Monitoring of phosphatidylethanol in dried blood spots and of ethyl glucuronide in hair over 6 months of alcohol consumption

The aim of this study was to monitor seven phosphatidylethanol (PEth) homologues in dried blood spots (DBS) and ethyl glucuronide in hair (EtGH) over a 6-month period of drinking while documenting the daily drinks (amount and type) of alcohol via app. A total of 23 volunteers (12 males and 11 females) aged 19-54 years were enrolled. At four-weekly intervals, capillary blood to create DBS and after 3 and 6 months, respectively, a strand of hair (proximal, 3 cm) was collected. Analyses of EtGH and PEth homologues were performed using liquid chromatography-tandem mass spectrometry. All participants consumed alcohol during the 6 months. Only one participant tested negative for both PEth and EtGH. Eight participants had PEth 16:0/18:1 concentrations between 20 and <210 ng/mL (mean: 45.6 ng/mL) but EtGH concentrations below 5 pg/mg. PEth 16:0/18:1 concentrations between 20 and <210 ng/mL and EtGH concentrations between 5 and <30 pg/mg were assigned to eight subjects, uniformly matching them in the category of socially accepted drinking behavior. Four test subjects exceeded the cutoff for social drinking behavior in both PEth 16:0/18:1 (mean: 528 ng/mL) and EtGH (mean: 84.5 pg/mg). Two participants exceeded the threshold for PEth 16:0/18:1 of 210 ng/mL in blood but remained below 30 pg EtG/mg hair. PEth showed a higher detection rate for alcohol consumption than EtGH did. Moreover, PEth concentrations reacted quickly to changes in drinking behavior, whereas EtGH concentrations remained similar over time.

Single hair analysis for gamma-hydroxybutyric acid-Method optimization, validation, and application

As gamma-hydroxybutyric acid (GHB) underlies fast metabolization, its determination from hair may presumably offer a detection window superior to that of body fluids. Due to the wide range of endogenous concentration levels, the evidence of an exogenous ingestion is challenging. As already shown for other drugs, the temporal resolution obtained by applying single hair microanalysis provides further information. Therefore, a method for the extraction and quantification of GHB in 2-mm hair segments (seg) was optimized and validated (limit of detection [LOD]: 2.5 pg/seg, lower limit of quantification [LLOQ]: 5 pg/seg), and five single hairs were examined, each for three non-users and for three (alleged) users. A major challenge was the choice of appropriate extraction tubes without remains of GHB. In two samples from non-users, GHB could not or could only be detected in trace amounts. In the third sample, concentrations between the LOD and 31.1 pg/seg (mean: 9.5, median: 8.4; each pg/seg) were detected with decreasing values towards the tips. In two samples of persons with assumed GHB intake, maximum concentrations of 6.8 and 30.7 pg/seg were measured, but no significant concentration peaks indicating a single ingestion could be observed. The third sample showed concentrations of 7.6-55.2 pg/seg (mean: 28.8, median: 29.6; each pg/seg). In this case, the obtained profiles showing at least two reproducible concentration maxima between 20 and 40 mm point to an ingestion of GHB. The concentration profiles from single hairs were reproducible in each case, reflecting the concentration course of routine 1-cm segmental analysis. These are the first results published on GHB testing in segmented single hairs, and the results must be verified further.

Storage stability of phosphatidylethanol homologues in whole blood and dried blood spots of nonalcoholics at different temperatures over 60 days

Phosphatidylethanol (PEth) has recently become a popular direct alcohol marker for evaluating drinking behavior. This study aimed at gaining further information on the long-term stability of five PEth homologues (16:0/18:1, 16:0/18:2, 16:0/20:4, 18:0/18:1, 18:0/18:2) in whole blood (WB) and dried blood spots (DBS) stored at -80°C, 4°C, and room temperature (18°C) over a period of 60 days. Venous blood was taken from 10 volunteers (five females and five males, aged 21-40 years) with a moderate drinking behavior and a negative breath alcohol test at the time of collection. 100 μL aliquots of WB were prepared in addition to 20 μL DBS samples. The initial PEth concentrations were determined on the day of the blood collection. On days 1, 3, 5, 7, 11, 17, 40, and 60, DBS were analyzed in triplicate by means of LC-MS/MS. On these days, WB aliquots having been stored until that time were used to create further DBS in triplicate, which were subsequently stored at 18°C and analyzed in a single batch after day 60. All homologues, except PEth 16:0/20:4, were stable at -80°C in DBS and WB for 60 days. The initial PEth 16:0/18:1 concentrations remained stable in both DBS and WB in all but one volunteer's specimen at 4 and 18°C. Apart from this exception, simultaneously detected PEth homologues 16:0/18:2, 18:0/18:1, and 18:0/18:2 remained stable over at least 40 days in DBS. Nevertheless, the storage time between sample collection and analysis should be kept as short as possible if an ethanol-free sample cannot be ensured.

Formation of phosphatidylethanol and ethylglucuronide after low to moderate alcohol consumption in volunteers with a previous three-week alcohol abstinence

AIMS

Phosphatidylethanol (PEth) is only formed when ethanol is present in blood. This direct alcohol marker has been widely discussed, including the minimum amount of ethanol being necessary to form as much PEth as to exceed the threshold of 20 ng/mL in previously PEth negative subjects. In order to corroborate hitherto existing results, a drinking study including 18 participants after a 3-week alcohol abstinence was performed.

METHODS

They consumed a pre-calculated amount of ethanol to reach a blood alcohol concentration (BAC) of at least 0.6 g/kg. Blood was drawn before and periodically seven times after alcohol administration on day 1. Blood and urine were also collected the next morning. Dried blood spots (DBS) were prepared immediately from collected venous blood. BAC was determined by head space gas chromatography and the concentrations of both PEth (16:0/18:1, 16:0/18:2 and five additional homologues) and ethyl glucuronide (EtG) were analysed using liquid chromatography-tandem mass spectrometry.

