Effect of concentration of ingested ethanol on blood alcohol levels

Integration of a physiologically-based pharmacokinetic model with a whole-body, organ-resolved genome-scale model for characterization of ethanol and acetaldehyde metabolism

Ethanol is one of the most widely used recreational substances in the world and due to its ubiquitous use, ethanol abuse has been the cause of over 3.3 million deaths each year. In addition to its effects, ethanol's primary metabolite, acetaldehyde, is a carcinogen that can cause symptoms of facial flushing, headaches, and nausea. How strongly ethanol or acetaldehyde affects an individual depends highly on the genetic polymorphisms of certain genes. In particular, the genetic polymorphisms of mitochondrial aldehyde dehydrogenase, ALDH2, play a large role in the metabolism of acetaldehyde. Thus, it is important to characterize how genetic variations can lead to different exposures and responses to ethanol and acetaldehyde. While the pharmacokinetics of ethanol metabolism through alcohol dehydrogenase have been thoroughly explored in previous studies, in this paper, we combined a base physiologically-based pharmacokinetic (PBPK) model with a whole-body genome-scale model (WBM) to gain further insight into the effect of other less explored processes and genetic variations on ethanol metabolism. This combined model was fit to clinical data and used to show the effect of alcohol concentrations, organ damage, ALDH2 enzyme polymorphisms, and ALDH2-inhibiting drug disulfiram on ethanol and acetaldehyde exposure. Through estimating the reaction rates of auxiliary processes with dynamic Flux Balance Analysis, The PBPK-WBM was able to navigate around a lack of kinetic constants traditionally associated with PK modelling and demonstrate the compensatory effects of the body in response to decreased liver enzyme expression. Additionally, the model demonstrated that acetaldehyde exposure increased with higher dosages of disulfiram and decreased ALDH2 efficiency, and that moderate consumption rates of ethanol could lead to unexpected accumulations in acetaldehyde. This modelling framework combines the comprehensive steady-state analyses from genome-scale models with the dynamics of traditional PK models to create a highly personalized form of PBPK modelling that can push the boundaries of precision medicine.

Wearable Electrochemical Sensors for the Monitoring and Screening of Drugs

Wearable electrochemical sensors capable of noninvasive monitoring of chemical markers represent a rapidly emerging digital-health technology. Recent advances toward wearable continuous glucose monitoring (CGM) systems have ignited tremendous interest in expanding such sensor technology to other important fields. This article reviews for the first time wearable electrochemical sensors for monitoring therapeutic drugs and drugs of abuse. This rapidly emerging class of drug-sensing wearable devices addresses the growing demand for personalized medicine, toward improved therapeutic outcomes while minimizing the side effects of drugs and the related medical expenses. Continuous, noninvasive monitoring of therapeutic drugs within bodily fluids empowers clinicians and patients to correlate the pharmacokinetic properties with optimal outcomes by realizing patient-specific dose regulation and tracking dynamic changes in pharmacokinetics behavior while assuring the medication adherence of patients. Furthermore, wearable electrochemical drug monitoring devices can also serve as powerful screening tools in the hands of law enforcement agents to combat drug trafficking and support on-site forensic investigations. The review covers various wearable form factors developed for noninvasive monitoring of therapeutic drugs in different body fluids and toward on-site screening of drugs of abuse. The future prospects of such wearable drug monitoring devices are presented with the ultimate goals of introducing accurate real-time drug monitoring protocols and autonomous closed-loop platforms toward precise dose regulation and optimal therapeutic outcomes. Finally, current unmet challenges and existing gaps are discussed for motivating future technological innovations regarding personalized therapy. The current pace of developments and the tremendous market opportunities for such wearable drug monitoring platforms are expected to drive intense future research and commercialization efforts.

Modeling Relapse to Pavlovian Alcohol-Seeking in Rats Using Reinstatement and Spontaneous Recovery Paradigms

BACKGROUND

Animal models are critical for studying causal explanations of relapse. Using a Pavlovian conditioning procedure with alcohol, we examined relapse after extinction triggered by either re-exposure to alcohol (reinstatement) or a delay between extinction and test (spontaneous recovery).

METHODS

Male, Long-Evans rats were acclimated to 15% alcohol in the home-cage using an intermittent-access 2-bottle choice procedure. Next, they received Pavlovian conditioning sessions in which an auditory-conditioned stimulus (CS; 20 second white noise; 8 trials/session; variable time 240 seconds) was paired with 15% alcohol (0.3 ml/CS; 2.4 ml/session) that was delivered into a fluid port for oral ingestion. In subsequent extinction and test sessions, CS presentations occurred as before, but without alcohol.

RESULTS

In experiment 1, exposure to either alcohol or water in the fluid port following extinction reinstated CS-elicited port entries at test 24 hours later. In a follow-up study using the same procedure (experiment 2), reinstatement was more robustly stimulated by alcohol, compared to a familiar lemon-flavored liquid. In experiment 3, systemic alcohol injections (0, 0.5, or 1.0 g/kg, intraperitoneal) administered either 24 hours or 15 minutes before test did not reinstate CS-elicited alcohol-seeking. Importantly, enzymatic assays in experiment 4 revealed detectable levels of alcohol in the blood following oral alcohol intake or intraperitoneal injection, suggesting that a pharmacological effect was likely with either route of administration. Last, in experiment 5, a 23-day delay between extinction and test resulted in a robust spontaneous recovery of CS-elicited alcohol-seeking.

CONCLUSIONS

The reinstatement and spontaneous recovery effects revealed herein provide evidence of viable new behavioral paradigms for testing interventions against relapse.

Animal models of binge drinking, current challenges to improve face validity

Binge drinking (BD), i.e., consuming a large amount of alcohol in a short period of time, is an increasing public health issue. Though no clear definition has been adopted worldwide the speed of drinking seems to be a keystone of this behavior. Developing relevant animal models of BD is a priority for gaining a better characterization of the neurobiological and psychobiological mechanisms underlying this dangerous and harmful behavior. Until recently, preclinical research on BD has been conducted mostly using forced administration of alcohol, but more recent studies used scheduled access to alcohol, to model more voluntary excessive intakes, and to achieve signs of intoxications that mimic the human behavior. The main challenges for future research are discussed regarding the need of good face validity, construct validity and predictive validity of animal models of BD.

Morphological and biochemical effects of weekend alcohol consumption in rats: Role of concentration and gender

AIM

To examine the association between weekend alcohol consumption and the biochemical and histological alterations at two different concentrations of alcohol in both genders in rats.

METHODS

Wistar rats weighing 170-200 g were divided into groups as follows: (1) Control groups; and (2) weekend alcohol-consumption group: 2 d/weekly per 12 wk, at two different concentrations: (1) Group of males or females with a consumption of a solution of alcohol at 40%; and (2) group of males or females with a consumption of a solution of alcohol at 5%. At the end of the experiment, serum and liver samples were obtained. The following enzymes and metabolites were determined in serum: Alanine Aminotransferase (ALT), Aspartate Aminotransferase (AST), Lactate Dehydrogenase, and Gamma-Glutamyltransferase, and glucose, triglycerides, cholesterol, bilirubin, and albumin. Liver samples from each group were employed to analyze morphological abnormalities by light microscopy.

