-AP was found. The S-AP/S-MA ratios ranged from 0.03 to 0.32, indicating that the subjects primarily consumed S-MA rather than R-MA or AP. The S-AP/S-MA ratios in the long hair of all chronic MA abusers showed some variation, but there was an overall trend of gradual increase from the distal to the proximal end. This trend was independent of the drug concentrations. Therefore, we could conclude that the AP/MA ratios increased with the duration of MA abuse, and a higher AP/MA ratio suggested high MA dependence. There was no chiral conversion of MA or AP in the hair matrix. The segmental hair analysis showed that all subjects continuously used S-MA, and some users showed an increase in drug dose or the frequency of use.

Endogenous GHB in Segmented Hair Part I: Inter-individual Variation for Group Comparisons

While earlier studies have attempted to resolve the challenges encountered when interpreting gamma-hydroxybutyric acid (GHB) concentrations in hair (primarily due to its endogenous presence), few have had large sample sizes. The first objective of this study was to evaluate the inter-individual variation of endogenous GHB concentrations. The second objective, to be detailed in another report, was to assess intra-individual variation and the impact on exogenous GHB discrimination. Over 2,000 hair segments from 141 women and 73 men (all processed hair 3–12 cm long) were analyzed in this study. The raw calculated range of endogenous GHB concentrations was &lt;0.40–5.47 ng/mg with 97.5% of the segmental results calculated less than 2.00 ng/mg. Imputation, assuming a lognormal distribution, was applied to the data to include non-detect (ND) data (&lt;LOQ), which led to an estimated endogenous GHB range of 0.16–5.47 ng/mg. Kruskal–Wallis tests were employed on a segmental basis for group comparisons. This test was applied to the male and female segmental medians and subsequently indicated that these groups were different at the α = 0.05 level of significance. Additionally, female hair samples appeared to have a trend comprising higher endogenous GHB concentrations close to the scalp and a mean net decrease of ~0.2–0.3 ng/mg distally. Male hair samples displayed the opposite trend, with a mean net increase of ~0.5–0.6 ng/mg from the proximal to the distal end of the hair shaft. It was also concluded that differences exist between the median GHB concentrations of the ‘treated’ and ‘untreated’ hair in the female group at the α = 0.05 level of significance. Age groups and races were analyzed, but none of the observed differences in median concentration were significant at α = 0.05. This is the largest endogenous GHB hair population study to date and provides substantial new data on inter-individual variation and chronological trends of GHB concentrations in hair.

Zwitterionic HILIC stationary phase as a valuable alternative in separative techniques: Application to the analysis of gamma-hydroxybutyric acid and its metabolite in hair

In this work, the physical and chemical properties of a novel zwitterionic LC stationary phase are applied to the development, validation and application of a new fast and reliable method devoted to the analysis of GHB (gamma-hydroxybutyric acid) and its relatively new discovered glucuronide metabolite in hair. The obtained sensitivity, expressed as limit of detection (LOD) and quantification (LOQ), were 0.033 and 0.10 ng/mg for GHB and 0.11 and 0.37 ng/mg, for GHB-glucuronide respectively. Linearity was assessed between LOQ and 50 ng/mg for both compounds. GHB and GHB-glucuronide extraction from hair matrix was maintained simple and consisted in an acidified-solvent incubation. No samples purification was required before LC-MS/MS analysis. The method was finally applied to 65 real hair sample, 60 adults and 5 children below 2 years old. The obtained results highlighted that GHB concentrations were in the range 0.11-0.96 ng/mg (average 0.38 ± 0.25 ng/mg) in 44 cases (68%) while in 21 samples GHB concentrations were in the range between LOD and LOQ (0.033-0.1 ng/mg). GHB-glucuronide was detected in few samples (n. 3) at levels below LOQ. The interest on these molecules relies on the fact that GHB is both a naturally occurring inhibitory neurotransmitter in the central nervous system and an illicit drug often experienced by victims of drug-facilitated sexual assault. GHB-glucuronide was firstly identified in urine by the group of Petersen in 2013 and, as per analogy to ethyl glucuronide, it was proposed as a longer biomarker for GHB intoxication.

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.

