Evaluating alleged drinking after driving--the hip-flask defence. Part 1. Double blood samples and urine-to-blood alcohol relationship

"Not everything that can be counted counts" in ethanol toxicological results: an antemortem and postmortem technical interpretation focusing on driving under the influence

Ethanol blood analysis is the most common request in forensic toxicology, and some studies point to positive results in approximately one-third of all unnatural deaths. However, distinguishing sober deaths from drunk deaths is not as simple as it may seem. This technical, clinical, and forensic interpretation is proposed to interpret the ethanol toxicological results, discussing several artefacts and pitfalls that must be considered, namely focusing on driving under the influence. This work is presented with a practical and objective approach, aiming to alleviate the complexities associated with clinical, physiological, pathophysiological, and toxicological aspects to enhance comprehension, practicality, and applicability of its content, especially to courts. Particularly the physical integrity of the body, the postmortem interval, putrefactive signs, anatomic place of blood collection, alternative samples such as vitreous humour and urine, the possibility of postmortem redistribution, the inclusion of preservatives in containers, and optimal temperature conditions of shipment are among some of the aspects to pay attention. Although several biomarkers related to postmortem microbial ethanol production have been proposed, their translation into forensic routine is slow to be implemented due to the uncertainties of their application and analytical difficulties. Specifically, in the interpretation of ethanol toxicological results, "not everything that can be counted counts and not everything that counts can be counted" (attributed to Albert Einstein).

Mathematical modeling of the kinetics of a single intake of ethanol

The aim of the study is to construct a kinetic equation of zero-order ethanol elimination with first-order absorption, taking into account the presystemic metabolism of ethanol, with the possibility of determining the errors in estimating the parameters of the model, as well as the implementation of the model in the format of a computer program. Analytical mathematical modeling of the kinetics of a single oral intake of ethanol has been performed. A mathematical model of the kinetics of a single intake of ethanol with its zero-order elimination, absorption and first-order presystemic metabolism has been developed. A method is proposed for estimating the limiting absolute errors of the kinetic parameters of the constructed model based on the summation of the partial contributions of the initial physical quantities. The complex of the developed computational procedures is implemented in the format of the «Alcohol Calculator V 1.0» computer program. The conclusion is made about the expediency of using the developed information and computing technology in the forensic medical expert assessment of acute alcohol intoxication.

Mathematical modeling of the kinetics of a single intake of ethanol

The aim of the study is to construct a kinetic equation of zero-order ethanol elimination with first-order absorption, taking into account the presystemic metabolism of ethanol, with the possibility of determining the errors in estimating the parameters of the model, as well as the implementation of the model in the format of a computer program. Analytical mathematical modeling of the kinetics of a single oral intake of ethanol has been performed. A mathematical model of the kinetics of a single intake of ethanol with its zero-order elimination, absorption and first-order presystemic metabolism has been developed. A method is proposed for estimating the limiting absolute errors of the kinetic parameters of the constructed model based on the summation of the partial contributions of the initial physical quantities. The complex of the developed computational procedures is implemented in the format of the «Alcohol Calculator V 1.0» computer program. The conclusion is made about the expediency of using the developed information and computing technology in the forensic medical expert assessment of acute alcohol intoxication.

Hip-flask defense: An experimental study in the Hungarian population

Toxicology tests and medical expert opinions are part of routine work in drunk driving cases in both domestic and international practice. The greatest challenge to forming an opinion is that the perpetrator claims to have consumed alcohol after the act of driving. To determine the time of consumption, it is essential to establish whether the alcohol in the body was in the absorption phase or in the elimination phase when the sample was collected. In domestic practice, breath alcohol content can be measured several times, two blood samples can be collected, and both blood and urine samples can be taken almost simultaneously. A recent Swedish study showed that taking a single blood sample and two urine samples allows for a more accurate examination of consumption after the fact. This study aimed to examine the applicability of such model to the domestic environment. We conducted a controlled drinking experiment involving 15 Hungarian casual drinker volunteers aged 18-25 years who consumed different amounts of alcohol at specified times while providing regular breath alcohol measurements as well as blood and urine samples. These measurement results provided accurate information about the changes in alcohol metabolism compared to the time of drinking and allowed us to draw the necessary conclusions, offering further evidence that alcohol metabolism can vary significantly between different ethnic groups. The results showed that the absorption and excretion of ethyl alcohol in the volunteers were much faster than those in the current Hungarian standards used in practice. In conclusion, the comparison of blood and urine samples collected between 60 min and 120 min cannot be considered suitable for establishing the fact of drinking after driving in Hungarian practice, and a local model is needed.

