Application of a three-compartment model to a study of the effects of sex, alcohol dose and concentration, exercise and food consumption on the pharmacokinetics of ethanol in healthy volunteers

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.

Population pharmacokinetics of multiple alcohol intake in humans

The objective of this study was to determine population-based pharmacokinetics parameters for ethanol following multiple intake and to identify the factors influencing the pharmacokinetics. Three different solutions of alcoholic liquor (ethanol 55.39 ± 0.45 g) with different dissolved oxygen concentrations were administered, and blood alcohol concentration was determined in 59 healthy subjects using a breath analyzer. Samples (n = 2955) were collected at various time points. Population pharmacokinetic modeling was performed to describe the pharmacokinetics of ethanol. The influence of individuals' demography and dissolved oxygen concentration was investigated, and Visual Predictive Check and bootstrapping were conducted for internal evaluation. The developed model was used to perform simulations to visualize the effects of covariates on individuals. A one-compartment model with Michaelis-Menten elimination kinetics described the multiple ethanol intake data. Population pharmacokinetic estimates of V(max) and K(m) were 3.256 mmol min(-1) and 0.8183 mmol L(-1), respectively. V(d)/F was estimated to be 77.0 L, and K(a) was 0.0767 min(-1). Body weight, age, and the dissolved oxygen concentration were confirmed to be significant covariates. The mean estimates from the developed population pharmacokinetic model were very similar to those from 500 bootstrap samples, and Visual Predictive Check showed that approximately 94% of the observed data fit well within the 5th-95th percentile. A one-compartment model with nonlinear elimination kinetics for multiple ethanol intake was developed and the significant covariates were determined. The robustness of the developed model was evaluated by bootstrap and Visual Predictive Check. The final model and implanted covariates explained well the variability and underlying mechanism of ethanol PK.

The relationship between alcohol elimination rate and increasing blood alcohol concentration—Calculated from two consecutive blood specimens

In the period 1991-2005, a blood-alcohol concentration (BAC) analysis was carried out at the Institute of forensic medicine in Novi Sad including 2023 two consecutive blood specimens using the Headspace Gas Chromatography method. Cases with no alcohol concentration values, as well as cases where blood samples were taken within 1 h after the criminal act, were not taken into consideration. Following this rule, 1198 cases were considered in this study and all samples were grouped in 29 ranges of BAC1 of delta(BAC) = 0.1 g/kg, starting from 0.1-0.19 g/kg to 2.9-2.99 g/kg of absolute alcohol. Gathered results and elimination curve differ from the zero-order model of elimination proposed by Widmark and point to an elimination process similar to a well-known Michaelis-Menten elimination kinetics model and its variants. Results reported in this study show dependence of alcohol elimination rate (beta-slope) and BAC value. The analysis of beta60-slope versus BAC shows that a correlation between beta60 (y) and BAC (x) has a logarithmic trend line. The value of alcohol elimination rate shows a slight increment with increase of BAC alcohol, with the mean value of beta60 = 0.221 +/- 0.075 g/kg. Differences in values of beta60 among consecutive intervals of delta(BAC) = 0.1 g/kg are not significant (p>0.05). When obtained samples were grouped into ranges of 0.5 g/kg each in these intervals beta60 had the following values by range: 0.1-0.49 g/kg = 0.139 g/kg +/- 0.035; 0.5-0.99 g/kg = 0.184 g/kg +/- 0.043; 1-1.49 g/kg = 0.213 g/kg +/- 0.052; 1.5-1.99 g/kg = 0.239 g/kg +/- 0.058; 2-2.49 g/kg = 0.265 g/kg +/- 0.073; 2.5-2.99 g/kg = 0.306 g/kg +/- 0.096. Differences in values of beta slope among consecutive intervals of delta(BAC) = 0.5 g/kg are significant (p<0.01). The elimination curve in the BAC interval 0.5-2.5 g/kg has a linear trend, while beta-slope (y)/BAC (x) correlation is given as beta60 = 0.15 g/kg + (0.05 g/kg x BAC). Retrograde calculation of the blood alcohol concentration in tempore criminis (BAC(tc)) based on the determined alcohol concentration in the blood specimen (BAC(t)) shows a statistically significant difference between BAC(tc) calculated using a standard zero-order model versus corrected methodology. The higher the BAC(t) and the longer the calculation time, the greater and statistically more significant (p<0.01) is the difference between the calculated values of BAC(tc).