RESULTS

Out of 18, 5 participants had concentrations of PEth 16:0/18:1 above the threshold of 20 ng/mL, and 11 out of the 18 subjects had concentrations between 10 and 20 ng/mL. In addition, four persons had PEth 16:0/18:2 concentrations above 20 ng/mL the following morning. All test subjects tested positive for EtG in DBS (≥ 3 ng/mL) and urine (≥100 ng/mL) upon 20-21 h after alcohol administration.

CONCLUSION

By combining both a lower cutoff of 10 ng/mL and the homologue PEth 16:0/18:2, the sensitivity to detect a single alcohol intake after a 3-week abstinence increases to 72.2%.

Development and Validation of Seven Phosphatidylethanol Homologues in Dried Blood Spots Including Preliminary Results after Excessive Use of an Ethanol-Based Hand Sanitizer

Phosphatidylethanol (PEth) has become a widespread marker offering an up to 4-week retrospective window to detect alcohol use. Due to the pandemic of coronavirus disease 2019, ethanol-based hand sanitizers are frequently used. The aim of this study was to develop and validate a method for the determination of up to seven different homologues of PEth from dried blood spots (DBSs) after use of an ethanol-based hand sanitizer. The objectives of its preliminary application were to prove whether a threshold of 20 ng/mL for PEth 16:0/18:1 is reached and whether other homologues are formed as well as if positive findings of urinary ethyl glucuronide (UEtG) can be observed with respect to assess monitoring of abstinence control programs. Ten volunteers (8 occasional and 2 regular drinkers) were recruited to excessively use an ethanol-based hand sanitizer on 5 successive days. DBSs and urine samples were collected daily. PEth and UEtG were determined by liquid chromatography--tandem mass spectrometry. In total, two volunteers with initial PEth 16:0/18:1 concentrations of 19.3 and 14.6 ng/mL exceeded the threshold of 20 ng/mL six times. Subjects drinking daily or almost daily had starting PEth 16:0/18:1 concentrations of 242 and 354 ng/mL, showing a decline of PEth concentrations in six out of the seven homologues over 5 days. In teetotalers, formation of PEth species could not be observed. Thus, not satisfying requirements in an alcohol monitoring program with initial PEth-negative blood cannot be explained by a frequent use of ethanol-based hand sanitizer only. In cases of regular alcohol consumption, PEth homologues are not likely to be further influenced. However, results indicated that individuals with a PEth concentration close to 20 ng/mL are at risk of exceeding the threshold by using ethanol-based hand sanitizer.

Will tetrahydrocannabinol be formed from cannabidiol in gastric fluid? An in vivo experiment

Cannabidiol (CBD) products have ascribed an uprising trend for their health-promoting effects worldwide. In contrast to Δ⁹-tetrahydrocannabinol (THC), CBD exhibits no state of euphoria. Since conversion of CBD into THC in an acidic environment has been reported, it has not been proved whether this degradation will also occur in human gastric fluid. A total of 9 subjects ingested 400 mg CBD as a water-soluble liquid together with lecithin as an emulsifier and ethanol as a solubilizer. Blood samples were taken up to 4 h, and urine samples were submitted up to 48 h. THC, 11-hydroxy-Δ⁹-THC (THC-OH), 11-nor-9-carboxy-Δ⁹-THC (THC-COOH), CBD, 7-hydroxy cannabidiol (7-OH-CBD), and 7-carboxy cannabidiol (7-CBD-COOH) were determined in blood and THC-COOH and 7-CBD-COOH in urine by LC-MS/MS. Neither THC, THC-OH, nor THC-COOH were detectable in any serum specimen. Only two urine samples revealed THC-COOH values slightly above the threshold of 10 ng/ml, which could also be caused by trace amounts of THC being present in the CBD liquid. It can be concluded that negative consequences for participants of a drug testing program due to a conversion of CBD into THC in human gastric fluid appear unlikely, especially considering a single intake of dosages of less than 400 mg. Nevertheless, there is a reasonable risk for consumers of CBD products being tested positive for THC or THC metabolites. However, this is probably not caused by CBD cyclization into THC in human gastric fluid but is most likely due to THC being present as an impurity of CBD products.

The effect of creatine ingestion on urinary creatinine concentration: Does supplementation mask a heavy dilution?

A high volume of fluid can strongly reduce a drug's concentration in urine. Therefore, to detect diluted samples, the concentration of creatinine in urine is determined during testing drugs of abuse. If the concentration is below 20 mg creatinine/dl urine, the urine sample is usually rejected for drug testing. It should be examined whether creatine or creatinine ingestion can mask urine dilution by increasing the creatinine concentration. A total of 18 subjects drank 1.3 L of water and 0.2 L of orange juice on each of the three testing days: (1) without creatine, (2) with 20 g of creatine, and (3) with 20 g of creatine following incubation for 4 days in orange juice at room temperature; an acidic environment should promote conversion of creatine to creatinine. The lowest creatinine concentrations in urine were observed on average 2 h after fluid intake. At that time, ingestion of fluid without creatine, with creatine, and with creatine(ine)-orange juice mixture resulted in mean values of 11.6, 22.5, and 28.3 mg creatinine/dl urine, respectively. It can be concluded that ingestion of creatine or creatinine can increase the concentration of creatinine in urine and thus mask dilution of a sample. The conversion of creatine in orange juice further increases availability of creatinine as it is obvious from urine creatinine concentration. Therefore, creatine ingestion during drug testing will give rise to negative results due to matrix adulteration. In a case of suspected creatine supplementation, the creatine content of the sample should be determined in addition to creatinine.