Hair analysis in toxicological investigation of drug-facilitated crimes in Denmark over a 8-year period

Hair can serve as a specimen for identifying past drug exposure. Segmental hair analysis may differentiate a single exposure from chronic use. Consequently, segmental hair analysis is useful for disclosing a single drug ingestion, as well as for determining repeated exposures in drug-facilitated crimes (DFCs). This paper presents an overview of toxicological investigations that have used hair analysis in DFC cases from 2009 to 2016 in Denmark. Hair concentrations were determined for 24 DFC-related drugs and metabolites, including benzodiazepines and other hypnotics, antihistamines, opioid analgesics, antipsychotics, barbiturates, and illicit drugs from DFC cases. Drug detection in hair in DFC cases following a single or few intakes of chlorprothixene, codeine, diphenhydramine, oxazepam, oxycodone, promethazine, and phenobarbital is reported for the first time in forensic toxicology. A literature review on concentrations in the published DFC-related hair cases and on concentrations in hair of these substances after single and multiple doses is included. These cases demonstrate the value of segmental hair analysis in DFCs and facilitate future interpretations of results.

A fast method for GHB-GLUC quantitation in whole blood by GC-MS/MS (TQD) for forensic purposes

γ-Hydroxybutyric acid (GHB) is an endogenous compound with a historical use, both in licit and illicit terms. Importantly, the post-mortem behavior of GHB has been studied due to the possibility of using this compound as a biomarker for estimating the post-mortem interval (PMI). However, the post-mortem behavior of the recently discovered glucuronated GHB metabolite (GHB-GLUC) has not been studied. Nevertheless, GHB-GLUC may also have potential both to assist in PMI determination and also to increase the window of detection of GHB consumption. In this work, for the first time, a reliable method using GC-MS/MS for the quantification of GHB-GLUC in whole blood samples was developed and validated, with a simple, fast and cheap sample pretreatment. The method proved to be specific, precise, linear in a work range between 200 and 5000ng/mL, with LOD and LOQ of 52.65ng/mL and 200ng/mL, respectively, and an extraction recovery of 51%. Furthermore, the method was applied to a set of real post-mortem blood samples non-related with GHB intoxication and the obtained results were also discussed.

Potential of GHB phase-II-metabolites to complement current approaches in GHB post administration detection

Recently, phase-II-metabolites of γ-hydroxybutyric acid (GHB), namely GHB-β-O-glucuronide and GHB-4-sulfate, were implemented in the scope of drug testing methods The clearance of GHB from the circulation is extremely fast due to its incorporation into the metabolic pathway of the citrate cycle. The elimination half-life of GHB from blood was reported to be dose dependent between 30 and 50min resulting in narrow detection windows of less than 12h after illicit administration or cases of drug facilitated sexual assault regardless of the biological matrix used. As sulfated metabolites tend to show prolonged half-lives and slower elimination kinetics compared to unmodified or glucuronidated drugs, the potential of GHB-4-sulfate in prolonging the detection of GHB administration was assessed. Its urinary concentrations were determined in n=100 samples from athletes and n=50 samples from sport students, and the resulting data were used to calculate a preliminary reference population-based threshold for urinary GHB-sulfate concentration. The threshold was then compared to concentrations found in post-administration urine samples collected from 3 volunteers who administered GHB within the setting of a clinical trial. Due to the large inter-individual variability of concentrations found in the reference population, GHB-4-sulfate itself was not suitable to prolong the detection times for GHB applications, even when specific gravity-corrected values were used. Therefore, a metabolomics-based approach was applied to the reference population samples and evaluated regarding other urinary metabolites that potentially correlate with the urinary excretion of GHB-4-sulfate and GHB-β-O-glucuronide in order to find a suitable marker to normalize urinary concentrations. The most promising candidate was found at a molecular mass of 321.0696 and was preliminarily identified as β-citryl-glutamic acid.

Determination of GHB and GHB-β-O-glucuronide in hair of three narcoleptic patients-Comparison between single and chronic GHB exposure