Applications of population pharmacokinetics in current drug labelling

BACKGROUND AND OBJECTIVE

The application of population pharmacokinetics (PopPK) appears increasingly in drug labelling. The current study was to examine the use of PopPK in dose recommendation in drug-product labels.

METHOD

PopPK information was identified in the data sheets included in the physician desk reference (PDR). Electronic key word searches were conducted in the electronic library of PDR. The use of PopPK in the prescribing information, including the determination of dosing regimen, dosing in special populations and dose-adjustments was summarized and evaluated. The reliability and criteria for integrating the information derived from PopPK studies into the product labelling were discussed.

RESULTS AND DISCUSSION

Among more than 2500 items listed in the PDR, 88 listings were found to have PopPK information in the labelling. The information included general data (Gen) on pharmacokinetics (PK) and the effects of gender (sex), age, race, drug-drug interactions (DDI), smoking (Smk), alcohol consumption (Alc), disease state (Dis), renal impairment (Ren) and metabolic status (Met) on the PK parameters (Table). Whether there was an effect (+) or not (-) is also shown. Appendix 1 lists the products included in each category. Searches conducted at different times suggest an increase in both quantity and quality of PopPK data in drug development. PopPK is widely used in paediatric studies and the sample sizes in these studies are sometimes too small. The application of PopPK to protein drugs is increasing rapidly (Appendix 2). Several precautions should be exercised when PopPK is applied to protein drugs. When considering gender effects, different normalization methods for body weight have been used. The number of subjects included in the PopPK analysis should be given and the influence of the imbalance in any covariate should be investigated. PopPK-DDI results are particularly difficult to evaluate unless details about potentially influential factors such as dosing and sampling information for both drug and interacting drugs are given.

CONCLUSIONS

The use of PopPK to aid optimal dosing is increasing. Several noticeable problems raised usually avoid the acceptability of PopPK studies. More investigations are needed to inform the development of consensuses on these issues. There is an accelerating shift from PopPK to PopPK/PD. The limitations of such modelling should be recognized.

Sex and racial differences in pharmacological response: where is the evidence? Pharmacogenetics, pharmacokinetics, and pharmacodynamics

The Food and Drug Administration (FDA) reviewed 300 new drug applications between 1995 and 2000. Of the 163 that included a sex analysis, 11 drugs showed a >40% difference in pharmacokinetics between males and females, which was listed on the product label, yet no dosing recommendations were made based on sex. Female sex has been shown to be a risk factor for clinically relevant adverse drug reactions. Would simply dosing females based on their different pharmacokinetics decrease the incidence of adverse events? The answer is not known. Sex-dependent pharmacodynamic effects have been identified. The role of pharmacokinetics vs. pharmacodynamics is unclear, as is the impact of pharmacogenetics on both. This review highlights a few specific examples in each area in which sex differences in pharmacokinetics and pharmacodynamics are important and provides recommendations for additional needed research.

Effects of food on ethanol metabolism

The goals of the present study were (1) to obtain ethanol pharmacokinetic data from fed dogs, and (2) perform Monte Carlo simulation to determine the effect of food on pharmacokinetic model parameter values. To a cohort of five fed dogs, 1 g ethanol per km body weight was administered as a gavage of 20% w/v ethanol solution. Blood samples taken at 0, 10, 20, 30, 40, 60, 80, 100, 120, 180, 240, and 360 minutes after the dose were mixed with anticoagulant and stored on ice. Blood ethanol concentration was determined via headspace chromatograph. Monte Carlo simulation with an ethanol pharmacokinetic model was used to estimate model parameter values and parameter standard deviations by minimization of the chi-squared function. Results indicate that 50.6 +/- 21.0% of the ethanol dose was absorbed in the stomach, and an insignificant amount of ethanol was metabolized by gastric alcohol dehydrogenase postulated for the model. At 6 hours after the ethanol dose 59.4 +/- 21.0% of the ethanol dose was retained in the dogs' stomachs.