Oral Yohimbine as a New Probe Drug to Predict CYP2D6 Activity: Results of a Fixed-Sequence Phase I Trial

Objective

Yohimbine pharmacokinetics were determined after oral administration of a single oral dose of yohimbine 5 mg and a microdose of yohimbine 50 µg in relation to different cytochrome P450 (CYP) 2D6 genotypes. The CYP2D6 inhibitor paroxetine was used to investigate the influence on yohimbine pharmacokinetics. Microdosed midazolam was applied to evaluate a possible impact of yohimbine on CYP3A activity and the possibility of combining microdosed yohimbine and midazolam to simultaneously determine CYP2D6 and CYP3A activity.

Methods

In a fixed-sequence clinical trial, 16 healthy volunteers with a known CYP2D6 genotype [extensive (10), intermediate (2) and poor (4) metaboliser] received an oral dose of yohimbine 50 µg, yohimbine 5 mg at baseline and during paroxetine as a CYP2D6 inhibitor. Midazolam (30 µg) was co-administered to determine CYP3A activity at each occasion. Plasma concentrations of yohimbine, its main metabolite 11-OH-yohimbine, midazolam and paroxetine were quantified using validated liquid chromatography-tandem mass spectrometry assays.

Results

Pharmacokinetics of yohimbine were highly variable and a CYP2D6 genotype dependent clearance was observed. After yohimbine 5 mg, the clearance ranged from 25.3 to 15,864 mL/min and after yohimbine 50 µg, the clearance ranged from 39.6 to 38,822 mL/min. A more than fivefold reduction in clearance was caused by paroxetine in CYP2D6 extensive metabolisers, while the clearance in poor metabolisers was not affected. Yohimbine did not alter CYP3A activity as measured by microdosed midazolam.

Conclusions

The pharmacokinetics of yohimbine were highly correlated with CYP2D6, which was further supported by the clearance inhibition caused by the CYP2D6 inhibitor paroxetine. With these data, yohimbine is proposed to be a suitable probe drug to predict CYP2D6 activity. In addition, the microdose can be used in combination with microdosed midazolam to simultaneously evaluate CYP2D6 and CYP3A activity without any interaction between the probe drugs and because the microdoses exert no pharmacological effects.

Clinical Trial Registration

EudraCT2017-001801-34.

Electronic supplementary material

The online version of this article (10.1007/s40262-020-00862-6) contains supplementary material, which is available to authorized users.

Return of the Quaaludes? Prolonged agitated delirium after intentional ingestion of the methaqualone analog SL-164 - a case report

Background: A 22-year-old male with a known history of drug abuse presented to our department with prolonged agitated delirium, myocloni, tachycardia and subfebrile temperature after the deliberate ingestion of opium poppy tea (Papaver somniferum L.) together with the methaqualone analog SL-164 (5-chloro-3-(4-chloro-2-methylphenyl)-2-methyl-4(3H)-quinazolinone) which is sold online as a designer drug. Methods: SL-164 and its hydroxy metabolites were detected in serum and urine via liquid chromatography-quadrupole-time-of-flight mass spectrometry (LC-QTOF-MS). Results: The pronounced delirium was treated with benzodiazepines and neuroleptics; temporary medical restraint had to be applied. Symptoms completely resolved over the next 72 h and the patient was discharged on day three able to give consent. Conclusions: Although methaqualone was a popular and widespread sedative in the 1950s and 60 s before its discontinuation in the USA in 1985, derivatives of the methaqualone class have not previously played a large role as drugs of abuse in the rapidly growing market of new psychoactive substances. To our knowledge, this is the first case of agitated delirium with detection of SL-164 and hydroxylated metabolites in a patient's serum and urine.

Verifying the validity of creatinine measurement in low-concentrated urine spot samples-Photospectrometry versus liquid chromatography-tandem mass spectrometry

One of the major challenges of testing drugs of abuse is the detection of highly diluted urine samples. The ingestion of a large amount of fluid can considerably reduce the concentration of substances, possibly resulting in inaccurate drug testing. For detection, determination of urinary creatinine is a widely established procedure. In this study, results from the most popular methods, including photospectrometry (Jaffe) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), have been compared regarding 327 urine abstinence control samples. Because samples with creatinine concentrations close to the cutoff of 20 mg/dL are of particular interest, only samples below 50 mg/dL were considered. Results revealed a close correlation of creatinine concentrations by both analytical methods with an R² value of 0.9005. A mean concentration difference of 3.30 ± 3.45 mg/dL was observed, indicating a moderate underestimation by the Jaffe reaction. Graphical analyses showed high accordance between both methods with only a few outliers. Due to easy handling and for economic reasons, the spectrometric method is often preferred over LC-MS/MS. For urine samples with creatinine concentrations close to the cutoff, confirmation through a second method should be performed to avoid a possible disadvantage or even severe consequences for the respective individual. It is recommended that each laboratory establishes a reliable verification method.

Single hair analysis: Validation of a screening method for over 150 analytes and application on documented single-dose cases

Hair is the matrix of choice in forensic toxicology when retrospective analysis is needed. Nonetheless, due to misalignment, different growth stages and segmentation lengths of 0.5-1 cm, resolution of time is limited. By segmental analysis of single hairs, most of these factors can be compensated and resolution of time is enhanced. A method for manually segmenting single hairs in 2-mm sections and screening for 156 analytes by liquid chromatography coupled to tandem mass spectrometry has been developed and validated. The method was applied to 15 single-dose cases concerning different pharmaceuticals by analyzing 10 hairs each, sampled 1 and 2 months after ingestion in most cases. The validation showed a lower limit of quantification of ≤1.25 pg/segment for ~90% of analytes and good accuracy. Many substances could be detected in the presented cases, whereas detection of benzodiazepines and low dosed opioids remains challenging. In positive cases, characteristic peak-shaped concentration profiles across the hairs were obtained. The segment with most coinciding peak maxima can be allocated to the time of ingestion. A method for the determination of individual hair growth rate was applied and revealed a gap between expected and actual position of peak maxima. Additionally, different localization of simultaneously administered substances was observed. These findings were tried to be explained by different routes of incorporation and may contribute to current knowledge. The presented method may directly be applied to similar questions in hair analysis, and the findings are considered important for interpreting further results in single hair analysis.

