Pharmacokinetics of ethanol: a review of the methodology

Pharmacological activators of ALDH2: A new strategy for the treatment of alcohol use disorders

In mammals, ethanol is metabolized to acetaldehyde mainly by the liver alcohol dehydrogenase (ADH), and acetaldehyde is subsequently oxidized to acetate by mitochondrial aldehyde dehydrogenase (ALDH2). The presence of an inactive variant of ALDH2 or the use of inhibitors of this enzyme leads to an accumulation of acetaldehyde after ethanol consumption, generating an aversive reaction that inhibits subsequent alcohol intake. However, experimental evidence shows that acetaldehyde has potent rewarding effects at the central level, suggesting that acetaldehyde would be responsible for the addictive effect of alcohol. Alda-1 is an organic molecule that acts as a pharmacological activator of ALDH2. Studies in animal models of alcohol use disorders (AUD; i.e. alcoholism) have shown that Alda-1 can inhibit the acquisition, the chronic intake, and the relapse of alcohol consumption. These effects are reversible without any effects on water consumption or other natural reinforcer such as saccharin. It has also been reported that Alda-1 can act as a protective agent from the toxic effects on various tissues and organs mediated by ethanol-derived acetaldehyde, including liver damage, cancer, and central nervous system (CNS) alterations. Using in silico tools such as molecular docking the identification of important molecular interactions between Alda-1 and ALDH2 has been demonstrated, identifying new molecules with higher pharmacological features. Thus, there is now preclinical evidence supporting the use of activators of ALDH2 as a pharmacological strategy for the treatment of AUD.

Effects of Hovenia dulcis fruit and peduncle extract on alcohol metabolism

ETHNOPHARMACOLOGICAL RELEVANCE

The dried fruit and peduncle of Hovenia dulcis Thunberg (Rhamnaceae) (HD) has been used as a folk medicine to treat liver disease, detoxify alcoholism, and prevent and cure hangovers.

AIM OF THE STUDY

We investigated the pharmacology of HD on the kinetics of EtOH and on the enzymes related to alcohol metabolism to seek the scientific evidence of HD to prevent hangover, the effectiveness as a folk medicine.

MATERIALS AND METHODS

EtOH was orally administered 30 min after oral administration of HD boiling water extract in rats. Then, the profiles of blood EtOH concentrations were measured. Mice were reared with food containing powdered HD for 7 days, and the activities of alcohol dehydrogenase (ADH) and acetaldehyde dehydrogenase (ALDH) in liver were measured. Hepa1c1c7 cells were cultured with the medium containing HD extract, and the activities of ADH and ALDH were measured.

RESULTS

HD extract reduced the blood EtOH concentrations in rats and induced the activities of ADH and ALDH and mRNA and protein expressions of ADH1B, ALDH1A1, and ALDH2 in the liver of mice and Hepa1c1c7 cells. Dihydromyricetin, one of the ingredients of HD, significantly induced the activities of ADH and ALDH in Hepa1c1c7 cells, however, the fractions containing hydrophilic organic compounds with small molecular weight contributed the most of the activities of HD extract.

CONCLUSIONS

We clarified the experimental pharmacological evidences of HD as a folk medicine to detoxify alcoholism and prevent hangovers.

Could Alcohol Abuse and Dependence on Junk Foods Inducing Obesity and/or Illicit Drug Use Represent Danger to Liver in Young People with Altered Psychological/Relational Spheres or Emotional Problems?

Recent data show that young people, mainly due to the pressure of some risk factors or due to disrupted interpersonal relationships, utilise greater reward value and display greater sensitivity to the reinforcing properties of “pleasurable stimuli”, specifically in those situations in which an enhanced dopamine release is present. Alcoholic beverages, foods rich in sugar and fat, and illicit drug use are pleasurable feelings associated with rewards. Research shows that there is a link between substance abuse and obesity in brain functioning. Still, alcohol excess is central in leading to obesity and obesity-related morbidities, such as hepatic steatosis, mainly when associated with illicit drug dependence and negative eating behaviours in young people. It is ascertained that long-term drinking causes mental damage, similarly to drug abuse, but also affects liver function. Indeed, beyond the pharmacokinetic interactions of alcohol with drugs, occurring in the liver due to the same metabolic enzymes, there are also pharmacodynamic interactions of both substances in the CNS. To complicate matters, an important noxious effect of junk foods consists of inducing obesity and obesity-related NAFLD. In this review, we focus on some key mechanisms underlying the impact of these addictions on the liver, as well as those on the CNS.