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.

The influence of sex on pharmacokinetics

Biologic differences exist between men and women that can result in differences in responses to drugs. Both pharmacokinetic and pharmacodynamic differences between the sexes exist, with more data on pharmacokinetic differences. On average, men are larger than women. Body size differences results in larger distribution volumes and faster total clearance of most medications in men compared to women. Greater body fat in women (until older ages) may increase distribution volumes for lipophilic drugs in women. Total drug absorption does not appear to be significantly affected by sex although absorption rates may be slightly slower in women. Bioavailability after oral drug dosing, for CYP3A substrates in particular, may be somewhat higher in women compared to men. Bioavailability after transdermal drug administration does not appear to be significantly affected by gender; nor does protein binding. Renal processes of glomerular filtration, tubular secretion, and tubular reabsorption appear to be faster in men compared to women whether considered on a mg/kg basis or total body weight basis. Algorithms to estimate glomerular filtration rate incorporate sex as a factor; some also include weight. For hepatic processes, drugs metabolized by Phase I metabolism (oxidation, reduction, and hydrolysis via cytochrome P450's 1A, 2D6, 2E1), Phase II conjugative metabolism (glucuronidation, conjugation, glucuronyltransferases, methyltransferases, dehydrogenases) and by combined oxidative and conjugation processes are usually cleared faster in men compared to women (mg/kg basis). Metabolism by CYP2C9, CYP2C19, and N-acetyltransferase, appear to be similar in men and women (mg/kg). Clearance of p-glycoprotein substrates appear to be similar in men and women. In contrast, total clearance of a number of CYP3A substrates appear to be mildly or moderately faster (mg/kg) in women compared to men. The clinical significance of reported differences warrants consideration. Clearance reported on a per kg basis directly addresses organ or enzyme clearance. The difference in size between men and women means translating these results to clinical dosage rates should include an adjustment for body size. Unfortunately, this is not standard. Reports of sex differences that persist after considering weight may warrant further dosage adjustments. In addition, investigations are often performed in healthy fasting individuals yet medications are prescribed to patients with confounding influences of disease, co-medications, diet, and social habits. The relative role of sex on pharmacokinetics as compared to genetics, age, disease, social habits and their potential interactions in the clinical setting is not yet fully known but should be routinely considered and further studied.

Moderate alcohol consumption reduces plasma C-reactive protein and fibrinogen levels; a randomized, diet-controlled intervention study

OBJECTIVE

To evaluate the effect of moderate alcohol consumption on the acute phase proteins C-reactive protein and fibrinogen.

DESIGN

Randomized, diet-controlled, cross-over study.

SETTING

The study was performed at TNO Nutrition and Food Research, Zeist, The Netherlands.

SUBJECTS

Ten middle-aged men and 10 postmenopausal women, all apparently healthy, non-smoking and moderate alcohol drinkers, were included. One women dropped out because of a treatment-unrelated cause. The remaining 19 subjects finished the experiment successfully.

INTERVENTIONS

Men consumed four glasses and women consumed three glasses of beer or no-alcohol beer (control) with evening dinner during two successive periods of 3 weeks. The total diet was supplied to the subjects and had essentially the same composition during these 6 weeks. Before each treatment there was a 1 week washout period to compensate for possible carry-over effects.

RESULTS

Plasma C-reactive protein and fibrinogen levels were decreased by 35% (P=0.02) and 12.4% (P< or =0.001), respectively, after 3 weeks' consumption of beer, as compared to no-alcohol beer consumption.

CONCLUSIONS

Moderate alcohol consumption significantly decreased plasma C-reactive protein and fibrinogen levels. An anti-inflammatory action of alcohol may help explain the link between moderate alcohol consumption and lower cardiovascular disease risk.

SPONSORSHIP

Dutch Foundation for Alcohol Research (SAR).