Minor contribution of cytochrome P450 3A activity on fentanyl exposure in palliative care cancer patients

Transdermal fentanyl is widely used to control pain in cancer patients. The high pharmacokinetic variability of fentanyl is assumed to be due to cytochrome P450 3A-mediated (CYP3A) N-dealkylation to norfentanyl in humans. However, recently published clinical studies question the importance of the described metabolic pathway. In this small study in palliative cancer patients under real-life clinical conditions, the influence of CYP3A on fentanyl variability was investigated. In addition to the determination of midazolam plasma concentration to reveal CYP3A activity, plasma concentrations of fentanyl and its metabolite, norfentanyl, were measured in identical blood samples of 20 patients who participated in an ongoing trial and had been on transdermal fentanyl. Fentanyl, norfentanyl, midazolam, and 1′-OH-midazolam were quantified by liquid chromatography/tandem mass spectrometry. Plasma concentrations of fentanyl and norfentanyl exhibited a large variability. Mean estimated total clearance of fentanyl and mean metabolic clearance of midazolam (as a marker of CYP3A activity) were 75.5 and 36.3 L/h. Both clearances showed a weak correlation and hence a minimal influence of CYP3A on fentanyl elimination.

Creatinine excretion in consecutive urine samples after controlled ingestion of water

Highly diluted urine is among the most commonly observed factors affecting the validity of urine testing for drug abuse. A minimum creatinine concentration of 20 mg/dL urine has been proposed as a marker for dilution of a urine sample. This study investigates the effect of water consumption on creatinine concentration, as well as its effect on specific gravity and osmolality. In this study, 22 subjects (17 women and 5 men) were included to determine the influence of sex and weight on the impact of excessive water consumption on these markers of urine dilution. The subjects consumed 0.5 L, 1.0 L, and 1.5 L of water, respectively, within 15 minutes. The mean minimum creatinine concentrations (Jaffé reaction) for the void 2 hours after fluid intake were 60.4 mg/dL, 15.8 mg/dL, and 10.9 mg/dL for the respective ingested volumes of water. Mean creatinine concentrations excreted by men were significantly higher than those excreted by women. Participants with a weight below 60 kg tended to excrete lower urine creatinine concentrations. 50% of the volunteers with a BMI < 20 kg/m² and 20% of the volunteers with a BMI > 20 kg/m² exhibited creatinine concentrations below the threshold value of 20 mg/dL. A similar pattern was established for gravity and osmolality. Due to its simple determination, creatinine may be preferred over specific gravity or osmolality. In order to evaluate the internal dilution of a urine sample for legally defensible drug testing, it may be necessary to account for sex and body weight.

Proof of active cannabis use comparing 11-hydroxy-∆9-tetrahydrocannabinol with 11-nor-9-carboxy-tetrahydrocannabinol concentrations

Testing hair for cannabis use has increasingly been scrutinised due to exposure to second-hand smoke or environmental contamination. Confirmation of drug use involving detection of metabolites such as 11-nor-9-carboxy-delta-9-tetrahydrocannabinol (THC-COOH) and 11-hydroxy-delta-9-tetrahydrocannabinol (THC-OH) having very rarely been considered. We developed a new, simplified procedure with regard to expenditure of time and material to determine delta-9-tetrahydrocannabinol (THC, qualitatively), as well as THC-OH and THC-COOH (quantitatively) from 587 hair samples by liquid chromatography-tandem mass spectrometry (LC-MS/MS) which was compared to hitherto established methods (n = 3). Compared to conventional methanolic extraction alkaline dissolution resulted in higher concentrations for THC-OH. Concentrations determined from specimens ranged from 0.01 to 18.7 ng THC/mg hair, 0.05-37.6 pg THC-OH/mg hair, and from 0.1 to 54.3 pg THC-COOH/mg hair. THC was detectable in 70.4% samples along with both metabolites from more than half of these samples. In 12.9% of THC-positive cases, neither THC-OH nor THC-COOH were present. In 8.9% of THC-negative cases, it was possible to detect metabolites either alone or in combination. THC-OH could more frequently be detected than THC-COOH and appeared to be less susceptible to cosmetic treatment. In summary, THC-OH turned out to be a further suitable marker to prove cannabis use. Determination of both metabolites is recommended to unequivocally differentiate consumption from external exposure or contamination.

Extracorporeal life support and digoxin-specific Fab fragments for successful management of Taxus baccata intoxication with low output and ventricular arrhythmia

INTRODUCTION

Yew plants are evergreen shrubs which are widely spread throughout the northern hemisphere. Taxane alkaloid derivatives, mainly taxine B, represent the main toxins of Taxus baccata and are highly cardiotoxic. Due to the lack of randomized clinical trials, case reports on accidental or suicidal yew intoxications build the only source of knowledge of clinical treatment options.

CASE REPORT

We report the case of a suicidal yew ingestion admitted to our hospital under prolonged cardiopulmonary resuscitation due to pulseless electrical activity. Extra-corporeal life support (ECLS) was established to maintain adequate organ perfusion. Repeated administration of digoxin-specific Fab antibody fragments, which cross-react with taxine, was associated with an immediate conversion from asystole to broad-complex bradycardia and a gradual normalization of the electrocardiogram (ECG). This was paralleled by a recovery of the cardiac function and weaning from the ECLS. The taxine metabolite 3,5-dimethoxyphenol could be detected by mass spectrometry before but not after the first Fab-fragment treatment. In contrast, the total amount of taxine (including the neutralized, Fab fragment-bound fraction) was increased after each Fab fragment administration, suggesting an accumulation of neutralized, since antibody-bound taxine in the blood by anti-digoxin Fab fragments.