RESULTS

In all of the weekend alcohol-consumption groups, AST activity presented a significant, 10-fold rise. Regarding ALT activity, the groups with weekend alcohol consumption presented a significant increase that was six times greater. Bilirubin levels increased significantly in both groups of females. We observed a significant increase in the parameters of fatty change and inflammation due to weekend alcohol consumption. Only the group of females that consumed alcohol at 40% presented slight hepatocellular disorganization

CONCLUSION

The results obtained herein provide solid evidence that weekend alcohol consumption gives rise to liver damage, demonstrated by biochemical and histological alterations, first manifested acutely, and prolonged weekend alcohol consumption can cause greater, irreversible damage.

Alcohol Drinking and Blood Alcohol Concentration Revisited

BACKGROUND

It is widely assumed that the amount of alcohol in the blood reflects the amount of alcohol consumed. However, several factors in addition to amount of alcohol consumed can influence blood alcohol concentration (BAC). This study examines the effect of alcohol dose, concentration, and volume on BAC in rats with a high-alcohol-drinking (HAD) phenotype.

METHODS

Study 1 examined the relationship between the amount of alcohol consumed and BAC. Alcohol-naïve, male, HAD rats (N = 7) were given access to alcohol for 2 h/d for 9 consecutive days with food and water ad libitum. Alcohol intake and BAC were measured at 30, 60, and 90 minutes after onset of access. Study 2 examined the effects of altering alcohol dose, concentration, and volume on BAC (as measured by area under the curve). Alcohol-naïve, male, HAD rats (N = 39) were infused, via an intragastric cannulus, with 1.16, 2.44, or 3.38 g alcohol/kg body weight (BW), produced by varying alcohol volume while holding concentration constant or by holding volume constant while varying concentration. Other rats were infused with 10, 15, or 20% v/v alcohol solutions while holding dose constant.

RESULTS

BAC was more strongly correlated with the ratio of alcohol intake (g/kg BW) to total fluid intake (mls) (R = 0.85 to 0.97, p < 0.05 to p < 0.001) than it was with the amount of alcohol consumed (g/kg BW) (R = 0.70 to 0.81, p < 0.05). No effect of alcohol dose was seen during the first hour following the onset of an alcohol infusion regardless of whether dose was achieved by altering alcohol volume or concentration. After 1 hour, higher alcohol doses were predictive of greater BACs.

CONCLUSIONS

The fact that a 3-fold difference in alcohol dose did not result in significant differences in BACs during the first 30 minutes after ingestion of alcohol has potentially important implications for interpretation of studies that measure alcohol-sensitive end points during this time.

Effects of acute alcohol intoxication on executive functions controlling self-regulated behavior

Alcohol consumption may lead to deficits in the executive functions that govern self-regulation. These deficits could lead to risk-taking behaviors; therefore, it is important to determine the magnitude of these deficits on executive functioning. The purpose of this experiment was to investigate the acute effects of alcohol on three of the executive functions that are hypothesized to affect self-regulation, which are inhibition, set shifting, and working memory, using a mixed-methods study design. The participants were 75 moderate or heavy drinkers between the ages of 21 and 35 who were randomized into one of three beverage conditions (control, placebo, or 0.65-g alcohol dose/kg body weight). Performance on working memory, set shifting, and inhibition were measured pre- and post-beverage consumption. The results showed only a significant interaction in the working memory data, as there was an increase in performance post-beverage relative to pre-beverage for the control participants as compared to the alcohol and placebo participants. It was concluded that the dose of alcohol (BAC = 0.063%) given to moderate to heavy drinkers was not sufficient to cause significant impairment in the executive functions tested. The results were further discussed and methodological concerns were considered, such as the low BAC achieved, practice effects, and insensitivity of tasks.

Absorption and peak blood alcohol concentration after drinking beer, wine, or spirits

Background

Both the amount and the rate of absorption of ethanol (EtOH) from alcoholic beverages are key determinants of the peak blood alcohol concentration (BAC) and exposure of organs other than gut and liver. Previous studies suggest EtOH is absorbed more rapidly in the fasting than in the postprandial state. The concentration of EtOH and the type of beverage may determine gastric emptying/absorption of EtOH.

Methods

The pharmacokinetics of EtOH were measured in 15 healthy men after consumption of 0.5 g of EtOH/kg body weight. During this 3‐session crossover study, subjects consumed in separate sessions, beer (5.1% v/v), white wine (12.5% v/v), or vodka/tonic (20% v/v) over 20 minutes following an overnight fast. BAC was measured by gas chromatography at multiple points after consumption.

Results

Peak BAC (C_max) was significantly higher (p < 0.001) after vodka/tonic (77.4 ± 17.0 mg/dl) than after wine (61.7 ± 10.8 mg/dl) or beer (50.3 ± 9.8 mg/dl) and was significantly higher (p < 0.001) after wine than beer. The time to C_max occurred significantly earlier (p < 0.01) after vodka/tonic (36 ± 10 minutes) compared to wine (54 ± 14 minutes) or beer (62 ± 23 minutes). Six subjects exceeded a C_max of 80 mg/dl after vodka/tonic, but none exceeded this limit after beer or wine. The area under the concentration–time curve (AUC) was significantly greater after drinking vodka/tonic (p < 0.001) than after wine or beer. Comparison of AUCs indicated the relative bioavailability of EtOH was lower after drinking beer.

Conclusions

Findings indicate that BAC is higher after drinking vodka/tonic than beer or wine after fasting. A binge pattern is significantly more likely to result in BAC above 80 mg/dl after drinking vodka/tonic than beer or wine. Men drinking on an empty stomach should know BAC will vary depending on beverage type and the rate and amount of EtOH.

Biotransformation of ethanol to ethyl glucuronide in a rat model after a single high oral dosage

Ethyl glucuronide (EtG) is a minor ethanol metabolite that confirms the absorption and metabolism of ethanol after oral or dermal exposure. Human data suggest that maximum blood EtG (BEtG) concentrations are reached between 3.5 and 5.5h after ethanol administration. This study was undertaken to determine if the Sprague-Dawley (SD) rat biotransforms ethanol to EtG after a single high oral dose of ethanol. SD rats (male, n=6) were gavaged with a single ethanol dose (4 g/kg), and urine was collected for 3 h in metabolic cages, followed by euthanization and collection of heart blood. Blood and urine were analyzed for ethanol and EtG by gas chromatography and enzyme immunoassay. Blood and urine ethanol concentrations were 195±23 and 218±19 mg/dL, whereas BEtG and urine EtG (UEtG) concentrations were 1,363±98 ng equivalents/mL and 210±0.29 mg equivalents/dL (X ± standard error of the mean [S.E.M.]). Sixty-six male SD rats were gavaged ethanol (4 g/kg) and placed in metabolic cages to determine the extent and duration of ethanol to EtG biotransformation and urinary excretion. Blood and urine were collected up to 24 h after administration for ethanol and EtG analysis. Maximum blood ethanol, urine ethanol, and UEtG were reached within 4 h, whereas maximum BEtG was reached 6 h after administration. Maximum concentrations were blood ethanol, 213±20 mg/dL; urine ethanol, 308±34 mg/dL; BEtG, 2,683±145 ng equivalents/mL; UEtG, 1.2±0.06 mg equivalents/mL (X±S.E.M.). Areas under the concentration-time curve were blood ethanol, 1,578 h*mg/dL; urine ethanol, 3,096 h*mg/dL; BEtG, 18,284 h*ng equivalents/mL; and UEtG, 850 h*mg equivalents/dL. Blood ethanol and BEtG levels were reduced to below limits of detection (LODs) within 12 and 18 h after ethanol administration. Urine ethanols were below LOD at 18 h, but UEtG was still detectable at 24h after administration. Our data prove that the SD rat biotransforms ethanol to EtG and excretes both in the urine and suggest that it is similar to that of the human.

