The calculation of blood ethanol concentrations in males and females

Ethanol elimination rates in men and women in consideration of the calculated liver weight

The purpose of the study was to examine gender differences on the pharmacokinetics of ethanol. Sixty-eight healthy men and 64 healthy women with normal body mass indexes received between 0.79 and 0.95 g ethanol/kg body weight in the form of their choice after they had eaten a "typical" breakfast. The aimed concentration for both genders was a blood alcohol concentration C(0) of 0.104 g/dl. Blood samples in the elimination phase were taken in 10- to 20-min intervals beginning after completion of absorption. The maximum blood ethanol concentration was 0.0819+/-0.0184 g/dl for women and 0.0841+/-0.0155 g/dl for men. The hourly ethanol elimination rate, calculated over a linear function, in blood of 0.0179+/-0.0030 g/dl/h in women was significantly higher than the 0.0159+/-0.0029 g/dl/h for men (P<.0001). In relation to the liver weight, the hourly elimination rates were 5.008+/-0.678 g/kg liver/h for women and 4.854+/-0.659 g/kg liver/h for men, and were not statistically significant. The different liver masses as calculated in relation to the distribution volume account for the differing ethanol elimination rates between men and women.

Body shape and composition in HIV-infected women: an urban cohort

OBJECTIVES

Alterations in body shape and composition are associated with HIV/AIDS. Wasting remains prevalent; increasingly, lipodystrophy is reported. Obesity is also epidemic in the USA. In this study, we sought to characterize the body changes reported by women attending a US urban clinic, and to evaluate contributing factors using inexpensive methods that are readily available in clinical practice.

METHODS

In an urban Maryland clinic, a cross-section of HIV-infected women were evaluated by self report, anthropomorphic measurements, bioelectric impedance analysis (BIA) and chart review; they were categorized as no change, lipodystrophy, weight loss/wasting or weight gain/obesity.

RESULTS

One hundred and sixty-one women were evaluated: 144 (89%) were African-American; 100 (62%) had used intravenous drugs and 40 (25%) were actively injecting drugs, while 39 (24%) smoked crack. Ninety-five (59%) were on highly active antiretroviral therapy (HAART) for a median period of 11.7 months [interquartile range (IQR)=4.5-24.2]. Since starting current HAART or in the previous year, 12 (7.4%) reported lipodystrophy changes, 85 (52.8%) weight gain, 27 (16.8%) overall weight loss, and 37 (23.0%) no change. Lipodystrophy was associated with higher CD4 percentage (P=0.03), lower frequency of crack use (P=0.04) and higher educational level (P=0.03). Weight loss correlated with longer duration of infection (P=0.01), select BIA results and increased rate of crack use (P=0.005). Weight gain was associated with higher fat mass (P=0.005), higher peak viral load (P=0.02), and lower rate of intravenous drug use (P=0.03).

CONCLUSIONS

Self-reported changes in body shape were common. Obesity and complications of illicit drug use were more prevalent than lipodystrophy in this inner-city population of HIV-positive women.

Widmark factors for local Chinese in Hong Kong

The Widmark formula has been widely adopted in forensic applications to drink driving cases for the last 70 years. It is known that the amount of alcohol consumed and the body weight of the drinkers are important information for the estimation of blood alcohol concentration (BAC). However, the direct application of the Widmark factors derived from Caucasian to the calculation of BAC for the Chinese population often encounters serious challenges. Owing to this inherent weakness, a thorough analysis to determine the theoretical Widmark factors for the Chinese population, r(0) at the start of drinking and the practical factors, r(peak), at peak BAC was conducted. In the present study, other factors such as gender, stomach condition and other physiological conditions are taken into account. The determined theoretical Widmark factors, r(0,) for local Chinese male and female are 0.68 and 0.59 (with BAC in the units of weight/volume), respectively, demonstrating the applicability of the Widmark formula to the Chinese population. The practical factors at peak BAC, r(peak), were also determined to serve the forensic purpose of refuting the "hip-flask" defence in drink driving cases. Findings show that gender and stomach condition are the key factors that could statistically explain the variability of both r(0) and r(peak).