Evaluating the hip-flask defence using analytical data from ethanol and ethyl glucuronide. A comparison of two models

AIM

Claimed intake of alcohol after a traffic incident, called the hip-flask defence, can be objectively assessed by different methods. One of them is the use of two consecutive ethanol concentrations in urine and the ratio between ethanol concentrations in urine and blood. Another one is the concentrations of ethyl glucuronide (EtG) and ethyl sulphate (EtS) in blood and their ratio to ethanol. The experimental basis for both these models is from single dose studies only. The aim of this study was therefore to describe the kinetics of ethanol, EtG and EtS after ingestion of two repeated doses of ethanol and to investigate the usefulness of the different models for the assessment of the hip-flask defence.

METHODS

Thirty-five subjects ingested a first dose of 0.51 g of ethanol per kilo body weight, and two hours later a second dose (the hip-flask drink) of 0.25, 0.51 or 0.85 g of ethanol per kilo body weight. Ten urine and 17 blood samples were collected and analysed for ethanol, EtG and EtS using fully validated methods. It was investigated if all subjects fulfilled the criteria for recent drinking, according to the two different models, when using the samples collected 180-240 minutes after start of first dose drinking. According to the first model, increase in urinary ethanol concentrations and a ratio UAC/BAC below 1.3 indicated recent drinking. According to the second model, increase in blood EtG concentrations and a ratio ethanol (g/kg)/EtG (mg/L) above 1 indicated recent drinking.

RESULTS

All subjects in the high dose group fulfilled all criteria for recent drinking. One subject in the medium dose group and nine subjects in the low dose group failed to show increasing UAC and/or a UAC/BAC ratio below 1.3. One subject in the low dose group failed to show increasing concentrations of blood EtG, but all subjects showed a ratio ethanol/EtG above 1.

CONCLUSIONS

The present study showed, by the use of experimental data, that both two models used to investigate the hip-flask defence can be used, but only when the hip-flask dose is sufficiently high.

What the lab can and cannot do: clinical interpretation of drug testing results

Urine drug testing is one of the objective tools available to assess adherence. To monitor adherence, quantitative urinary results can assist in differentiating "new" drug use from "previous" (historical) drug use. "Spikes" in urinary concentration can assist in identifying patterns of drug use. Coupled chromatographic-mass spectrometric methods are capable of identifying very small amounts of analyte and can make clinical interpretation rather challenging, specifically for drugs that have a longer half-life. Polypharmacy is common in treatment and rehabilitation programs because of co-morbidities. Medications prescribed for comorbidities can cause drug-drug interaction and phenoconversion of genotypic extensive metabolizers into phenotypic poor metabolizers of the treatment drug. This can have significant impact on both pharmacokinetic (PK) and pharmacodynamic properties of the treatment drug. Therapeutic drug monitoring (TDM) coupled with PKs can assist in interpreting the effects of phenoconversion. TDM-PKs reflects the cumulative effects of pathophysiological changes in the patient as well as drug-drug interactions and should be considered for treatment medications/drugs used to manage pain and treat substance abuse. Since only a few enzyme immunoassays for TDM are available, this is a unique opportunity for clinical laboratory scientists to develop TDM-PK protocols that can have a significant impact on patient care and personalized medicine. Interpretation of drug screening results should be done with caution while considering pharmacological properties and the presence or absence of the parent drug and its metabolites. The objective of this manuscript is to review and address the variables that influence interpretation of different drugs analyzed from a rehabilitation and treatment programs perspective.