Selection of film clips and development of a video for the investigation of sexual decision making among men who have sex with men

Experimental research on sexual decision making is limited, despite the public health importance of such work. We describe formative work conducted in advance of an experimental study designed to evaluate the effects of alcohol intoxication and sexual arousal on risky sexual decision making among men who have sex with men. In Study 1, we describe the procedures for selecting and validating erotic film clips (to be used for the experimental manipulation of arousal). In Study 2, we describe the tailoring of two interactive role-play videos to be used to measure risk perception and communication skills in an analog risky sex situation. Together, these studies illustrate a method for creating experimental stimuli to investigate sexual decision making in a laboratory setting. Research using this approach will support experimental research that affords a stronger basis for drawing causal inferences regarding sexual decision making.

Kinetics of ethanol decay in mouth- and nose-exhaled breath measured on-line by selected ion flow tube mass spectrometry following varying doses of alcohol

A study has been carried out of the decay of ethanol in mouth-exhaled and nose-exhaled breath of two healthy volunteers following the ingestion of various doses of alcohol at different dilutions in water. Concurrent analyses of sequential single breath exhalations from the two volunteers were carried out using selected ion flow tube mass spectrometry, SIFT-MS, on-line and in real time continuously over some 200 min following each alcohol dose by simply switching sampling between the two volunteers. Thus, the time interval between breath exhalations was only a few minutes, and this results in well-defined decay curves. Inspection of the mouth-exhaled and nose-exhaled breath data shows that mouth contamination of ethanol diminished to insignificant levels after a few minutes. The detailed results of the analyses of nose-exhaled breath show that the peak levels and the decay rates of breath ethanol are dependent on the ethanol dose and the volume of ethanol/water mixture ingested. From these data, both the efficiency of the first-pass metabolism of ethanol and the indications of gastric emptying rates at the various doses and ingested volumes have been obtained for the two volunteers. Additionally and simultaneously, acetaldehyde, acetic acid and acetone were measured in each single breath exhalation. Acetaldehyde, the primary product of ethanol metabolism, is seen to track the breath ethanol. Acetic acid, a possible secondary product of this metabolism, was detected in the exhaled breath, but was shown to largely originate in the oral cavity. Breath acetone was seen to increase over the long period of measurement due to the depletion of nutrients.

The effect of ethanol on the release of opioids from oral prolonged-release preparations

Recent experience has prompted the US FDA to consider whether ethanol ingestion may modify the release characteristics of prolonged-release formulations, where dose dumping may be an issue for patient safety. The influence of ethanol on the in vitro release of opioid drugs from some prolonged-release formulations utilizing different release technologies was examined. Results indicated that the prolonged-release mechanisms remained intact under the testing conditions, although one product showed initial sensitivity to ethanol in its release characteristics. Nevertheless, in this case, extrapolation of the findings to likely outcome in vivo indicated no risk of dose-dumping. It is proposed that prolonged-release medicinal products should be tested during development to ensure robustness to the effects of ethanol on drug release.

Alcohol concentration and carbonation of drinks: The effect on blood alcohol levels

Alcohol absorption and elimination vary considerably amongst individuals, and are subject to influences from a variety of factors. The effects of alcohol concentration and beverage mixer type on the rate of alcohol absorption, in a controlled environment was studied. 21 subjects (12 male, 9 female) consumed a solution containing alcohol, on three separate occasions. The three solutions were, A: Neat vodka (37.5 vol%), B: Vodka mixed with still water (18.75 vol%), C: Vodka mixed with carbonated water (18.75 vol%). The volume of alcohol each subject consumed was determined by Widmark's equation. The alcohol was drunk in a 5 min period following an overnight fast and breath alcohol concentrations were measured over a 4h period using a breathalyser. 20/21 subjects absorbed the dilute alcohol at a faster rate than the concentrated alcohol. The difference between the absorption rates was found to be significant (p<0.001). The use of a carbonated mixer had varying effects on the alcohol absorption rate. 14/21 subjects absorbed the alcohol with the carbonated mixer at a faster rate, with 7 subjects showing either no change or a decrease in rate. The mean absorption rate for solution C was 4.39+/-0.45 (mg/100ml/min), and the difference between this absorption rate and that with the still mixer (1.08+0.36) was significant (p=0.006).

Effect of Chronic Ethanol Consumption on the Response of Parathyroid Hormone to Hypocalcemia in the Pregnant Rat

BACKGROUND

Chronic alcohol (ethanol) consumption during pregnancy results in maternal/fetal hypocalcemia, which may underlie some of ethanol's adverse effects on maternal and fetal bone, and fetal/neonatal health. Ethanol appears to alter the relationship between parathyroid hormone (PTH) and blood calcium (Ca) level, and PTH does not increase in response to ethanol-induced hypocalcemia. However, it is not known whether ethanol actually prevents PTH from responding, or whether the ability to regulate blood Ca is intact, but ethanol lowers the level of Ca maintained. The objective of this study was to determine whether chronic ethanol consumption impairs the ability of the pregnant female to increase PTH in response to acute hypocalcemia.

METHODS

Rats were fed isocaloric diets with ethanol (36% ethanol-derived calories, E group) or without ethanol [pair-fed (PF) and control (C) groups], before and throughout 21 days of gestation. On day 21 gestation, rats received an intraperitoneal injection of ethylene glycol-bis (beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) (300 or 500 mumol/kg body weight) or saline (saline group), or no injection (baseline group). Blood was collected from the baseline group, and at 30 or 60 minutes postinjection (saline and EGTA groups), and analyzed for ionized Ca (iCa), pH, and PTH.

RESULTS

Consistent with previous studies, ethanol consumption decreased blood iCa levels at baseline, but PTH levels did not differ among groups. Administration of EGTA significantly decreased blood iCa levels by 30 minutes, but ethanol did not prevent PTH from increasing in response to the hypocalcemia. In all diet groups, PTH levels were significantly increased by 30 minutes. Ethanol did, however, appear to decrease the maximum PTH level achievable in blood.

CONCLUSIONS

These data suggest that chronic ethanol consumption does not impair the ability of the pregnant rat to raise serum PTH levels in response to acute hypocalcemia, but ethanol's effect on maximal PTH secretion could impair the ability of the pregnant female to sustain high PTH levels in response to chronic hypocalcemia.