DISCUSSION

In conclusion, the successful clinical course of this case suggests a benefit of an early anti-digoxin Fab-fragment administration for the treatment of yew intoxication.

Is it possible to detect PEth 16:0/18:1 and PEth 18:1/18:1 in red blood cells after 20 years of storage in liquid nitrogen?

INTRODUCTION

Phosphatidylethanol (PEth), as measured in freshly drawn blood samples, could be a promising new biomarker for habitual alcohol consumption, but it is still unknown whether PEth can also be determined from blood samples having been stored frozen for a longer period.

MATERIALS AND METHODS

PEth 16:0/18:1 and PEth 18:1/18:1 were determined by LC-MS/MS from red blood cells (RBC) derived from blood samples of (I) 20 healthy volunteers (after 1 month of storage at -80 °C) and (II) 232 participants of the population-based European Prospective Investigation into Cancer and Nutrition (EPIC)-Heidelberg study (after 20 years of storage at -196 °C). Analyses involved liquid-liquid extraction from 100 μl aliquots with phosphatidylpropanol (PProp 18:1/18:1) as the internal standard. Extracts were subjected to a 10-min LC gradient separation, using multiple reaction monitoring of deprotonated molecules for quantification.

RESULTS

After 1 month of storage at -80 °C, PEth was detectable in all samples at mean concentrations of 393.6 ± 12.4 ng/ml (PEth 16:0/18:1) and 43.3 ± 1.1 ng/ml (PEth 18:1/18:1). In samples stored for 20 years at -196 °C, PEth was detectable in 23.7% of all samples at mean concentrations of 412.2 ± 655.5 ng/ml (PEth 16:0/18:1) and 38.0 ± 74.8 ng/ml (PEth 18:1/18:1).

DISCUSSION AND CONCLUSION

PEth can be determined reliably from samples of moderate habitual alcohol consumers after 1 month of storage at -80 °C. Our data suggest that PEth is generally also detectable in samples after 20 years of storage at -196 °C. Further studies are needed to assess the still unknown impact of storage duration and temperature on different PEth specimen concentrations.

Use of Fentanyl in Adolescents with Clinically Severe Obesity Undergoing Bariatric Surgery: A Pilot Study

BACKGROUND

The number of obese pediatric patients requiring anesthesia is rapidly increasing. Although fentanyl is a commonly used narcotic during surgery, there are no pharmacokinetic (PK) data available for optimal dosing of fentanyl in adolescents with clinically severe obesity.

MATERIALS AND METHODS

An institutional review board-approved exploratory pilot study was conducted in six adolescents aged 14-19 years undergoing bariatric surgery. Mean total body weight (TBW) and mean BMI were 137.4 ± 14.3 kg and 49.6 ± 6.4 kg/m² (99.5th BMI percentile), respectively. Fentanyl was administered intravenously for intraoperative analgesia based on ideal body weight per standard of care. PK blood samples were drawn over a 24-h post-dose period. Fentanyl PK parameters were calculated by non-compartmental analysis.

RESULTS

Mean fentanyl AUC_0-∞ was 1.5 ± 0.5 h·ng/mL. Systemic clearance of fentanyl was 1522 ± 310 mL/min and 11.2 ± 2.6 mL/min·kg TBW. Volume of distribution was 635 ± 282 L and 4.7 ± 2.1 L/kg TBW. While absolute clearance was increased, absolute volume of distribution was comparable to previously established adult values.

CONCLUSIONS

These results suggest that fentanyl clearance is enhanced in adolescents with clinically severe obesity while volume of distribution is comparable to previously published studies.

STUDY REGISTRATION

NCT01955993 (clinicaltrials.gov).

Formation and inhibition of ethyl glucuronide and ethyl sulfate

Ethyl glucuronide (EtG) und ethyl sulfate (EtS) are widely accepted biomarkers in forensic and clinical settings. Even though, levels of EtG and EtS in blood and urine increase with increasing doses of alcohol, a high inter-individual variability in their production has been noticed. Therefore, we investigated the influence of dietary plant phenols on the formation of EtG and EtS and tentatively estimated the magnitude of in vivo inhibitory interactions from our in vitro results. To address these issues, formation of EtS and EtG was investigated using recombinant glucuronosyl- and sulfotransferases as well as human liver microsomes and liver cytosol. After respective kinetics had been established, inhibition experiments using quercetin, kaempferol and resveratrol were performed. These polyphenols are subject to extensive glucuronidation and/or sulfonation. EtG and EtS were determined by LC-MS/MS following solid phase extraction for EtG due to severe matrix effects and by direct injection for EtS. All enzymes investigated were involved in the conjugation of ethanol. Maximal EtG and EtS formation rates were observed with HLM and SULT1A1, respectively. All kinetics could best be described by Michaelis-Menten kinetics. Resveratrol was a competitive inhibitor of UGT1A1, UGT1A9 and HLM; quercetin and kaempferol were inhibitors of all transferases under investigation except UGT2B15. Findings for quercetin with regard to UGT2B7 and SULT2A1 and for kaempferol with regard to SULT1E1 and SULT2A1 suggested a mechanism based inhibition. Competitive inhibition of the glucuronidation and sulfonation of ethanol was estimated as weak to negligible and as moderate to weak, respectively. Beside the known polymorphisms of the transferases involved in EtG and EtS formation, prediction of the inhibitory potential indicates that polyphenols may contribute to the variable formation rate of EtG and EtS.