Evaluation of the hip-flask defence by determination of ethyl glucuronide and ethyl sulphate concentrations in blood

INTRODUCTION

The hip-flask defence (i.e. claiming ethanol intake after an incident) is difficult to refute by the use of ethanol analyses alone, as these may show decreasing concentrations shortly after intake of alcohol. The non-oxidative metabolites of ethanol, ethyl glucuronide (EtG) and ethyl sulphate (EtS) have a different pharmacokinetic profile, with peak concentrations in blood around 4h after intake. The aim of this study was to describe a method for using EtG-analysis for the purpose of estimating the time point of ethanol intake and to report cases in which this method is used.

METHODS

Previously published studies are summarised. Also, in expert witness cases where the hip-flask defence is claimed, EtG and EtS were analysed in selected cases. Twelve such cases are reported.

RESULTS

In previous studies, about 70 healthy volunteers have been included in different kinetic studies, demonstrating maximal individual concentrations of EtG always below 0.5 mg/L after 1 h, below 1 mg/L after 2 h and somewhat above 1 mg/L 4 h after a moderate alcohol intake (up to 80 grams of ethanol). Twelve cases are reported in the present study, where the suspect claimed no alcohol intake before driving, only intake after driving. In all 12 cases, ethanol concentration was lower in the second sample (taken approximately 30 min after the first). The median EtG concentration in the first sample was 4.13 mg/L (range 2.0-7.4) and 4.34 mg/L (range 2.1-7.2) in the second sample. One case showed an increase in EtG concentrations of 15% from first to second sample (the time difference between the samples was 32 min, with the first sample taken 41 min after driving). For the remainder of the cases, EtG concentrations were relatively stable.

CONCLUSIONS

In all the presented cases, the levels of EtG were substantially higher than what would be expected only about 1-2h after a very recent alcohol intake. The relatively stable concentrations between the first and second sample also indicated that the high EtG concentrations were not caused by a rapid formation after a recent intake, as this would have demonstrated increasing concentrations over a time period of 30 min. In conclusion, EtG and EtS in blood could be a helpful tool in assessment of the hip-flask defence, in cases where the detected ethanol is claimed to be caused solely by a single intake after driving.

A pharmacokinetic study of ethyl glucuronide in blood and urine: Applications to forensic toxicology

This pharmacokinetic study investigated the kinetics of ethanol and its metabolite ethyl glucuronide (EtG) in blood and urine during the whole time course of absorption and elimination. There are few previous studies on the kinetics of EtG in blood, and we wanted to evaluate whether such knowledge could yield valuable information regarding the time of ethanol ingestion in forensic cases, such as, for instance, drunk driving. Ten male volunteers consumed ethanol at a fixed dose of 0.5 g/kg body weight in a fasted state. Blood samples were collected for 14 h and urine samples were collected for 45-50 h after the start of drinking. EtG reached its maximum concentration (C(max)) in blood after a median of 4 h (range 3.5-5), a median of 3 h (range 2-4.5) after C(max) for ethanol. The ethanol-to-EtG ratios in blood (ethanol in g/L, EtG in mg/L) were >1 only for the first median 3.5 h (range 2.5-3.5) after drinking. EtG elimination occurred with a median half-life of 2.2 h (range 1.7-3.1 h), and the renal clearance was 8.32 L/h (median, range 5.25-20.86). The concentrations of EtG were always much higher in urine than in blood. The total amount of EtG excreted in the urine was median 30 mg (range 21.5-39.7), representing 0.017% (median, range 0.013-0.022) of the ethanol given, on a molar basis. The information from the present study may be a valuable supplement to determine the time of ethanol ingestion. For this purpose, two subsequent increasing EtG values and a high ethanol-to-EtG ratio in blood would support information of recent drinking.

Inconsistencies Between Actual and Estimated Blood Alcohol Concentrations in a Field Study of College Students: Do Students Really Know How Much They Drink?