The effects of pregnancy on ethanol clearance

We have studied the effects of pregnancy on ethanol clearance rates and on blood and urine ethanol concentrations (BECs and UECs) in adult Sprague-Dawley rats infused with ethanol intragastrically. Pregnant rats had greater ethanol clearance following an intragastric or intravenous ethanol bolus (3 or 0.75 g/kg, respectively) relative to non-pregnant rats (p<0.05). Pregnant rats infused with ethanol-containing diets for several days had lower (p<0.05) UECs than non-pregnant rats when given the same dose of ethanol. Non-pregnant rats infused ethanol-containing diets at two levels of calories (the higher caloric intake required by pregnant rats [220 kca/kg75/d] or the normal calories required for non-pregnant rats [187 kcal/kg75/d]) had statistically equal UECs, suggesting that increased caloric intake was not responsible for the effect of pregnancy. While the activity of hepatic alcohol dehydrogenase (ADH) did not differ with pregnancy, gastric ADH activity was increased (p<0.001). Furthermore, total hepatic aldehyde dehydrogenase (ALDH) and hepatic mitrochrondrial protein were increased (p<0.05) and hepatic CYP2E1 activity was suppressed (p<0.05). The results suggest that pregnancy increases ethanol elimination in pregnant rats by: 1) induction of gastric ADH; 2) elevated hepatic ALDH activity; and 3) increased mitochondrial respiration. The greater ethanol clearance results in lower tissue ethanol concentrations achieved during pregnancy for a given dose, and this may have clinical significance as a mechanism to protect the growing fetus from ethanol toxicity.

Neuroimaging of Rodent and Primate Models of Alcoholism: Initial Reports From the Integrative Neuroscience Initiative on Alcoholism

Neuroimaging of animal models of alcoholism offers a unique path for translational research to the human condition. Animal models permit manipulation of variables that are uncontrollable in clinical, human investigation. This symposium, which took place at the annual meeting of the Research Society on Alcoholism in Vancouver, British Columbia, Canada, on June 29th, 2004, presented initial findings based on neuroimaging studies from the two centers of the Integrative Neuroscience Initiative on Alcoholism funded by the National Institute on Alcohol Abuse and Alcoholism. Effects of alcohol exposure were assessed with in vitro glucose metabolic imaging of rat brain, in vitro receptor imaging of monkey brain, in vivo magnetic resonance imaging of monkey brain, and in vivo magnetic resonance spectroscopic quantification of alcohol metabolism kinetics in rat brain.

Metabolism of alcohol

Most tissues of the body contain enzymes capable of ethanol oxidation or nonoxidative metabolism, but significant activity occurs only in the liver and, to a lesser extent, in the stomach. Hence, medical consequences are predominant in these organs. In the liver, ethanol oxidation generates an excess of reducing equivalents, primarily as NADH, causing hepatotoxicity. An additional system, containing cytochromes P-450 inducible by chronic alcohol feeding, was demonstrated in liver microsomes and found to be a major cause of hepatotoxicity.

Population Pharmacokinetics of Ethanol in Drinking Drivers Using Breath Measures

This study was undertaken to evaluate the population pharmacokinetic behavior of ethanol from breath ethanol measures and to see if these results could be used to establish the drinking history of our drinking drivers. The population consisted of 55 self-identified light to heavy drinkers. All had been arrested at least once for driving under the influence of alcohol. Sixteen were women, and 39 were men. Breath was analyzed for ethanol using a 3-wavelength infrared spectrophotometer. An iterative 2-stage Bayesian (IT2B) parametric modeling program was used first to obtain gamma, a measure of the relative magnitude of the intraindividual variability. The nonparametric adaptive grid (NPAG) maximum likelihood program, using gamma, was then used to obtain the full nonparametric joint parameter density. A 2-compartment Michaelis-Menten model was evaluated. The 2-compartment model gave a gamma of 1.75. Thus, the standard deviation (SD) of the nonassay sources of intraindividual variability was 1.75 times the SD of the assay itself for the 2-compartment model. The NPAG program gave the following means, medians, modes, and standard deviations for the 2-compartment model: ka (h(-1)) = 6.43, 5.46, 2.93, 4.58; Vmax (g/h) = 12.09, 11.90, 13.03, 3.73; Km (g/L) = 0.1273, 0.1367, 0.1991, 0.0528; Vc (L) = 31.32, 29.30, 24.88, 10.52; kcp (h(-1)) = 4.38, 1.30, 1.12, 6.16; and kpc (h(-1)) = 9.11, 2.47, 0.89, 8.98. These drinking drivers had a rate of metabolism of ethanol that was between that of moderate drinkers and confirmed alcoholics. Properly collected breath ethanol measures can be useful in a therapeutic drug-monitoring situation to obtain quick, accurate, and reliable measures of a patient's ethanol concentrations.

Acute alcohol administration improves skilled reaching success in intact but not 6-OHDA dopamine depleted rats: a subsystems analysis of the motoric and anxiolytic effects of alcohol

Low doses of alcohol impair movement and reduce anxiety. Most assessments of movement under ethyl alcohol (alcohol) in the rat have been tests of whole body movements, however. There has been no examination of the effects of alcohol on skilled limb movements, such as reaching for food with a forelimb. This was the purpose of the present study. Rats were trained to reach through a slot of a box with a forelimb in order to obtain a food pellet located on an external shelf. Once asymptotic performance was achieved, rats were given alcohol (20 ml of 8, 12 or 20% (v/v) solution) in separate tests to establish a relationship between alcohol ingestion and skilled reaching performance. Acute treatment with all doses of alcohol impaired postural support, but doses of 8 and 12% alcohol improved skilled reaching success. Qualitative analysis of the movements used for reaching at doses of 8 and 12% indicated that some limb components of the reaching movement were also impaired, perhaps secondarily due to impaired posture. In contrast, the reaching success of rats with unilateral dopamine depletion, induced with the neurotoxin 6-hydroxydopamine (6-OHDA) in the nigrostriatal bundle, was impaired by the same dose of alcohol that improved reaching success in control rats. The finding of improved success in reaching associated with reduced postural support in normal rats suggests a differential action of alcohol on movement subsystems underlying posture relative to skilled movement that depends upon an intact dopaminergic system. The results are also discussed with respect to the relationship of subsystems of movement and anxiety.

Alcohol metabolism: role in toxicity and carcinogenesis

This article contains the proceedings of a symposium at the 2002 RSA Meeting in San Francisco, organized and co-chaired by Thomas M. Badger, Paul Shih-Jiun Yin, and Helmut Seitz. The presentations were (1) First-pass metabolism of ethanol: Basic and clinical aspects, by Charles Lieber; (2) Intracellular CYP2E1 transport, oxidative stress, cytokine release, and ALD, by Magnus Ingelman-Sundberg; (3) Pulsatile ethanol metabolism in intragastric infusion models: Potential role in toxic outcomes, by Thomas M. Badger and Martin J.J. Ronis; (4) Free radicals, adducts, and autoantibodies resulting from ethanol metabolism: Role in ethanol-associated toxicity, by Emanuele Albano; and (5) Gastrointestinal metabolism of ethanol and its possible role in carcinogenesis, by Helmut Seitz.