An unnatural death by propan-1-ol and propan-2-ol

A fatality of an inpatient ingesting a disinfectant containing ethanol, propan-1-ol, and propan-2-ol is reported. The alleged survival time was about 1 h. Major findings at autopsy were an extended hemorrhagic lung edema, an edematous brain, and shock kidneys. Concentrations of alcohols and acetone, a major metabolite of propan-2-ol, were determined from body fluids (blood from the heart and the femoral vein, urine, gastric contents) and tissues (brain, muscle, liver, kidneys, lungs) by headspace/gas chromatography using 2-methylpropan-2-ol as the internal standard. All samples investigated were positive for propan-1-ol, propan-2-ol, ethanol, and acetone except stomach contents, where acetone was not detectable. The low concentration of acetone compared to propan-2-ol likely supports the short survival time. The concentration ratios estimated from the results are in accordance with the physico-chemical properties of the particular alcohols, their different affinities towards alcohol dehydrogenase as well as their interdependence during biotransformation. Autopsy did not reveal the cause of death. According to the few published data, blood concentrations of 1.44 and 1.70 mg/g of propan-2-ol and propan-1-ol, respectively, are considered sufficient to have caused the death. This case also points to the need to restrict access to antiseptic solutions containing alcohols in wards with patients at risk.

A potential new metabolite of gamma-hydroxybutyrate: sulfonated gamma-hydroxybutyric acid

Detection of gamma-hydroxybutyric acid (GHB) became crucial in many clinical and forensic settings due to its increasing use for recreational purposes and drug-facilitated sexual assault. Its narrow window of detection of about 3-12 h in urine represents a major problem. Analogous to ethyl glucuronide, the recently identified GHB-glucuronide exhibits a longer window of detection than the parent drug. It appeared reasonable that a sulfonated metabolite of GHB (GHB-SUL) will also be formed. Due to the lack of an appropriate standard, GHB was incubated with a human liver cytosolic fraction to produce GHB-SUL. Following development of a liquid chromatography/tandem mass spectrometry (LC-MS/MS) assay to measure GHB and GHB-SUL, authentic urine samples (n = 5) were tested for GHB-SUL. These investigations revealed detectable signals of both GHB and GHB-SUL, strongly indicating that GHB is not only glucuronidated but also sulfonated. Given that sulfonated metabolites generally have longer half-life times than the corresponding free drugs, GHB-SUL may serve as a biomarker of GHB misuse along with its glucuronide.

[Diuretics and their potential effect on breath-alcohol concentration--a case report]

Many objections were raised to breath-alcohol analysis upon its introduction in the field of traffic law enforcement in Germany, but in the meantime this issue has become less relevant in forensic routine work. In the present case, the defending lawyer claimed that the ethanol concentration in the blood and hence in the breath of his client, which was 0.35 mg/l according to the Dräger Alcotest 7110® Evidential and thus above the legal limit of 0.25 mg/l, had been changed by diuretics taken 4 hours before the breath alcohol test, viz. 10 mg of torasemide, a loop diuretic, and 50 mg of spironolactone, a competitive aldosterone antagonist. According to the literature, the maximum urinary output in healthy subjects within the first 4 hours after 10 mg torasemide was 1450 ml. In patients suffering from heart failure, the urinary volume was reduced by a factor of 2.5-3; after chronic intake of torasemide, water loss did not differ from placebo. Spironolactone, which acts on the distal tubule, has little effect on urinary output. In a publication, the loss of water in excess within 24 hours was 90 ml. Co-administration of 100 mg spironolactone and 20 mg furosemide, which roughly compares to 10 mg torasemide, resulted in a mean urinary volume of 1566 ml within the first 4 hours. In terms of the reported case and provided that no compensatory fluid had been taken, a purely theoretical maximum shift of 0.007 mg/ may occur in the breath-alcohol concentration due to the smaller distribution volume even considering maximum urinary excretion values. On the other hand, already mild levels of dehydration may be associated with negative symptoms affecting driving ability.

Simultaneous quantification of tobacco alkaloids and major phase I metabolites by LC-MS/MS in human tissue

INTRODUCTION

Insurance agencies might request laboratories to differentiate whether a deceased has been a smoker or not to decide about refunding of his nonsmoker rate. In this context, the question on a solid proof of tobacco alkaloids and major metabolites in tissues came up. Currently, an appropriate assay is still lacking to analyze tissue distribution in smokers or nonsmokers. Nicotine (NIC), nornicotine (NNIC), anatabine (ATB), anabasine (ABS), and myosmine (MYO) are naturally occurring alkaloids of the tobacco plant; most important phase I metabolites of NIC are cotinine (COT), norcotinine (NCOT), trans-3'-hydroxycotinine (HCOT), nicotine-N'-oxide (NNO), and cotinine-N-oxide (CNO). An analytical assay for their determination was developed and applied to five randomly selected autopsy cases.

METHODS

Homogenates using 500 mg aliquots of tissue samples were analyzed by liquid chromatography/tandem mass spectrometry following solid phase extraction. The method was validated according to current international guidelines.

RESULTS

NIC, COT, NCOT, ABS, ATB, and HCOT could be detected in all tissues under investigation. Highest NIC concentrations were observed in the lungs, whereas highest COT concentrations have been found in the liver. MYO was not detectable in any of the tissues under investigation.

CONCLUSIONS

The assay is able to adequately separate isobaric analyte pairs such as NIC/ABS/NCOT and HCOT/CNO thus being suitable for the determination of tobacco alkaloids and their phase I metabolites from tissue. More autopsy cases as well as corresponding body fluids and hair samples will be investigated to differentiate smokers from nonsmokers.