Ethanol intake during lactation. I. Effects On dams' metabolism and pups' body weight gain

Wistar lactating rats (8 pups per dam) had free access to either tap water (control group, C) or one of three concentrations of ethanol (E) in the drinking water: 5% (E5), 10% (E10), and 20% (E20). All animals received normal rat chow ad libitum and were killed on day 12 of lactation. Intake of both 10% and 20% ethanol solutions decreased food intake, dams' body weight, and pups' body weight gain as compared with findings in the C group. The relative weights (g/100g b.w.) of the mammary glands (MG) and of the parametrial white adipose tissue depot were decreased only in E20 as compared with findings in the C group. Protein and lipid content of these tissues were not altered in any of the ethanol groups. In comparison with the C group, the lipogenesis rate was increased in the MG (135. 6%) and liver (120.2%) in E5 and the MG (58.1%) and parametrial white adipose tissue depot (147.0%) in E20. No modifications in lipogenesis rate were noted in E10. The malic enzyme activity was decreased in the MG in E10 (25.3%) and E20 (26.4%) and in the liver in E20 (45.7%). In E5, however, it was increased in the liver (23. 9%). The activity of ATP-citrate lyase in the liver was decreased in E20 (56.7%), while it was increased by 37.5% in E5 and 34.2% in E10. Blood glucose concentration of dams was not affected by ethanol ingestion. However, plasma triacylglycerol concentration was higher in E10 (17.9%) and E20 (13.3%) than in the C group, and plasma protein was lower in E20 (15.7%) than in C. We concluded that alcohol intake during lactation increased the MG lipogenesis rate; although at the highest dose, this metabolic alteration was not enough to allow normal pups' growth. However, the low dose of ethanol (5%), despite having altered dams' metabolism, did not affect pups' body weight gain.

The Effects of Salty and Nonsalty Food on Peak Breath Alcohol Concentration and Divided Attention Task Performance in Women

There is recent evidence that gender-based patterns of alcohol consumption are becoming less dissimilar and that, per capita, women are consuming more alcohol than ever before. Therefore, a better understanding of the acute effects of moderate alcohol consumption in women is essential to establishing reliable health and safety educational information. To address one component of health and safety information, we sought to determine if peak breath alcohol concentrations (BAC) could be manipulated by varying the amount of sodium our women participants ingested in a test meal. We also measured the association between BAC and the participant's performance on a divided attention (DA) task. The 12 participants were trained to use a computer-generated DA task and subsequently participated in all of four experimental conditions. During each experimental session the participant consumed a placebo drink or a drink containing 0.6 g/kg ethanol and a 220-kcal portion of salted or unsalted pretzels. She then performed four 15-min trials of the DA task, after which the BAC was measured and recorded. Reaction times and mean tracking error were recorded for each DA trial. Experimental sessions took place at the same time on days 7, 8, 9, and 10 of the participant's menstrual cycle. The BAC was significantly higher in the ethanol plus sodium condition than in the ethanol with no sodium condition. Reaction times and tracking tasks were impaired in all ethanol conditions. Scores on the DA tasks obtained from the high-sodium group did not differ significantly from those of the low-sodium group. When health care personnel provide drug education for women clients, the possible BAC-elevating effects of consuming high-sodium foods while drinking alcoholic beverages should be discussed.

Sucrose administration to partially hepatectomized rats: a possible model to study ethanol-induced inhibition of liver regeneration

Although acute ethanol treatment drastically inhibits liver regeneration after partial hepatectomy, the exact mechanisms involved remain obscure. On the other hand, it is known that early carbohydrate administration promotes a more successful restoration of the liver mass. Therefore, carbohydrate administration could be an experimental approach for studying ethanol action on the regenerating liver. In rats subjected to two-thirds partial hepatectomy, ethanol was administered alone or in combination with a variety of carbohydrates (glucose, fructose, glucose plus fructose, sucrose and maltose). In liver samples, regeneration parameters and histological assessment were performed. Blood ethanol and metabolites reflecting liver function were assayed. Ethanol intake strongly decreased the incorporation of [3H]thymidine into liver DNA, the concentration of DNA/g of tissue, and thymidine kinase activity. In this group, severe alterations in cell structure (i.e. abundant fat droplets and abnormal mitochondria) were found. Carbohydrates readily improved the survival rate of ethanol-intoxicated hepatectomized rats. Sucrose was effective in reverting the ethanol-induced alterations in liver structure and the parameters of liver regeneration, and partially blocked the ethanol-induced alterations in serum levels of albumin, triacylglycerols and ammonia without modifying the blood levels and clearance of ethanol. Data suggest that the beneficial action of sucrose might be related to an adequate supply of energetic sources at early times of liver regeneration, rather than altering ethanol bioavailability. Thus, the present model could be an experimental approach for studying the metabolic alterations involved in the ethanol-induced inhibition of the liver regeneration.