Gamma-hydroxybutyric acid (GHB) can be used as a knock-out drug in drug facilitated crime (DFC). Due to its rapid metabolism and resulting narrow detection window, uncovering GHB use in DFC still constitutes a problem. In this experiment we determined the GHB and GHB-β-O-glucuronide (GHB-Gluc) concentrations in hair samples after single and chronic GHB exposures. Hair samples of three narcoleptic patients therapeutically taking sodium oxybate (GHB-sodium-salt) were collected. Patients 1 (P1) and 2 (P2) took the medication for nine and six years, respectively. P1 took daily the pharmaceutical Xyrem^® in a total dose of 5.78g GHB at bed time (2.89g) and four hours (2.89g) later. P2 took a dose of 3.10g GHB at bed time and an additional dose of 2.68g GHB four hours later. Patient 3 (P3) was newly diagnosed with narcolepsy and started his therapy with oral dose of 6g (divided in three portions of 2g GHB) within 24h. The hair samples were extracted both with and without forerunning washing steps. GHB and GHB-Gluc were determined by a published ultra-high performance liquid chromatography-tandem mass spectrometry method using GHB-d₆ and GHB-Gluc-d₄ as internal standards. GHB and GHB-Gluc concentrations in unwashed hair samples of P1 and P2 were determined in a range of 0.56-1.30ng/mg and <0.48-0.85ng/mg, respectively. In washed hair samples of P1 and P2 the concentrations were in a range of <0.32-0.68ng/mg and <0.48-1.20ng/mg for GHB and GHB-Gluc, respectively. The determined concentrations were within the published endogenous range. The confirmed results showed that the washing procedure before extraction causes a minor decrease of GHB concentrations in hair (difference: <1ng/mg). The investigations showed that a single GHB exposure might not be determined by hair analysis of GHB and GHB-Gluc. The chronical intake of therapeutic sodium oxybate with doses up to 7g per night was also not confirmed by hair analysis maybe due to hair treatments. Therefore, GHB hair analysis should be assessed critically and determined negative results could not exclude GHB exposures.

Gamma-Hydroxybutyrate (GHB) Content in Hair Samples Correlates Negatively with Age in Succinic Semialdehyde Dehydrogenase Deficiency

Gamma-hydroxybutyrate (GHB) is a drug of abuse, an approved therapeutic for narcolepsy, an agent employed for facilitation of sexual assault, as well as a biomarker of succinic semialdehyde dehydrogenase deficiency (SSADHD). Our laboratory seeks to identify surrogate biomarkers in SSADHD that can shed light on the developmental course of this neurometabolic disease. Since GHB may be quantified in hair as a potential surrogate to identify victims of drug-related assault, we have opted to examine its level in SSADHD. We quantified GHB in hair derived from ten patients with SSADHD, and documented a significant negative age correlation. These findings are consistent with recent results in patient biological fluids, including plasma and red blood cells. These findings may provide additional insight into the developmental course of SSADHD (Jansen et al., J Inherit Metab Dis 39:795-800, 2016).

Ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) for determination of GHB, precursors and metabolites in different specimens: Application to clinical and forensic cases

Gamma-hydroxybutyric acid (GHB) acts as a precursor and metabolite of the inhibitory central nervous system (CNS) neurotransmitter gamma-aminobutyric acid (GABA). Sodium salt of GHB has been used as a medication for narcolepsy and alcohol withdrawal. Moreover, GHB and its precursor gamma-butyrolactone (GBL), are illegal recreational drugs of abuse. A procedure based on ultra-high-performance liquid chromatography tandem mass spectrometry has been developed and validated in plasma, urine, cerebrospinal fluid and hair for acute and chronic exposure to GHB and in seized preparations coming from black market. In biological matrices, GHB was investigated together with its glucuronide (GHB-Gluc) as a potential marker of exposure, GABA as endogenous precursor and metabolite and GBL as eventual exogenous precursor. GBL was sought together with GHB in illegal preparations. Chromatographic separation was achieved at ambient temperature using a reverse-phase column and an isocratic elution with two solvents: 0.1% formic acid in water and pure methanol. Multiple reaction monitoring (MRM) was used. The method was linear for all analytes under investigation from limit of quantification (LOQ) to 500μgmL^-1 plasma, urine and cerebrospinal fluid, from LOQ to 100ngmg^-1 hair and from LOQ to 10mgmL^-1 illicit preparations with good correlation coefficients (r²=0.99) for all substances. Recovery of analytes under investigation was always higher than 75% and intra-assay and inter-assay precision and accuracy were always better than 15%. The validated method was then successfully applied to real specimens from either forensic (one post-mortem urine sample taken from a GHB fatal intoxication case) or clinical cases (cerebrospinal fluid, plasma and hair samples collected from narcoleptic patients under sodium oxybate treatment). Finally, illicit preparations, seized by police forces were also checked for GHB amount and eventual presence of prodrug GBL.