Gender differences in alcohol metabolism. Physiological responses to ethanol

A gender difference in alcohol pharmacokinetics has been suggested to explain why women are more vulnerable to ethanol's toxic effects. The results of animal experiments suggest that females exhibit higher alcohol metabolic rates than males as a result of hormonal differences. Experimental results examining gender differences in human alcohol metabolism have been inconsistent; the diversity of experimental protocols and variety of pharmacokinetic parameters reported have made comparisons of these studies very difficult. Variability in alcohol metabolic rate between individuals of the same sex is often significant, preventing an assessment of gender differences in some studies. This chapter attempts to summarize the findings of studies from the last decade that examined the role of gender and sex hormone differences on ethanol metabolism in men and women. The role of body composition, genetic factors, gastric and hepatic alcohol dehydrogenase, and gastric absorption in creating gender differences in alcohol metabolism is discussed. Suggestions are offered that may result in better cross-study comparisons and more consistent experimental results.

Different alcohol drinking and blood pressure relationships in France and Northern Ireland: The PRIME Study

To assess the effect of alcoholic beverages consumed on blood pressure levels by day of the week, baseline data from the Prospective Epidemiological Study of Myocardial Infarction (PRIME), including 6523 male subjects who drank at least once a week (5156 in France and 1367 in Northern Ireland), were analyzed. In France, alcohol consumption was rather homogeneous throughout the week, with a slight increase during weekends, whereas in Northern Ireland, Fridays and Saturdays accounted for 66% of total alcohol consumption. After adjustment for age, body mass index, heart rate, tobacco smoking, educational level, marital status, and professional activity, blood pressure levels were higher in Northern Irish drinkers on Monday and decreased until Thursday, whereas blood pressure levels were constant throughout the week for French drinkers (day x country interactions, P<0.05). Conversely, no between-day differences were found regarding teetotalers in both countries. In drinkers, between-day differences and day x country interactions were suppressed after adjustment for the average alcohol consumption of the third day before measurement. We conclude that the binge-drinking pattern observed among Northern Irish drinkers leads to physiologically disadvantageous consequences regarding blood pressure levels, whereas no such fluctuations in blood pressure levels are found for regular consumption.

Gender differences in pharmacokinetics of alcohol

BACKGROUND

The enhanced vulnerability of women to develop alcohol-related diseases may be due to their higher blood alcohol levels after drinking, but the mechanism for this effect is debated.

METHODS

Sixty-five healthy volunteers of both genders drank 0.3 g of ethanol/kg of body weight (as 5%, 10%, or 40% solutions) postprandially. Blood alcohol concentrations were monitored by breath analysis and compared with those after intravenous infusion of the same dose. First-pass metabolism was quantified (using Michaelis-Menten kinetics) as the route-dependent difference in the amount of ethanol reaching the systemic blood. Gastric emptying was assessed by nuclear scanning after intake of 300 microCurie of technetium-labeled diethylene triamine pentacetic acid in 10% ethanol. The activities of alcohol dehydrogenase isozymes were assessed in 58 gastric biopsies, using preferred substrates for gamma-ADH (acetaldehyde) and for final sigma-ADH (m-nitrobenzaldehyde) and a specific reaction of chi-ADH (glutathione-dependent formaldehyde dehydrogenase).

RESULTS

Women had less first-pass metabolism than men when given 10% or 40%, but not 5%, alcohol. This was associated with lower gastric chi-ADH activity; its low affinity for ethanol could explain the greater gender difference in first-pass metabolism with high rather than with low concentrations of imbibed alcohol. Alcohol gastric emptying was 42% slower and hepatic oxidation was 10% higher in women. A 7.3% smaller volume of alcohol distribution contributed to the higher ethanol levels in women, but it did not account for the route-dependent effects.

CONCLUSIONS

The gender difference in alcohol levels is due mainly to a smaller gastric metabolism in females (because of a significantly lesser activity of chi-ADH), rather than to differences in gastric emptying or in hepatic oxidation of ethanol. The concentration-dependency of these effects may explain earlier discrepancies. The combined pharmacokinetic differences may increase the vulnerability of women to the effects of ethanol.

Alcohol levels are increased in social drinkers receiving ranitidine

OBJECTIVE

Ranitidine increases blood alcohol concentrations by decreasing the first pass metabolism of ethanol. The effect of ranitidine on alcohol levels has been found to be variable when using large doses of alcohol or conditions in which its first pass metabolism is known to be minimal. Despite a consensus that the drug increases alcohol levels after small doses of ethanol, this effect has been considered inconsequential, because of the low alcohol levels. However, social drinking comprises repetitive consumption of small doses of alcohol and the ranitidine effect could thereby be potentiated.

METHODS

To study this factor, alcohol levels were determined by breath analysis in nine men (social drinkers), after four drinks of 0.15 g/kg ethanol given postprandially every 45 min, before and after ranitidine (150 mg b.i.d. for 7 days).

RESULTS

Their blood alcohol increased with repeated doses, reaching peak values of 24+/-3 mg/dl before ranitidine and 33+/-2 after ranitidine (p = 0.04). In seven of the nine subjects blood alcohol exceeded 25 mg/dl, a level at which impairment of judgment and of finely tuned skills occurs and which exceeds legal limits of driving in some European countries. Moreover, the high levels persisted for a longer time with than without the drug. These effects were associated with a 62% decrease in first pass metabolism.

CONCLUSION

Under conditions mimicking social drinking, ranitidine increases blood alcohol to levels known to impair psychomotor skills needed for driving.

Is there an interaction between H2-antagonists and alcohol?

H2-antagonists are commonly prescribed drugs and alcohol use is widespread in the community. Any possible interaction may be important because of the frequent co-administration of both drugs and the potential for unexpected impairment of pyschomotor function, in particular, driving skills. Hepatic ADH is the major site of alcohol metabolism. ADH is also found in the stomach, but it is uncertain whether gastric ADH is able to metabolise a significant amount of alcohol in vivo. Significant first-pass metabolism can be demonstrated at lower doses of alcohol, and if alcohol is given after meals. Varying degrees of extraction of alcohol from the portal circulation probably explains the data regarding first pass metabolism rather than gastric metabolism by gastric ADH. H2-receptor antagonists inhibit gastric ADH activity to a variable extent. If gastric metabolism of alcohol is negligible then this inhibition has no relevance. Given the uncertainty regarding a mechanism of interaction, only carefully conducted studies in controlled environments will answer the question. The large inter-subject variability of alcohol absorption means that any study which seeks to determine the effect of an H2-receptor antagonist on ethanol metabolism must have sufficient numbers. A cross-over design, with each subject acting as his own control, is preferable to avoid ascribing an effect to treatment rather than to chance. The alcohol dosing studies are reviewed and the results summarised according to dose of alcohol given. At a dose of 0.15 g/kg of alcohol, four commonly used H2-antagonists may cause a small increase in blood alcohol concentrations in certain conditions. This absolute increase is very small. The magnitude of effect is far less than the effect of taking a meal before alcohol. At doses of 0.3 g/kg and above the majority of evidence favours no interaction between H2-antagonists and alcohol. There is no interaction at doses that would be expected to impair psychomotor skills (above 25 mg/dl). There remains a question regarding the cumulative effect of repeated small doses of alcohol and further studies are required. The relationship between ethanol absorption and gastric emptying raises the possibility that the effects of H2-receptor antagonists observed at very low doses of alcohol may be due to the acceleration of gastric emptying by these drugs. This is an attractive hypothesis that explains many aspects of the debate, but studies of the effect of H2-antagonists on gastric emptying have been conflicting.