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.

A comprehensive review of cytochrome P450 2E1 for xenobiotic metabolism

Cytochrome P450 2E1 (CYP2E1) plays a vital role in drug-induced hepatotoxicity and cancers (e.g. lung and bladder cancer), since it is responsible for metabolizing a number of medications and environmental toxins to reactive intermediate metabolites. CYP2E1 was recently found to be the highest expressed CYP enzyme in human livers using a proteomics approach, and CYP2E1-related toxicity is strongly associated with its protein level that shows significant inter-individual variability related to ethnicity, age, and sex. Furthermore, the expression of CYP2E1 demonstrates regulation by extensive genetic polymorphism, endogenous hormones, cytokines, xenobiotics, and varying pathological states. Over the past decade, the knowledge of pharmacology, toxicology, and biology about CYP2E1 has grown remarkably, but the research progress has yet to be summarized. This study presents a timely systematic review on CYP2E1's xenobiotic metabolism, genetic polymorphism, and inhibitors, with the focus on their clinical relevance for the efficacy and toxicity of various CYP2E1 substrates. Moreover, several knowledge gaps have been identified towards fully understanding the potential interactions among different CYP2E1 substrates in clinical settings. Through in-depth analyses of these knowns and unknowns, we expect this review will aid in future drug development and improve management of CYP2E1 related clinical toxicity.

Activation of mitochondrial aldehyde dehydrogenase (ALDH2) by ALDA-1 reduces both the acquisition and maintenance of ethanol intake in rats: A dual mechanism?

A number of pre-clinical studies have shown that brain-generated acetaldehyde, the first metabolite of ethanol, exerts reinforcing effects that promote the acquisition of ethanol intake, while chronic intake maintenance appears to be mediated by alcohol-induced brain neuroinflammation/oxidative stress. Recently, it was described that N-(1,3-benzodioxol-5-ylmethyl)-2,6-dichlorobenzamide (ALDA-1) activates aldehyde dehydrogenase-2 (ALDH2), enzyme that catalyzes the oxidation of ethanol-derived acetaldehyde to acetate. The aim of this study was to determine the effects of ALDA-1 on both the acquisition and the maintenance of alcohol intake in alcohol-preferring UChB rats. For ethanol acquisition studies, naïve UChB rats were treated with five daily doses of ALDA-1 (12.5, 25 or 50 mg/kg, i.p.) from one day before the start of ethanol exposure. For chronic intake studies, UChB rats exposed for 98 days to a free access to 10% ethanol and water were treated daily with ALDA-1 (12.5, 25 or 50 mg/kg, i.p.) for five days. The administration of ALDA-1 reduced by 72-90% (p < 0.001) the acquisition of ethanol consumption in naïve rats. At chronic ethanol consumption, ALDA-1 reduced ethanol intake by 61-82% (p < 0.001). ALDA-1 administration increased by 3- and 2.3-fold the activity of ALDH2 in brain and liver, respectively. ALDA-1 did not affect saccharin consumption, nor it modified the rate of ethanol elimination. The study shows that the activation of ALDH2 by ALDA-1 is effective for inhibiting both the acquisition and the maintenance of chronic ethanol intake by alcohol-preferring rats. Thus, the activation of brain ALDH2 may constitute a novel approach in the treatment of alcohol use disorders.

Measurement of Mood States Following Light Alcohol Consumption: Evidence from the Implicit Association Test

As the problems of mood measurements during alcohol consumption of alcoholic beverages do not necessarily evoke interpretable physiological responses, explicit reports may be contaminated by various cognitive biases or expectations. The present study examined whether emotional responses induced by the consumption of beverages containing low concentrations of alcohol can be measured using the Implicit Association Test (IAT). The IAT can detect the estimates of internal proximity between bipolar target concepts (e.g., cheerfulness and fatigue). Participants (N = 30) received three IAT sessions, followed by drinking a beverage containing 0% (control), 1%, or 3% alcohol by volume, and three IATs (at 0, 30, and 60 min after the time of consumption). We also recorded the explicit responses regarding the extent of drunkenness. The analyses of variance with alcohol concentration and time reveal dissociation between implicit and explicit measures. The IAT scores under the alcohol conditions reflect a more cheerful mood state relative to the baseline test. This effect of enhanced cheerfulness was not observed under the non-alcohol control condition. These results demonstrate that the impact of the consumption of low-alcohol beverages on mood can be measured using the IAT.