Pharmacokinetic interaction of intravenous fentanyl with ketoconazole

Fentanyl is primarily metabolized by CYP3A, but has also been suggested to act as a weak inhibitor of CYP3A. We investigated the influence of CYP3A inhibition by ketoconazole on the pharmacokinetics of intravenously administered fentanyl and the effect of fentanyl on CYP3A activity. A prospective, open-label, randomized, monocentre, crossover study was conducted in 16 healthy volunteers. They received fentanyl alone (5 microgram per kilogram) or fentanyl plus ketoconazole (200 milligram orally B.I.D. over 2 days). Naloxone (2 × 0.2 milligram i.v.) was given simultaneously with fentanyl to mitigate any opioid effect. Midazolam was administered as a CYP3A probe drug. Fentanyl and its metabolites were quantified by LC/MS/MS in blood and urine samples obtained over 24 hour. Exposure of fentanyl (AUC0- ∞ ) was significantly increased to 133% and systemic clearance was reduced to 78% by ketoconazole, norfentanyl formation was significantly delayed and partial metabolic clearance decreased to 18%. Fentanyl had no influence on midazolam exposure and CYP3A activity whereas ketoconazole decreased CYP3A activity to 13%. Although fentanyl N-dealkylation is substantially inhibited by ketoconazole, exposure of fentanyl itself increased by one third only. Clinically fentanyl dosage adjustments may become necessary when ketoconazole or other strong CYP3A inhibitors are given simultaneously. Fentanyl itself does not influence CYP3A activity.

Identification and characterization of sulfonyltransferases catalyzing ethyl sulfate formation and their inhibition by polyphenols

Ethyl sulfate (EtS) is a minor metabolite of ethanol, usually being present along with ethyl glucuronide in both blood and urine. At present, there have been few studies on sulfotransferases (SULTs) catalyzing EtS formation. Moreover, inhibition by nutritional components on EtS formation, e.g., polyphenols that are extensively sulfonated, has not been addressed at all. Firstly, the incubation procedure was optimized with regard to buffer, substrate concentration, and incubation time. Recombinant SULT enzymes including SULT1A1, 1A3, 1B1, 1E1, and 2A1 were screened for their activity towards ethanol; subsequently, respective kinetics was investigated. The inhibitory potential of resveratrol, quercetin, and kaempferol being abundant in beer and wine was studied thereafter. Analysis was performed by liquid chromatography/tandem mass spectrometry (LC-MS/MS) using deuterated EtS as the internal standard. All enzymes are involved in the sulfonation of ethanol; respective kinetics followed the Michaelis-Menten model. Among the five SULTs under investigation, SULT1A1 displayed the highest activity towards ethanol followed by SULT2A1. Polyphenols significantly reduced the formation of EtS. Results revealed multiple SULT isoforms being capable of catalyzing the transfer of a sulfo group to ethanol; nevertheless, the relevance of SULTs' polymorphism on the sulfonation of ethanol needs further appraisal. Nutritional components such as polyphenols effectively inhibit formation of EtS; this observation may partly serve as an explanation of the highly inter-individual variability of EtS findings in both blood and urine.

[In vitro characterization of glucuronosyl- and sulfotransferases involved in the conjugation of ethanol]

Ethyl glucuronide (EtG) and ethyl sulfate (EtS) are minor metabolites of ethanol; for some years, both compounds have been used as direct biomarkers of alcohol consumption in forensic and clinical settings as well as in traffic medicine. Drinking experiments showed individual variations of the formation of EtG and EtS. At present, our knowledge on enzymes involved in the conjugation of ethanol is incomplete and partly inconsistent. The purpose of the present study was to characterize those enzymes that are capable of catalyzing glucuronidation and sulfation of ethanol including some potential inhibitors. Following optimization of incubation conditions, the formation rates of EtG and EtS from ethanol via recombinant glucuronosyltransferases (UGTs, hepatic) and sulfotransferases (SULTs, hepatic, intestinal), the kinetics and the inhibitory potential of polyphenols such as quercetin, kaempferol and resveratrol were determined. Analysis was performed following either solid phase extraction due to severe ion suppression of EtG or direct injection of the EtS-containing incubation mixture by high-pressure liquid chromatography/tandem mass spectrometry. Deuterated analogues were used as internal standards. All UGTs were capable of metabolizing ethanol through glucuronidation; UGT1A9 and UGT2B7 exhibited the highest formation rates. All SULTs showed ethanol-sulfating activity with SULT1A1 being most active. Data for all enzymes could best be described by Michaelis-Menten kinetics. All polyphenols inhibited the conjugation of ethanol except UGT2B 15. Inhibition was reversible and competitive for most enzymes; mechanism-based inhibition was evident for UGT2B7 and SULT2A1 with regard to quercetin and for SULT1E1 with regard to kaempferol. These results suggest an influence on the formation rates of EtG and EtS by common food ingredients beside known polymorphisms of UGT and SULT family members. Further studies should be conducted to achieve a better understanding of the extent and significance of this influence.

Quantitative low-volume assay for simultaneous determination of fentanyl, norfentanyl, and minor metabolites in human plasma and urine by liquid chromatography-tandem mass spectrometry (LC-MS/MS)

A rapid and sensitive liquid chromatography/tandem mass spectrometric (LC-MS/MS) method for simultaneous quantification of fentanyl (F), norfentanyl (NF), despropionylfentanyl (DPF), and hydroxynorfentanyl (OHNF) in human plasma and urine specimens has been developed and validated according to international guidelines. Analytes were extracted from 250-μL plasma or urine by liquid-liquid extraction. OHNF in urine affords a second extraction step and analysis with a different column. Calibration curves in plasma were linear from 0.05-10 ng/mL for F, 0.07-0.5 ng/mL for NF, 0.02-1.0 ng/ml for DPF, and 0.67-3.0 ng/mL for OHNF; in urine, from 0.09-10.0, 0.17-50, 0.08-1.0, and 1.0-5.0 ng/mL for F, NF, DPF, and OHNF, respectively. Analytical bias and intra- and inter-assay imprecision were within ± 15 % of target, except for OHNF in plasma and DPF in urine at the respective lower quality control level. All analytes were stable in processed samples when stored for 24 h at room temperature. Recoveries and process efficiencies were above 82.9 and 75.1 % for all analytes in plasma and urine. The low level of DPF in plasma indicated with a matrix effect of 71.3 % moderate ion suppression, all other analytes in plasma and urine showed no matrix effects. The lower limit of quantification (LOQ) in plasma was 0.05, 0.07, 0.02 and 0.67 ng/mL for F, NF, DPF, and OHNF, respectively. In urine, the LOQ of F, NF, DPF, and OHNF were 0.09, 0.17, 0.08, and 1.28 ng/mL, respectively. This assay has been applied to human specimens collected during a clinical drug-drug interaction study.

