Population pharmacokinetics of multiple alcohol intake in humans

Back to the future: Retrograde alcohol calculations an uncertain science

Retrograde extrapolations, known as back calculations are widely used in forensic toxicology to estimate the blood alcohol concentration of an individual at some prior time. In the UK guidelines have been issued by the United Kingdom and Ireland Association of Forensic Toxicologists) and the Organization of Scientific Area Committees (OSAC) for Forensic Science. However, these guidelines are not fully agreed and open tointerpretation. Alcohol elimination rates have been discussed in numerous publications since Widmark's original data was published. The current guidance from UKIAFT, is to report the most likely back calculated result together with a range of results based on the 95% confidence limit elimination rates (9 to 29 mg/100 mL/hour).The Divisional Court, upheld by the House of Lords, ruled that in order to convict someone for being over the prescribed limit on the basis of any back calculation, the case must be proven beyond reasonable doubt. A 99.73% confidence interval increased to 3 standard deviations at the lower end would provide a greater factual basis for the court and cover alarger proportion of the population, this can be achieved by increasing the elimination range to 8 to 29 mg/100 mL/hour. Retrograde extrapolations also rely on the subject being post absorptive at the prior time. In the UK, back calculations are validif the subject has not eaten or consumed alcohol withinonehour ofthe back calculation time. Where the subject has eatenprior to the back calculation, experts are instructed to consider whether the back calculation is applicable. In Germany and the United States back calculations are not permitted to a time within 2 h after last drink consumed. The 2 h limit would better meet the highest standard of 'beyond reasonable doubt' burden of proof, and should be used. These proposed changes would decrease the uncertainty associated with retrograde calculations carried out by UK toxicologists.

Correlation between blood alcohol concentration (BAC), breath alcohol concentration (BrAC) and psychomotor evaluation in a clinical monitored study of alcohol intake in Brazil

BACKGROUND

Policies that establish maximum blood alcohol concentrations (BACs) or breath alcohol concentration (BrACs) for drivers while driving can reduce traffic accidents by approximately 20%. In Brazil, the National Transit Council (CONTRAN) considers positive BAC and/or BrAC tests or signs of psychomotor capacity alterations as evaluated by a police authority to be an administrative infraction or even a crime. The observed clinical symptoms of alcohol intoxication based on a subject's appearance may not necessarily reflect the quantified BAC and/or BrAC. This study compared the clinical symptoms identified by a medical authority (M) and a non-medical authority (NM) with BAC and BrAC measurements.

METHODS

Brazilian health volunteers (n = 15) drank ethanol (40% v/v) and, at scheduled times, the subjects underwent blood draws for BAC analysis, were tested for BrAC analysis, and underwent psychomotor alteration assessments performed by M and NM.

RESULTS

Concentration-time profiles of the BACs and BrACs of the volunteer subjects were generated. The BAC values reached a peak at 60 min and subsequently decreased with time. The average BrAC values decreased with time after ingestion. During the evaluations, M was able to identify a lack of static equilibrium until 240 min and a lack of dynamic equilibrium until 120 min. A lack of upper limb motor coordination was observed until 90 min, and a lack of coordination in the lower limbs was observed only during the first hour. Regarding the tests performed by NM, the signs related to the subjects' appearances were observed more frequently, until 60 min. The other analyzed symptoms were not identified. Naturally, the signs reported by both M and NM disappeared with time.

CONCLUSION

The evaluations of psychomotor changes performed by Brazilian M were superior to those performed by NM. However, independent of the examiner, at the alcohol concentrations reached in this study, the psychomotor alteration evaluations were ineffective compared with the BAC and BrAC results.

A Bayesian Approach for Population Pharmacokinetic Modeling of Alcohol in Japanese Individuals

Background

Blood alcohol concentration data that were previously obtained from 34 healthy Japanese subjects with limited sampling times were reanalyzed. Characteristics of the data were that the concentrations were obtained from only the early part of the time-concentration curve.

Objective

To explore significant covariates for the population pharmacokinetic analysis of alcohol by incorporating external data using a Bayesian method, and to estimate effects of the covariates.

Methods

The data were analyzed using a Markov chain Monte Carlo Bayesian estimation with NONMEM 7.3 (ICON Clinical Research LLC, North Wales, Pennsylvania). Informative priors were obtained from the external study.

Results

A 1-compartment model with Michaelis-Menten elimination was used. The typical value for the apparent volume of distribution was 49.3 L at the age of 29.4 years. Volume of distribution was estimated to be 20.4 L smaller in subjects with the ALDH2*1/*2 genotype than in subjects with the ALDH2*1/*1 genotype.

Conclusions

A population pharmacokinetic model for alcohol was updated. A Bayesian approach allowed interpretation of significant covariate relationships, even if the current dataset is not informative about all parameters. This is the first study reporting an estimate of the effect of the ALDH2 genotype in a PPK model.

Ethanol pharmacokinetics in neonates and infants

Introduction

Ethanol has been used for years in neonatal and infant liquid medications, yet the pharmacokinetics, pharmacodynamics, and safety of ethanol in this vulnerable population have not been well characterized. The purpose of this review is to raise awareness of ethanol use as an excipient in neonatal and infant medications and to provide insight, based on the available evidence, into clearance rates of ethanol in babies. We also discuss ethanol pharmacokinetics in adults, theoretical pharmacokinetic changes in neonates and infants as it may apply to ethanol disposition, and case reports involving ethanol exposure in neonates and infants.

Materials and methods

This study was a narrative review in which relevant papers were selected using databases and scientific search engines such as PubMed with the key words ethanol, infant, and newborninfant.

Results

It remains unclear what ethanol exposure is safe for neonates and infants. The Food and Drug Administration and American Academy of Pediatrics have both taken action, by either setting limits of ethanol content in over-the-counter medications or by recommending restricted exposure to ethanol-containing pediatric formulations.

Conclusions

Until the short- and long-term health effects of chronic ethanol administration can be further characterized, ethanol-containing medications should be used with caution.

Ethanol Analysis in Postmortem and Human Performance Forensic Toxicology Cases

Ethanol analysis is probably the most common procedure performed in forensic and analytical toxicology laboratories worldwide. Ethanol poisoning is very important in both clinical and forensic investigations. In clinical evaluations, measuring the ethanol concentration is necessary for the timely and appropriate delivery of care to patients who may experience discomfort or life threatening ethanolic overdose or mixed ethanol-drug intoxication. In forensic toxicology investigations, ethanol is routinely measured in both human performance forensic toxicology cases such as drug-facilitated crimes and driving-under-the-influence cases, as well as in postmortem forensic toxicology cases. This review presents information regarding the most commonly analyzed biological specimens used in alcohol analysis including, among others, blood, breath, urine, oral fluid, and vitreous humor. Additionally, it presents the various chemical, biochemical, gas chromatographic, and breath testing techniques commonly employed in ethanol analysis and considers the main advantages and disadvantages of each. Finally, a brief discussion of quality assurance in alcohol analysis is presented.