Alcohol-Derived Acetaldehyde Exposure in the Oral Cavity

Alcohol is classified by the International Agency for Research on Cancer (IARC) as a human carcinogen and its consumption has been associated to an increased risk of liver, breast, colorectum, and upper aerodigestive tract (UADT) cancers. Its mechanisms of carcinogenicity remain unclear and various hypotheses have been formulated depending on the target organ considered. In the case of UADT cancers, alcohol's major metabolite acetaldehyde seems to play a crucial role. Acetaldehyde reacts with DNA inducing modifications, which, if not repaired, can result in mutations and lead to cancer development. Despite alcohol being mainly metabolized in the liver, several studies performed in humans found higher levels of acetaldehyde in saliva compared to those found in blood immediately after alcohol consumption. These results suggest that alcohol-derived acetaldehyde exposure may occur in the oral cavity independently from liver metabolism. This hypothesis is supported by our recent results showing the presence of acetaldehyde-related DNA modifications in oral cells of monkeys and humans exposed to alcohol, overall suggesting that the alcohol metabolism in the oral cavity is an independent cancer risk factor. This review article will focus on illustrating the factors modulating alcohol-derived acetaldehyde exposure and effects in the oral cavity.

Time Delays in Transdermal Alcohol Concentrations Relative to Breath Alcohol Concentrations

AIMS

Monitors of transdermal alcohol concentration (TAC) provide an objective measurement of alcohol consumption that is less invasive than measurements in blood, breath or urine; however, there is a substantial time delay in the onset of TAC compared to blood or breath alcohol concentrations (BrACs). The current study examined the characteristics of the delay between peak TAC and peak BrAC.

METHODS

Data was aggregated from three experimental laboratory studies (N = 61; 32 men, 29 women) in which participants wore a TAC monitor and BrAC was monitored while drinking one, two, three, four and five beers in the laboratory. Analyses examined the sex- and dose-related differences in peak BrAC and TAC, the time-to-peak BrAC and TAC, and time lag between the peak BrAC and TAC values.

RESULTS

The times-to-peak were an increasing function of the number of beers consumed. At each level of beer consumption the peak TAC averaged lower than peak BrAC and times-to-peak TAC were longer than for BrAC. The time-to-peak BrAC and TAC was longer for women than men. The congruence between peak TAC and BrAC increased as a function of the beers consumed. No sex difference in the time lag between peak BrAC and TAC was detected.

CONCLUSIONS

The congruence between TAC and BrAC and time lags between TAC and BrAC are related to the number of beers consumed. Peak values of TAC and BrAC became more congruent with higher doses but the time lag increased as a function of the amount of alcohol consumed.

SHORT SUMMARY

The time delay (or lag) and congruence between transdermal vs. BrACs increases as the number of beers increases. Though sex differences are evident in peak transdermal and BrACs, no sex differences were evident in the time lag and the congruence between transdermal and breath alcohol concentrations.

Best-practices approach to determination of blood alcohol concentration (BAC) at specific time points: Combination of ante-mortem alcohol pharmacokinetic modeling and post-mortem alcohol generation and transport considerations

Alcohol concentrations in biological matrices offer information regarding an individual's intoxication level at a given time. In forensic cases, the alcohol concentration in the blood (BAC) at the time of death is sometimes used interchangeably with the BAC measured post-mortem, without consideration for alcohol concentration changes in the body after death. However, post-mortem factors must be taken into account for accurate forensic determination of BAC prior to death to avoid incorrect conclusions. The main objective of this work was to describe best practices for relating ante-mortem and post-mortem alcohol concentrations, using a combination of modeling, empirical data and other qualitative considerations. The Widmark modeling approach is a best practices method for superimposing multiple alcohol doses ingested at various times with alcohol elimination rate adjustments based on individual body factors. We combined the selected ante-mortem model with a suggestion for an approach used to roughly estimate changes in BAC post-mortem, and then analyzed the available data on post-mortem alcohol production in human bodies and potential markers for alcohol production through decomposition and putrefaction. Hypothetical cases provide best practice approaches as an example for determining alcohol concentration in biological matrices ante-mortem, as well as potential issues encountered with quantitative post-mortem approaches. This study provides information for standardizing BAC determination in forensic toxicology, while minimizing real world case uncertainties.