Effects of ethanol ingestion on epididymal glycosidases and fertility in the rat

Epididymal glycosidases play a role in sperm maturation by modifying sperm surface glycoproteins. To study the effects of ethanol on epididymal sperm maturation, ethanol (3 g/kg body weight as 25%, v/v) was administered to a group of rats by gastric-intubation twice daily for 30 days. In another group, rats were also treated with alcohol for 30 days but were then withdrawn from treatment for 30 days to assess the reversibility of ethanol-induced effects. Ethanol-induced changes in epididymal tissue and sperm glycosidases, cauda epididymal sperm motility and the fertility of rats were assessed. Ethanol treatment caused a marked decrease in the specific activities of glycosidases in both tissues and spermatozoa from epididymal segments. Cauda epididymal sperm motility and the fertility of ethanol-treated rats were significantly impaired compared to control rats fed an isocaloric diet. These changes are likely to be the consequence of direct and indirect effects of ethanol mediated through subnormal testosterone and dihydrotestosterone. Most of these changes were found to be reversible. The present study suggests that impaired activity of sperm glycosidases may be one of the factors responsible for defective sperm motility and fertilizing potential in ethanol-treated rats.

Pharmacokinetics of the ethanol bioavailability in the regenerating rat liver induced by partial hepatectomy

It is well known that a single ethanol administration is capable of inhibiting the two-thirds partial hepatectomy (PH)-induced liver regeneration (LR); nonetheless, it has not been elucidated how ethanol metabolism by the remnant liver is exerting the deleterious ethanol actions on LR. Indeed, pharmacokinetics analysis of ethanol elimination is lacking in rats subjected to PH, which might extend our understanding in the mechanisms that account for the ethanol-induced inhibition on LR after PH in the rat. Therefore, the present study is a pharmacokinetics analysis comparing intragastric and intraperitoneal administrations of ethanol to rats under PH, at several times after surgery (0 to 96 hr postsurgery). Our results show that PH rats had a much lower blood ethanol peak than sham-operated, when intragastrically administered during the first 4 hr after surgery that was transient and normalized at 6 hr post-PH. The area under the curve for blood ethanol was higher in PH animals, starting after 6 hr postsurgery and extended to the all replicative period, and returned within the control values thereafter. The quantity of ethanol absorbed after its intraperitoneal injection was essentially the same as the administered dose for all of the groups tested. Hence, ethanol bioavailability diminished due to an enhanced rate of the first-pass metabolism for ethanol in PH rats at the very early times post-PH. At later times of PH, ethanol bioavailability was practically normalized, and these effects were accompanied by a drastic increase in the liver capacity to metabolize ethanol, mainly at 48 to 96 hr after surgery, as calculated as ethanol elimination per gram of liver, as well as by total body weight. The very early changes in ethanol bioavailability in PH rats were not accounted for gastric ethanol retention in these animals. In conclusion, first-pass metabolism importantly participates in the modified ethanol bioavailability at very early times after PH, an event presumably attained to gastric catabolism of ethanol. However, the very enhanced metabolism of ethanol showed by the regenerating liver, particularly after the first 24 hr postsurgery, seems to be the main factor affecting ethanol pharmacokinetics in rats subjected to PH. The underlying mechanisms in this liver enhancement of ethanol oxidation by PH rats remains to be elucidated.

Gastritis in the alcoholic: relationship to gastric alcohol metabolism and Helicobacter pylori

Chronic gastritis is common in the alcoholic. It is characterized by histological inflammation of the gastric mucosa and is associated with variable symptomatology. Its etiology is still the subject of debate. Recently, a new alcohol dehydrogenase isoenzyme, called sigma ADH, absent from the liver but predominant in the upper GI tract, has been fully characterized, its gene cloned, and it appears to play a major role in gastric ethanol metabolism. Indeed, it has now been established, both in vivo in experimental animals and in vitro in cultured human gastric cells, that alcohol is metabolized in the gastric mucosa, resulting in the production of acetaldehyde, a toxic metabolite. In addition, Helicobacter pylori infection is common in the alcoholic, resulting in the breakdown of urea to ammonia, another toxic product. A number of studies carried out over the last 40 years revealed that antibiotic treatment eradicates ammonia production and results in histological and symptomatic improvement in the majority of patients with alcoholic gastritis. Non-invasive tests for the detection of H. pylori are now available which will facilitate the large scale studies needed to confirm whether, in H. pylori -positive patients, antibiotics should become routine treatment for alcoholic gastritis.

Gastrointestinal alcohol dehydrogenase

Alcohol dehydrogenase (ADH) consists of a family of isozymes that convert alcohols to their corresponding aldehydes using NAD+ as a cofactor. The metabolism of ethanol by gastrointestinal ADH isozymes results in the production of acetaldehyde, a highly toxic compound that binds to cellular protein and DNA if not further metabolized to acetate by acetaldehyde dehydrogenase isozymes. Acetaldehyde seems to be involved in ethanol-associated cocarcinogenesis. The metabolism of retinol and the generation of retinoic acid is a function of class I and class IV ADH, and its inhibition by alcohol may lead to an alteration of epithelial cell differentiation and cell growth and may also be involved in ethanol-associated gastrointestinal cocarcinogenesis.

Metabolism of ethanol and some associated adverse effects on the liver and the stomach

Current knowledge of alcohol oxidation and its effects on hepatic metabolism and its toxicity are summarized. This includes an evaluation of the relationship of the level of consumption to its interaction with nutrients (especially retinoids, carotenoids, and folate) and the development of various stages of liver disease. Ethanol metabolism in the stomach and its link to pathology and Helicobacter pylori is reviewed. Promising therapeutic approaches evolving from newly gained insight in the pathogenesis of medical complications of alcoholism are outlined. At present, the established approach for the prevention and treatment of alcoholism are outlined. At present, the established approach for the prevention and treatment of alcoholic liver injury is to control alcohol abuse, with the judicial application of selective antioxidant therapy, instituted at early stages, prior to the social or medical disintegration of the patient, and associated with antiinflammatory agents at the acute phase of alcoholic hepatitis. In addition, effective antifibrotic therapy may soon become available.

Gastric ethanol metabolism and gastritis: interactions with other drugs, Helicobacter pylori, and antibiotic therapy (1957-1997)--a review

The stomach provides some protection against the penetration of ethanol into the body by contributing to the metabolism of ethanol. The latter is attenuated by various drugs and, although the magnitude of this effect is still the subject of debate, patients should be warned of the corresponding possible increase in blood alcohol levels. Furthermore, oxidation of ethanol generates acetaldehyde, a toxic metabolite. In addition, chronic alcohol abuse seems to favor colonization by Helicobacter pylori, which produces ammonia that also contributes to the commonly associated chronic gastritis. Because antibiotics were shown over the last 4 decades to effectively eliminate gastric ammonia, they should be considered for the routine treatment of such chronic gastritis in the way they are now being used for ulcer therapy.