Biflavonoide aus Schinus terebinthifolius Raddi (Anacardiaceae)/ Biflavonoids from Schinus terebinthifolius Raddi (Anacardiaceae)

Three biflavonoids together with gallic acid have been isolated for the first time from the drupes of S. terebinthifolius. They have been characterized through chemical and spectral data.

Identification and preliminary characterization of UDP-glucuronosyltransferases catalyzing formation of ethyl glucuronide

Ethyl glucuronide (EtG), a minor metabolite of ethanol, is used as a marker of alcohol consumption in a variety of clinical and forensic settings. At present there are very few studies of UDP-glucuronosyltransferases (UGT), responsible for catalyzing EtG formation, and the possible effect of nutritional components, e.g. flavonoids, which are extensively glucuronidated, on EtG formation has not been addressed at all. The following incubation conditions were optimized with regard to previously published conditions: buffer, substrate concentration, and incubation time. Isolation of EtG from the incubation mixture was also optimized. Recombinant UGT enzymes (UGT1A1, 1A3, 1A4, 1A6, 1A9, 2B7, 2B10, 2B15) were screened for their activity towards ethanol, and kinetic data were then established for all enzymes. It was decided to study the effect of the flavonoids quercetin and kaempferol on glucuronidation of ethanol. Isolation was by solid-phase extraction (SPE) to minimize matrix effects. Analysis was performed by liquid chromatography-tandem mass spectrometry (LC-MS-MS), with EtG-d5 as the internal standard. SPE was vital to avoid severe ion suppression after direct injection of the incubation solution. EtG formation was observed for all enzymes under investigation; their kinetics followed the Michaelis-Menten model, meaning the maximum reaction rate achieved at saturating substrate concentrations (V(max)) and the substrate concentration at which the reaction rate is half of V(max) (Michaelis-Menten constant, K(m)) could be calculated. The highest rate of glucuronidation was observed with UGT1A9 and 2B7. After co-incubation with both flavonoids, formation of EtG was significantly reduced for all enzymes except for UGT2B15, whose activity did not seem to be affected. Results reveal that multiple UGT isoforms are capable of catalyzing glucuronidation of ethanol; nevertheless, the effect of UGT polymorphism on glucuronidation of ethanol needs further study. Formation of EtG is inhibited by the flavonoids under investigation. Obviously, nutritional components affect conversion of ethanol to EtG. This observation may serve as a partial explanation of its variable formation in man.

An in vitro experiment on the interaction of charcoal or wheat bran with 11-nor-9-carboxy-Δ(9)-tetrahydrocannabinol and its glucuronide

The rather long yet variable terminal half-lives and detection times since last use of urinary cannabinoids may partly be attributed to their enterohepatic circulation which generally can be interrupted or restricted by chemical adsorbents. Therefore, an in vitro experiment was performed to study the adsorption/binding of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THC-COOH) and its glucuronide to activated charcoal and wheat bran; remaining concentrations were determined by liquid chromatography/tandem mass spectrometry. Adsorption/binding of 1,000 ng/mL of free or conjugated THC-COOH was complete using as little as 5 mg of charcoal whereas adsorption/binding to wheat bran increased with increasing amounts. Taking of remedies affecting enterohepatic recycling of THC-COOH and its glucuronide may challenge interpretation of cannabinoid concentrations used to detect or assess frequency of drug use or the time since last drug consumption.

[Phentermine--a "weighty" or a dangerous substance?]

According to international surveys, the appetite suppressant phentermine has frequently been seized although its approval has been withdrawn in Germany. Phentermine is an isomer of methamphetamine though is not optically active such as e. g. amphetamine. The drug acts as a potent substrate at the norepinephrine transporter simultaneously promoting its release; it has a weaker activity at the dopamine transporter whereas its activity towards the serotonin transporter is negligible. Overall, its pharmacological action is comparable to that of amphetamine albeit less strong. Due to its declining effect with time and its addiction potential it has been recommended that phentermine should be used for a few weeks only. Phentermine hydrochloride is a readily soluble salt; absorption of the resinate compound is considerably slower. The drug is not extensively biotransformed; p- and N-hydroxyphentermine are the primary metabolites also being excreted as glucuronide conjugates. Gas chromatographic techniques to identify and to quantify phentermine in biological specimens are applicable following derivatization; however, liquid chromatography coupled to mass spectrometry is currently preferred for analysis of urine, serum or hair. Short-term clinical studies having been performed in the 80s and 90s revealed no serious harmful side effects. However, there are case reports proposing that phentermine usage might be associated with severe health risks due to hypertension, vasoconstriction and vasculopathy; in some individuals, mental illness had been observed. Apart from the legal consequences following purchase of drugs that have been withdrawn its user will simultaneously run serious and unpredictable health risks.

Comparison of direct and indirect alcohol markers with PEth in blood and urine in alcohol dependent inpatients during detoxication

The importance of direct and indirect alcohol markers to evaluate alcohol consumption in clinical and forensic settings is increasingly recognized. While some markers are used to prove abstinence from ethanol, other markers are suitable for detection of alcohol misuse. Phosphatidyl ethanol (PEth) is ranked among the latter. There is only little information about the correlation between PEth and other currently used markers (ethyl glucuronide, ethyl sulfate, carbohydrate deficient transferrin, gamma-glutamyl transpeptidase, and methanol) and about their decline during detoxification. To get more information, 18 alcohol-dependent patients in withdrawal therapy were monitored for these parameters in blood and urine for up to 19 days. There was no correlation between the different markers. PEth showed a rapid decrease at the beginning of the intervention, a slow decline after the first few days, and could still be detected after 19 days of abstinence from ethanol.