Pharmacokinetic and pharmacodynamic drug interactions with ethanol (alcohol)

Ethanol (alcohol) is one of the most widely used legal drugs in the world. Ethanol is metabolized by alcohol dehydrogenase (ADH) and the cytochrome P450 (CYP) 2E1 drug-metabolizing enzyme that is also responsible for the biotransformation of xenobiotics and fatty acids. Drugs that inhibit ADH or CYP2E1 are the most likely theoretical compounds that would lead to a clinically significant pharmacokinetic interaction with ethanol, which include only a limited number of drugs. Acute ethanol primarily alters the pharmacokinetics of other drugs by changing the rate and extent of absorption, with more limited effects on clearance. Both acute and chronic ethanol use can cause transient changes to many physiologic responses in different organ systems such as hypotension and impairment of motor and cognitive functions, resulting in both pharmacokinetic and pharmacodynamic interactions. Evaluating drug interactions with long-term use of ethanol is uniquely challenging. Specifically, it is difficult to distinguish between the effects of long-term ethanol use on liver pathology and chronic malnutrition. Ethanol-induced liver disease results in decreased activity of hepatic metabolic enzymes and changes in protein binding. Clinical studies that include patients with chronic alcohol use may be evaluating the effects of mild cirrhosis on liver metabolism, and not just ethanol itself. The definition of chronic alcohol use is very inconsistent, which greatly affects the quality of the data and clinical application of the results. Our study of the literature has shown that a significantly higher volume of clinical studies have focused on the pharmacokinetic interactions of ethanol and other drugs. The data on pharmacodynamic interactions are more limited and future research addressing pharmacodynamic interactions with ethanol, especially regarding the non-central nervous system effects, is much needed.

Ethanol pharmacokinetics in neonates and infants

Introduction

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

Materials and methods

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

Results

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

Conclusions

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

Alcohol metabolism

This article describes the pathways and factors that modulate blood alcohol levels and metabolism and describes how the body disposes of alcohol. The various factors that play a role in the distribution of alcohol in the body, influence the absorption of alcohol, and contribute to first-pass metabolism of alcohol are described. Most alcohol is oxidized in the liver, and general principles and overall mechanisms for alcohol oxidation are summarized. The kinetics of alcohol elimination in-vivo and the various genetic and environmental factors that can modify the rate of alcohol metabolism are discussed.

Phytotherapy of Alcoholism

Alcoholism is a medical, social, and economic problem where treatment methods mostly include difficult and long-lasting psychotherapy and, in some cases, quite controversial pharmacological approaches. A number of medicinal plants and pure natural compounds are reported to have preventive and therapeutic effects on alcoholism and alcohol dependency, but their constituents, efficacy and mechanism of action are mostly unknown so far. Recently, kudzu [ Pueraria lobata (Willd.) Ohwi], St. John's wort ( Hypericum perforatum L.), danshen ( Salvia miltiorrhiza Bge.), ginseng ( Panax ginseng C.A. Mey.), Japanese raisin tree ( Hovenia dulcis Thunb.), ibogaine ( Tabernanthe iboga H. Bn.), evening primrose ( Oenothera biennis L.), prickly pear fruit ( Opuntia ficus indica (L.) Mill.), purple passionflower ( Passiflora incarnata L.), thyme ( Thymus vulgaris L.), fenugreek seed ( Trigonella foenum-graecum L.), ginger ( Zingiber officinale Roscoe) and many others drew the attention of researchers. Can, therefore, drugs of natural origin be helpful in the treatment of alcoholism or in decreasing alcohol consumption?

In silico Models of Alcohol Dependence and Treatment

In this paper we view alcohol dependence and the response to treatment as a recurrent bio-behavioral process developing in time and propose formal models of this process combining behavior and biology in silico. The behavioral components of alcohol dependence and treatment are formally described by a stochastic process of human behavior, which serves as an event generator challenging the metabolic system. The biological component is driven by the biochemistry of alcohol intoxication described by deterministic models of ethanol pharmacodynamics and pharmacokinetics to enable simulation of drinking addiction in humans. Derived from the known physiology of ethanol and the literature of both ethanol intoxication and ethanol absorption, the different models are distilled into a minimal model (as simple as the complexity of the data allows) that can represent any specific patient. We use these modeling and simulation techniques to explain responses to placebo and ondansetron treatment observed in clinical studies. Specifically, the response to placebo was explained by a reduction of the probability of environmental reinforcement, while the effect of ondansetron was explained by a gradual decline in the degree of ethanol-induced neuromodulation. Further, we use in silico experiments to study critical transitions in blood alcohol levels after specific average number of drinks per day, and propose the existence of two critical thresholds in the human - one at 5 and another at 11 drinks/day - at which the system shifts from stable to critical and to super critical state indicating a state of alcohol addiction. The advantages of such a model-based investigation are that (1) the process of instigation of alcohol dependence and its treatment can be deconstructed into meaningful steps, which allow for individualized treatment tailoring, and (2) physiology and behavior can be quantified in different (animal or human) studies and then the results can be integrated in silico.