Use of measurements of ethanol absorption from stomach and intestine to assess human ethanol metabolism

Controversy exists concerning the site (stomach vs. liver) and magnitude of first-pass metabolism of ethanol. We quantitated gastric and total ethanol absorption rates in five male subjects and utilized these measurements to evaluate first-pass metabolism. Gastric emptying of ethanol (0.15 g/kg) was determined via a gamma camera and gastric absorption from the ratio of gastric ethanol to [14C]polyethylene glycol. Gastric absorption accounted for 30% and 10% of ethanol administered with food and water, respectively. With food, estimated gastric mucosal ethanol concentrations fell from 19 to 5 mM over 2 h. Calculations using these concentrations and kinetic data for gastric alcohol dehydrogenase showed <2% of the dose underwent gastric metabolism. Application of observed ethanol absorption rates to a model of human hepatic ethanol metabolism indicated that only 30% and 4% of the dose underwent first-pass metabolism when administered with food and water, respectively. We conclude that virtually all first-pass ethanol metabolism occurs in the liver and first-pass metabolism accounts for only a small fraction of total clearance.

Paradoxical effects of acute ethanolism in experimental brain injury

Acute ethanol intoxication is a frequent complicating factor in human head injury, yet its impact on neurological outcome remains poorly defined. This study was undertaken to assess the effect of varying levels of preinjury ethanol on early postinjury mortality, recovery of motor function, and degree of neural degeneration after cortical contusion injury in the rat. Adult rats were pretrained on a beam-walking task, then randomized to one of five groups: low-dose ethanol and injury (1 g/kg, 16 animals); moderate-dose ethanol and injury (2.5 g/kg, 11 animals); high-dose ethanol and injury (3 g/kg, 17 animals); no ethanol and injury (nine animals); or ethanol and sham injury (seven animals). Forty minutes after intraperitoneal injection of ethanol or saline, the rats received a pneumatic piston-induced contusion injury of the left primary motor cortex. Their beam-walking ability was assessed daily for the next 7 days. At 4 weeks postinjury, the brains were sectioned and the dimensions of the cortical lesions were determined. Preinjury ethanol administration was associated with an acute postinjury mortality rate of 29.5% (p < 0.05); the highest mortality rate (47.1%) occurred in the high-dose ethanol group, whereas no deaths occurred in the animals in the no ethanol or sham-injured groups (p < 0.01). However, injured animals receiving low- and moderate-dose ethanol had significantly less severe beam-walking impairment initially, and a more rapid return to normal beam-walking ability, compared to the no and high-dose ethanol groups (p < 0.05). Additionally, the mean lesion volumes were significantly smaller in the low- and moderate-dose ethanol treatment groups compared to the no and high-dose ethanol groups (23.2 +/- 8 mm3 and 29 +/- 6.7 mm3 vs. 52 +/- 8.8 mm3 and 53.7 +/- 10.9 mm3, respectively, p < 0.01). In this cortical contusion model, the presence of ethanol before injury appears to exert a potent neuroprotective effect when administered in low or moderate doses. This action is postulated to result from ethanol-induced inhibition of N-methyl-D-aspartate receptor-mediated excitotoxicity. The loss of neuroprotection and increased mortality rates observed with high-dose ethanol may be related to ethanol-induced hemodynamic and respiratory depression.

Effect of three different modes of alcohol administration on the activity of the rat hypothalamic-pituitary-adrenal axis

The present study compared the effect of different modes of alcohol administration on the activity of the hypothalamic-pituitary-adrenal (HPA) axis. In a first series of studies, we investigated the influence of the intraperitoneal (ip) and intragastric (ig) effect of acutely administered alcohol. Over a 3-hr period, alcohol induced dose-related increases in adrenocorticotropic hormone (ACTH) and alcohol levels in the circulation. There was a good correlation between blood ACTH and alcohol levels (ip treatment, R = 0.84; ig treatment, R = 0.79). Measurement of steady-state mRNA of the immediate early gene NGFI-B, taken as an index of neuronal activation in the paraventricular nucleus (PVN) of the hypothalamus of rats administered 3 g of alcohol/kg, indicated significant (p < 0.01) increases between 60 and 180 min after both ip and ig alcohol injection, with peak stimulation at 1 and 2 hr, respectively. Although NGFI-B mRNA levels had returned to control level in the parvicellular portion of the PVN of animals administered the drug ip 4 hr earlier, they were still significantly (p < 0.01) elevated 4 hr after ig treatment. A second series of studies used rats fed an alcohol diet containing 6.4% alcohol (w/v), or pair-fed. The rats were tested during the 4th or 6th night of treatment. Despite blood alcohol levels ranging between 0.060 and 0.140% w/v, there was no significant rise in plasma ACTH/corticosterone levels in animals fed the drug, and no detectable NGFI-B mRNA in their PVN. Collectively, these results indicate that both the ip and the ig acute injection of alcohol induced dose-related increases in plasma ACTH levels. PVN neuronal activation was also observed. In contrast, the alcohol diet had no effect on HPA hormone levels or PVN expression of NGFI-B.

Ethnic differences in gastric sigma-alcohol dehydrogenase activity and ethanol first-pass metabolism

We assessed whether the low sigma-alcohol dehydrogenase (ADH) activity in Japanese (compared with Caucasians) affects the first-pass metabolism of ethanol. ADH isozyme activities were determined in endoscopic biopsies of the gastric corpus from 24 Japanese and 41 Caucasian men by starch gel electrophoresis and by comparing the reduction of m-nitrobenzaldehyde (a preferred substrate of sigma-ADH) with that of acetaldehyde (a preferred substrate of gamma-ADH) and the glutathione-dependent formaldehyde oxidation (a specific reaction of chi-ADH). Alcohol pharmacokinetics was compared in 10 Japanese and 10 Caucasians after administration of ethanol (300 mg/kg of body weight) intravenously or orally, using 5 and 40% oral solutions. Japanese exhibited lower sigma-ADH activity than Caucasians, with no difference in the other gastric isozymes. With 5% ethanol, first-pass metabolism was strikingly lower in Japanese than in Caucasians. Blood alcohol levels were similar because of the high elimination rate in Japanese due to the hepatic beta 2-ADH variant. With 40% ethanol, the first-pass metabolism increased in both groups to comparable levels, suggesting an additional contribution by chi-ADH at high ethanol concentrations. These results indicate that sigma-ADH activity contributes significantly to gastric ethanol oxidation and its lower activity in Japanese is associated with lesser first-pass metabolism.

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.

Actions of acute ethanol intoxication on cardiopulmonary function after an endotoxin challenge

BACKGROUND

This study examined whether acute ethanol (EtOH) intoxication could alter the systemic inflammatory response evoked by endotoxin (lipopolysaccharide, LPS).

METHODS

Anesthetized (fentanyl) and mechanically ventilated mongrel pigs were administered 20% EtOH (3 gm/kg) or its vehicle (VEH) by means of gastric lavage. After 60 minutes of equilibration, blood levels were 110 to 130 mg/dl, and LPS (1 microgram/kg per 30 minutes) was infused intravenously to mimic the type of sepsis that might be encountered after a penetrating abdominal injury.