Disposition and first-pass metabolism of ethanol in humans: is it gastric or hepatic and does it depend on gender?

OBJECTIVE

To assess the extent and site of the first-pass metabolism of ethanol and to examine whether first-pass metabolism and disposition of ethanol are dependent on gender.

METHODS

After a standardized lunch, healthy subjects (six women and six men) received on two separate occasions a 60-minute intravenous infusion of ethanol (0.3 gm/kg) and concomitantly an equimolar dose of d3-ethanol/kg either orally (over 20 minutes) or intraduodenally (infused over 30 minutes). Blood levels, urinary excretion of d0- and d3-ethanol, and sedative effects were monitored for 6 hours. Disposition and first-pass metabolism of ethanol were evaluated by applying an open two-compartment model with Michaelis-Menten elimination.

RESULTS

Comparison of the corresponding intravenous/oral versus intravenous/intraduodenal data of each individual revealed that total first-pass metabolism (gastric plus hepatic) was not pronounced in either males (9.1% +/- 4.0%; mean +/- SD) or females (8.4% +/- 3.1%) and that this first-pass metabolism was partly of gastric origin. Dose-corrected values for area under blood concentration-time curve were on average 28% higher (p < 0.0001) in the women than in the men. Mean total blood ethanol disappearance rate was higher (p < 0.001) in women (3.92 +/- 0.40 mmol/L . hr) than in men (3.19 +/- 0.48 mmol/L . hr). Renal clearance was gender-independent and negligible. A linear relationship (p < 0.001) could be found between the blood levels of ethanol and sedation index. Because the slope was steeper in women (1.04) than in men (0.42) a higher central nervous system sensitivity to the sedative effects of ethanol in women can be assumed.

CONCLUSIONS

Under realistic life conditions (social drinking of moderate doses of ethanol after a light lunch) only a minor, gender-independent first-pass metabolism is observed that is partly of gastric origin.

Gender differences in pharmacokinetics

There is growing awareness that the underrepresentation of women in clinical trials and in particular in phase I studies may lead to incorrect handling of drugs. Despite the fact that investigations are not informed in a systematic way, there are a number of examples showing pharmacokinetic differences between gender. From the data actually presented, it can be concluded that the activity of CYP 3A4 activity as measured by elimination in vivo is higher in women compared to men. CYP isoenzymes other than CYP 3A4 seem to be more active in men than in woman, as are conjugation reactions, such as glucuronidation. The influence of changing hormonal levels during the lifetime of a woman has been looked at in some drugs but deserves further systematic investigation. The use of oral contraceptives can interfere with the metabolism of many drugs whereas, in pregnancy, the elimination of antiepileptics is increased which, without dose adjustment, leads to an increased number of seizures. The impacts of hormonal replacement therapy (HRT) on the pharmacokinetics of concomitantly given drugs is an important issue, as HRT is increasingly used, but more research is needed in this field.

Inter-individual and intra-individual variability of ethanol concentration-time profiles: comparison of ethanol ingestion before or after an evening meal

1. The magnitude of the variability of ethanol absorption is an important factor for studies that seek to determine the significance of potential interactions between ethanol and drugs. The aim of this study was to determine the extent of inter- and intra-individual variability of ethanol concentration-time profiles in fasted and fed subjects. 2. Twenty-four healthy male subjects were randomized to receive ethanol 0.3 g kg-1 before an evening meal on two study days and ethanol 0.3 g kg-1 after an evening meal on two study days. Plasma ethanol concentrations were measured at intervals from 0-240 min. 3. There were significant differences in the mean area under the ethanol concentration-time curve (AUC), the mean peak ethanol concentration (Cmax), the mean ethanol elimination slope and the time to peak ethanol concentration between the fed and fasted subjects. There were no significant differences between the first and second study days for either fed or fasting subjects for all parameters. 4. There was no statistically significant difference in inter- or intra-subject variance between fed and fasted studies although the coefficients of variation (standard deviation expressed as a percentage of the mean) for the differences between the first and second study day were higher for fed studies. 5. The large inter- and intra-individual variability of alcohol absorption for both fasted and fed subjects must be considered in the design of alcohol-drug interaction studies.