First-order alcohol elimination in severe alcohol intoxication in an adolescent: a case report

We report a case of severe ethanol intoxications in a 14-year-old boy whose starting blood alcohol concentration was 490 mg/dL. The intoxication led to coma with hypoventilation, hypoxemia, hypothermia, and a life-threatening situation. Elimination of ethanol followed nonlinear first-order concentration-dependent pharmacokinetics. Fluid balance was disturbed because of marked diuresis, and respirator treatment was needed. The treatment of fluid balance and the risk of hypoxemia in severe alcohol poisoning are emphasized.

Physiologically based pharmacokinetic (PBPK) models for ethanol

Physiologically based pharmacokinetic models have been used to describe the distribution and elimination of ethanol after intravenous administration. These models have been used to estimate the ethanol infusion profile that is sufficient for achieving a prescribed breath ethanol concentration time course in individuals, providing a useful platform for several pharmacokinetic and pharmacodynamic investigations. Mathematical foundations of these models are examined, including the derivation of an explicit set of governing equations in the form of a system of nonlinear ordinary differential equations. These equations can then be used to formulate and refine parameter identification and control strategies. Finally, a framework in which models related to this model can be constructed and analyzed is described.

Effect of opioid substitution therapy on alcohol metabolism

Forty opioid substitution patients (methadone, n = 14; LAAM, n = 14; and buprenorphine, n = 12) who were participating in a study on the impact of opiate substitution treatment on driving ability and 22 non-opiate-using control subjects were administered 14.7 g/70 kg of alcohol in two separate sessions, one 2-3 hours before opioid pharmacotherapy dosing and the other 1-2 hours after dosing. The mean blood alcohol concentration (BAC) in the post-opioid dose session was significantly lower than that in the pre-opioid dose session (p < .05). There was a significant effect of experimental group (LAAM, methadone, buprenorphine, or control) on BAC in sessions conducted 1-2 hours after the opioid substitution dose (p < .01). There was a trend for a reduced effect of experimental group on BAC in the pre-opioid substitution dose session (p = .06). The BAC of non-opioid substitution control subjects was significantly higher than that of the LAAM (before and after LAAM dosing) and methadone (after methadone dosing; p < .05) patients. These findings provide evidence for the first time of an interaction between opiates and alcohol in humans that is strongest at the time of peak opiate plasma levels in the hours after opioid dosing.

Gelatin "Shots" as a New Method for Alcohol Administration in a Laboratory Setting

BACKGROUND

This experiment was designed to compare gelatin "shots"-a new procedure for administering alcohol in a laboratory setting-to the alcohol beverage method. We proceeded to test whether the two methods were comparable in terms of alcohol absorption, metabolism, and effects on mood and whether gelatin "shots" were better than the beverage in disguising alcohol in a blind, placebo comparison.

METHODS

Healthy volunteers participated in a two-phase trial. In the first phase they completed 2 days of testing during which the effects of alcohol-delivered in beverage (1 day) or gelatin "shots" (alternative day)-on blood and breathalyzer concentrations and mood were assessed. In the second phase participants completed 2 days of testing and were asked to identify if samples contained alcohol or placebo. The presentation of alcohol and placebo and the presentation of beverage or gelatin "shots" were random.

RESULTS

In the first phase there was a significant time-by-condition interaction in the blood alcohol concentration. Two-and-a-half hours after the alcohol was administered, those given gelatin "shots" had slightly lower but statistically significant blood alcohol concentrations. There was a significant time effect for breathalyzer alcohol levels but no condition or condition-by-time interaction. There were no differences between the two methods on any of the subjective mood measures. In the second phase of the study there were differences in the ability to differentiate alcohol from placebo between the two conditions with significantly more participants making errors in the gelatin "shots" than in the beverage condition.

CONCLUSIONS

Our findings indicate that gelatin "shots" are an effective method for delivering alcohol to humans in a laboratory setting. This method may be superior to the alcohol beverage mixture in a placebo-controlled design because gelatin "shots" mask the alcohol much better than a beverage and are easier to administer.