BACKGROUND

Alcohol use by college students is commonly measured through the use of surveys. The validity of such data hinge on the assumption that students are aware of how much alcohol they actually consume. Recent studies call this assumption into question. Students tend to overestimate the appropriate sizes of standard drinks, suggesting that they might underestimate how much alcohol they consume. If this is true, then students' actual blood alcohol concentrations (BACs) should be higher than BACs estimated based on self-report data. The present study examined this issue

METHODS

Breathalyzer readings and self-reported drinking data were collected from 152 college students during the fall of 2004. Estimated BACs were calculated by means of a standard formula, and the relation between actual and estimated BACs was examined. Factors contributing to discrepancies between the two values were identified

RESULTS

Estimated BAC levels were significantly higher, not lower, than breath BAC measures. The accuracy of estimated BACs decreased as the number of drinks and amount of time spent drinking increased. Being male and drinking only beer predicted greater accuracy of estimated BACs

CONCLUSIONS

Although laboratory data suggest that students underestimate how much they drink, the hypothesis was not supported by data collected in the field. It appears that students might actually overestimate rather than underestimate their levels of consumption when surveyed in the midst of a night of drinking. The findings corroborate observations made by other researchers and suggest that the findings of laboratory studies on college drinking do not necessarily extend to real-world settings.

Urine as a Biological Specimen for Forensic Analysis of Alcohol and Variability in the Urine-to-Blood Relationship

This article concerns the use of urine as a biological specimen for determination of alcohol in clinical and forensic toxicology and discusses factors that might influence variability in the urine/blood concentration ratio of alcohol. A large number of human drinking experiments were conducted to determine the time course of urine-alcohol concentrations (UAC) in relation to blood-alcohol concentrations (BAC). The UAC and BAC curves were shifted in time and the BAC curve always began to decrease before the UAC started to decline. During the early absorption phase the UAC/BAC ratio was less than unity, whereas in the late absorption/distribution period the ratio was between 1.0-1.2. On reaching the post-absorptive phase, the UAC always exceeded BAC and UAC/BAC ratios averaged 1.3-1.4, increasing appreciably as BAC decreased towards zero. Alcohol-induced diuresis was most pronounced during the rising portion of the BAC curve and near to the peak value. After about 2 hours post-drinking, the production rate of urine diminished to the pre-drinking rate of about 0.5-1 mL/min. Drinking water during the post-absorptive phase of the alcohol curve produced dilute urine, as reflected in lower creatinine content and osmolality, although the concentration of ethanol remained unchanged. After subjects drank a moderate dose of ethanol (0.54-0.85 g/kg) about 2% of the dose was recoverable in the urine after 7 hours. Ethyl glucuronide, a minor metabolite of ethanol, was measured in urine samples from drunk drivers. The UAC/BAC ratio of ethanol in drunk drivers did not depend on the creatinine content of the urine and therefore the relative dilution of the specimens. When alcohol-free urine was spiked with glucose and infected with the yeast species Candida albicans, ethanol was produced by fermentation after approximately 24 hours storage at room temperature. This post-sampling synthesis of ethanol was prevented by sodium fluoride (1% weight by volume) in the urine tubes or by keeping the specimens in the cold (4 degrees C). The UAC and BAC were highly correlated (r > 0.95) in drunk drivers and in autopsy cases, although the residual standard deviations were appreciable. This speaks against attempting to estimate BAC indirectly from UAC in any individual case. The UAC/BAC ratio and the change in UAC between two successive voids can help to resolve whether a large amount of alcohol had recently been consumed. This information is useful to support or challenge allegations of drinking alcohol after driving, which has become known as the hip-flask defence.

Highly sensitive gas chromatographic determination of ethanol in human urine samples

In order to evaluate recent alcohol consumption, a very sensitive and specific gas chromatographic method for ethanol determination in human urine samples was developed. The non-invasive method was performed without any pretreatment and carried out on a Stabilwax capillary column, 30 m x 0.53 mm x 1.0 microm film thickness. Helium was used as carrier gas with a constant inlet pressure of 27.72 kPa (0.277 bar) and a flame ionization detector (FID). Quantification was performed with the use of acetonitrile as an internal standard (IS). The calibration curve was linear throughout the concentration range from 0.5 to 500 mg/l. The calculated intra- and inter-day coefficients of variation were below 8%. A clear chromatographic separation of ethanol from methanol, acetone, 1-propanol and 2-propanol was achieved.