Gender differences in human pharmacokinetics and pharmacodynamics

Gender differences in pharmacokinetics and pharmacodynamics have long been recognized in animals. In humans, however, little attention has been paid to this field despite at least theoretical reasons to believe that gender may be an important variable in the processes of absorption, distribution, metabolism, and excretion. Gastric acid secretion, gastrointestinal blood flow, proportions of muscular and adipose tissue, amount of drug binding proteins, gender-specific cytochrome P450 isozymes, physiologic and hormonal changes during the menstrual cycle, and renal blood flow are several factors that may contribute to sex-related differences in pharmacokinetics. Clinical investigations have documented greater absorption and subsequent incorporation of iron into erythrocytes, and higher bioavailability of ethanol in females. Women have been shown to have a slower metabolism of mephobarbital and propranolol but an increased biotransformation of methylprednisolone, all three of which are metabolized by enzymes of the cytochrome P450 system. Lastly, the renal excretion of amantadine was inhibited significantly by quinidine and quinine in men but not in women. While gender-specific pharmacodynamic data are meager, evidence also supports the existence of sex-related differences. Women appear to be more prone to develop torsades de points from drugs such as quinidine and procainamide than men. A dimorphism in insulin sensitivity has been demonstrated with males having an enhanced response compared to females. Pharmacokinetic and pharmacodynamic sex-related differences exist and are complex. Future research efforts should be designed to provide more gender-specific information on drug disposition and clinical effect.

The effect of food deprivation on alcohol consumption in bulimic and control women

The effect of food deprivation on alcohol self-administration was examined in five women with bulimia nervosa and five healthy controls in a semi-naturalistic experimental design. In this within-subjects study, each individual underwent two food-deprived and two non-deprived sessions. The deprivation condition consisted of no food or caloric beverages for 19 hours prior to the experimental procedure. On each of the 4 days, subjects watched a 2-hour segment of an epic movie and were permitted to drink ad libitum. No differences were observed in the number of grams of alcohol consumed under deprived and non-deprived conditions for either group. Breath alcohol levels were significantly higher under the non-deprived condition despite equivalent amounts of alcohol consumed and similar ratings of the subjective sense of tipsiness. Bulimic women consumed equivalent calories due to alcohol as control women but significantly fewer calories due to non-alcoholic beverages. These results do not support the hypothesis that food deprivation leads to increased self-administration of alcohol in women.

Retrograde extrapolation of blood alcohol data: an applied approach

Retrograde extrapolation is a mathematical process, based on sound scientific principles, that is used routinely in pharmacology, toxicology, and clinical medicine. This process may be applied to the situation of ethyl alcohol consumption with reliability when reasonable assumptions are made concerning absorption rates, elimination rates, and patterns of alcohol consumption, including drinking duration and volume consumed. By utilizing an established range of values for the elimination rate of alcohol of 0.015-0.020 g/dl/h, a relatively narrow range of extrapolated blood alcohol concentrations (BACs) can be determined in situations where the time frame in question is after peak alcohol absorption into the blood. A wider range of elimination rates of 0.01-0.03 g/dl/h may be applied and will satisfy the possibility of nonlinear kinetics within an individual; however, this wider range will have little practical effect on the predicted BACs. When the time point in question is prior to peak absorption, a wider range of predicted BAC values will result. The extent of this range will be influenced by the amount of information available concerning the temporal pattern of alcohol consumption. Reported drinking volumes are notoriously inaccurate and, in fact, are of little practical use. Given the parameters of body weight and time duration between initiation of drinking and determination of the BAC, the number of "drinks" consumed may be reliability calculated. Retrograde extrapolation is applicable in the forensic setting with scientific reliability when reasonable and justifiable assumptions are utilized.