A fatal case of pure ethanol ingestion

An adult male was found dead in a car with two empty bottles (500 ml x 2) labeled dehydrated ethanol (>99.5%, v/v). At autopsy, extensive pancreatic necrosis with severe hemorrhage was observed. High concentrations of ethanol were detected in blood (8.14 mg/ml), urine (8.12 mg/ml) and tissue specimens. The cause of death was determined to be an acute alcohol intoxication caused by ingesting approximately 1l dehydrated ethanol.

Role of variability in explaining ethanol pharmacokinetics: research and forensic applications

Variability in the rate and extent of absorption, distribution and elimination of ethanol has important ramifications in clinical and legal medicine. The speed of absorption of ethanol from the gut depends on time of day, drinking pattern, dosage form, concentration of ethanol in the beverage, and particularly the fed or fasting state of the individual. During the absorption phase, a concentration gradient exists between the stomach, portal vein and the peripheral venous circulation. First-pass metabolism and bioavailability are difficult to assess because of dose-, time- and flow-dependent kinetics. Ethanol is transported by the bloodstream to all parts of the body. The rate of equilibration is governed by the ratio of blood flow to tissue mass. Arterial and venous concentrations differ as a function of time after drinking. Ethanol has low solubility in lipids and does not bind to plasma proteins, so volume of distribution is closely related to the amount of water in the body, contributing to sex- and age-related differences in disposition. The bulk of ethanol ingested (95-98%) is metabolised and the remainder is excreted in breath, urine and sweat. The rate-limiting step in oxidation is conversion of ethanol into acetaldehyde by cytosolic alcohol dehydrogenase (ADH), which has a low Michaelis-Menten constant (Km) of 0.05-0.1 g/L. Moreover, this enzyme displays polymorphism, which accounts for racial and ethnic variations in pharmacokinetics. When a moderate dose is ingested, zero-order elimination operates for a large part of the blood-concentration time course, since ADH quickly becomes saturated. Another ethanol-metabolising enzyme, cytochrome P450 2E1, has a higher Km (0.5-0.8 g/L) and is also inducible, so that the clearance of ethanol is increased in heavy drinkers. Study design influences variability in blood ethanol pharmacokinetics. Oral or intravenous administration, or fed or fasted state, might require different pharmacokinetic models. Recent work supports the need for multicompartment models to describe the disposition of ethanol instead of the traditional one-compartment model with zero-order elimination. Moreover, appropriate statistical analysis is needed to isolate between- and within-subject components of variation. Samples at low blood ethanol concentrations improve the estimation of parameters and reduce variability. Variability in ethanol pharmacokinetics stems from a combination of both genetic and environmental factors, and also from the nonlinear nature of ethanol disposition, experimental design, subject selection strategy and dose dependency. More work is needed to document variability in ethanol pharmacokinetics in real-world situations.

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

This two-part article examines the strengths and weaknesses of various ways of investigating claims of drinking alcohol after driving, commonly known as the hip-flask or glove-compartment defence. In many countries the onus of proof in hip-flask cases rests on the prosecution. With good co-operation from the police and timely sampling of body fluids, such as blood and urine for forensic analysis of ethanol, useful evidence can be mustered to support or challenge the truthfulness of alleged drinking after driving. The person's blood-alcohol concentration (BAC) can be compared with values expected on the basis of the amount of alcohol consumed after driving, according to theoretical Widmark calculations. The actual BAC measured is then adjusted for the additional amount of alcohol consumed in the after-drink. Double blood samples, that is, taking two specimens of venous blood about 30-60 minutes apart and looking at the magnitude and direction of change in BAC provides little or no more information than a single blood specimen. However, the relationship between alcohol in blood and urine is very useful in hip-flask cases whereby the concentration expected in the primary urine is compared with the concentration in the bladder urine voided. The concentration of alcohol determined in a second urine sample collected 30-60 min later gives supporting evidence in hip-flask cases. A graphical method, which entails plotting ethanol concentrations in blood and urine as a function of time provides a robust and practical way to investigate hip-flask defences. In the second part of the review, congener analysis is presented, which entails comparing the concentrations of n-propanol, isobutanol and occasionally other congeners in the alcoholic beverage allegedly consumed after driving with the volatiles present in the suspect's blood and urine determined by headspace gas chromatography.