RESULTS

LPS caused initial pulmonary vasoconstriction followed by cardiovascular collapse in 7 of 14 pigs with EtOH versus 0 of 14 pigs with VEH (p = 0.0058); survival time averaged 2.4 +/- 0.5 hours for EtOH versus 4.5 +/- 0.3 hours for VEH (p = 0.002). At 3 to 5 hours after LPS infusion the survivors were acidotic (base excess, -5.1 +/- 1.5 versus 0.4 +/- 1.1 mEq/L; p = 0.007) and vasodilated (systemic vascular resistance, 54% +/- 9% versus 111% +/- 9% baseline; p = 0.005). Systemic arterial pressure and cardiac filling pressures were maintained with fluid resuscitation, but more was required for EtOH versus VEH (80 +/- 11 versus 42 +/- 5 ml/kg/hr; p = 0.0034). A diffuse capillary leak was detected with gamma scintigraphy and regional uptake of technetium 99m albumin. With EtOH versus VEH microvascular permeability was higher in abdomen (p = 0.01) and liver (p = 0.06) but not in lung (p = 0.29). These changes were probably mediated in part by leukosequestration: neutrophil counts were initially reduced more than 80% in both groups, but they then rebounded with VEH (p < 0.05) but not EtOH. The early versus late deaths within the EtOH group were distinguished by higher baseline levels of cortisol (1.4 +/- 0.3 versus 0.9 +/- 0.2 micrograms/dl; p = 0.075) and by a 50% decrease evoked by EtOH (p = 0.0042) versus no change in the late death subgroup. After LPS infusion cortisol peaked sooner and then recovered with VEH (p < 0.05), whereas the peak occurred later and there was no decay with EtOH. In addition, at 60 and 90 minutes after LPS infusion tumor necrosis factor was 119 +/- 27 and 240 +/- 40 pg/ml with VEH versus 62 +/- 15 and 95 +/- 23 pg/ml with EtOH (p = 0.041 and p = 0.0030).

CONCLUSIONS

By means of a leukocyte-mediated mechanism in the splanchnic circulation, acute EtOH impaired host defense, which exacerbated LPS-evoked systemic inflammatory response. In context with our earlier experimental study and two large clinical trials, it appears that acute EtOH can have opposite effects on the vulnerability to posttrauma sepsis, depending on the timing of the septic insult and on the immune status at the time of septic challenge.

Gastric emptying and first-pass metabolism of ethanol in elderly subjects with and without atrophic gastritis

BACKGROUND

Oral ethanol intake results in lower blood ethanol concentrations than intravenous administration of the same dose of ethanol. This first-pass metabolism is thought to be due to gastric metabolism of ethanol via alcohol dehydrogenase and also to hepatic first-pass metabolism.

METHODS

Since a loss of gastric mucosa may decrease first-pass metabolism of ethanol, this metabolism was studied in 10 elderly subjects (6 women and 4 men) with atrophic gastritis and bacterial overgrowth and in 17 control subjects with normal gastric secretory function. Atrophic gastritis was verified by means of the serum pepsinogen I to pepsinogen II ratio and the hypochlorhydria occurring after pentagastrin stimulation. Bacterial overgrowth was assessed by bacteria. In addition, gastric emptying rates of ethanol solution with technetium-99m sulfur colloid were calculated from scintigraphic images. Furthermore, gastric biopsy specimens were taken from 12 female patients with atrophic gastritis and from 12 controls for determination of alcohol dehydrogenase activity.

RESULTS

Neither gender (female versus male, 28 +/- 5% versus 42 +/- 5%), atrophic gastritis (normal versus atrophic gastritis, 35 +/- 4% versus 32 +/- 6%), nor tetracycline treatment in atrophic gastritis subjects (before versus after, 32 +/- 6% versus 41 +/- 5%) had a statistically significant effect on the first-pass metabolism of ethanol in the elderly. Gastric alcohol dehydrogenase activity was significantly lower in atrophic gastritis subjects than in controls (p < 0.01). A significant correlation was found between the first-pass metabolism of ethanol in healthy controls and gastric half-emptying time (p = 0.032).

CONCLUSIONS

We conclude from these data that the rate of gastric emptying modulates first-pass metabolism of ethanol in elderly individuals.

Acute ethanol intoxication and endotoxemia after trauma

To determine actions of acute intoxication on pathophysiologic responses to trauma, anesthetized and ventilated mongrel pigs received a 20% solution of ethanol (EtOH) by an intravenous (IV group; 2 g/kg, n = 8) or an oral (PO group; 3 g/kg, n = 12 x 60 minutes) route of administration, or the lactated Ringer's vehicle (LR group; n = 12). After 60 minutes, all were subjected to soft tissue injury and 30 to 35% hemorrhage, 60-minute shock, and then resuscitation, with shed blood plus supplemental LR. After 3 days, host defense was challenged with Escherichia coli lipopolysaccharide (LPS); (1 microgram/kg x 30-minutes IV). The supplemental resuscitation was identical (50-53 mL/kg/hours), but posttraumatic acidosis was observed in the IV group and the PO group (base deficit = 4.4 +/- 1.3 and 5.5 +/- 0.9 mEq/L) and not in the LR group. After 3 days, the acid-base equilibrium was restored, but a difference in host defense was unmasked by LPS. In the LR group, LPS-evoked pulmonary vasoconstriction was followed by decreased compliance and ventilation-perfusion mismatch, which was associated at 3 to 5 hours with a base deficit, reduced SVO2, and reduced PO2 (-0.5 +/- 0.2 mEq/L, 46 +/- 1%, 127 +/- 1 mm Hg). These changes were blunted in the PO group (2.0 +/- 0.1 mEq/L, 56 +/- 1%, 183 +/- 4 mm Hg) and potentiated in the IV group (-4.3 +/- 0.5 mEq/L, 40 +/- 2%, 60 +/- 2 mm Hg), even though more fluid was required to maintain systemic arterial and cardiac filling pressures following LPS administration in the IV (40 +/- 6 mL/kg/ hours) versus the LR or PO groups (31 +/- 5 or 23 +/- 3). The PO versus LR differences could not be attributed to enteral nutrition because an isocaloric solution of 50% dextrose had no effect versus LR solution. EtOH caused neutropenia following trauma, relative to LR solution, but the IV versus PO differences could not be discriminated on the basis of neutrophil or lymphocytes counts, nor CD18 receptor expression, nor renal or hepatic dysfunction. However, T4 lymphocytes and cortisol, a nonspecific index of inflammation, were higher for at least 24 hours after trauma with IV, relative to PO or LR. Blood EtOH was similar with IV or PO during resuscitation (100-120 mg/dL), but the kinetics were different prior to trauma. With PO, blood EtOH slowly accumulated to a steady state plateau, the level of which was higher with no anesthesia or no trauma. With IV, blood EtOH peaked at 275 mg/dL and then exponentially declined with a rate that was not influenced to a major extent by trauma or by anesthesia. Therefore: 1) EtOH absorption is impaired during trauma (in part because of reduced gut blood flow); 2) acute EtOH intoxication at the time of trauma altered neutrophils, plasma cortisol, and T4 lymphocytes during recovery and host defense to a superimposed LPS challenge. The apparently favorable effect of PO versus IV EtOH on the response to endotoxemia after trauma probably reflects differences in the kinetics of blood EtOH in the interval before reperfusion but a "first pass" effect (metabolism in the gut or liver) might also explain the data.

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.