Dissociation between the locomotor and anxiolytic effects of acetaldehyde in the elevated plus-maze: evidence that acetaldehyde is not involved in the anxiolytic effects of ethanol in mice

Acetaldehyde, the first product of ethanol metabolism, has been suggested to play a major role in many behavioral effects of ethanol. However, very few studies have directly tested the behavioral effects of the acute administration of acetaldehyde. In particular, the role of this metabolite in ethanol-induced anxiolytic effects has never been extensively tested. The aim of the present study was to characterize the anxiolytic effects of acetaldehyde in two strains of mice, C57BL/6J and CD1 mice with the elevated plus-maze procedure. The results show that acute injections of ethanol (1-2 g/kg) induced significant dose-dependent anxiolytic effects in both strains of mice. In contrast, acetaldehyde failed to produce any anxiolytic effect, although it induced a significant hypolocomotor effect at the highest doses. In an independent experiment, cyanamide, an aldehyde dehydrogenase inhibitor, prevented the locomotor stimulant effects of ethanol, although it failed to alter its anxiolytic effects. Together, the results of the present study indicate that acetaldehyde is not involved in ethanol-induced anxiolytic effects, although it may be involved in its sedative/hypolocomotor effects.

Ethanol rapidly causes activation of JNK associated with ER stress under inhibition of ADH

Acute ethanol loading causes oxidative stress to activate cell-death signaling via c-Jun NH2-terminal kinase (JNK) in livers. JNK are stimulated under conditions of endoplasmic reticulum (ER) stress which causes programmed cell death. However, no remarked cell death was observed in acute ethanol intoxication. Akt, one of the cell survival protein kinases, may be activated under ethanol loading. The aim of this study was to estimate activation of JNK and ER stress, role of ethanol metabolism on the activation, and association of JNK with Akt under acute ethanol loading using the perfused rat liver system. Activation of JNK or Akt and association of JNK and Akt with JNK interacting protein 1 were estimated by immunoprecipitation and immunoblotting. Expression of 78 kDa glucose-regulated protein (GRP78) mRNA, a biomarker of ER stress, was detected by quantitative real-time RT-PCR. Activations of JNK and Akt were enhanced by co-treatment with ethanol and a classical inhibitor of alcohol dehydrogenase (ADH). Addition of an antioxidant reduced the activation of JNK. Ethanol loading with ADH inhibition causes down-regulation of GRP78 mRNA levels. Therefore, these findings suggest first revelation that inhibition of ethanol metabolism complicates oxidative and ER stresses produced by ethanol.

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.

Med-psych drug-drug interactions update. Antiretrovirals, part III: antiretrovirals and drugs of abuse

The third in a series reviewing the HIV/AIDS antiretroviral drugs, this report summarizes the interactions between antiretrovirals and common drugs of abuse. In an overview format for primary care physicians and psychiatrists, the metabolism and drug interactions in the context of antiretroviral therapy are presented for the following drugs of abuse: alcohol, benzodiazepines, cocaine, GHB (liquid X), ketamine (special K), LSD (acid), MDMA (Ecstasy), opiates, PCP (angel dust), and THC (marijuana).

Voluntary alcohol intake in two rat lines selectively bred for learned helpless and non-helpless behavior

RATIONALE

A high comorbidity between depression and alcoholism has been reported in several studies, but the mechanisms underlying this relationship remain unknown.

OBJECTIVES

We tested whether learned helplessness in rats as a model for depression is associated with enhanced alcohol intake and relapse behavior.

METHODS

Congenital learned helplessness (cLH) and congenital non-learned helplessness (cNLH) rats were selectively bred for differences in an escape paradigm. Sucrose preference was tested at the first hour of the dark phase. In order to study an association with alcohol drinking behavior, rats underwent a free-choice procedure with access to water, and 5% and 20% alcohol solutions for 6 weeks. After acquisition of alcohol drinking behavior, the alcohol deprivation effect (ADE) was assessed. Sensitivity to the sedative-hypnotic effect of alcohol was measured by loss of the righting reflex.

RESULTS

cLH rats showed significantly lower preference for sucrose solutions during the second half hour of the dark phase than cNLH rats. Alcohol intake of male cLH rats was not significantly different from that of male cNLH rats. In contrast, cLH female rats consumed higher amounts of alcohol than female cNLH rats. The ADE was more pronounced in female animals, although the magnitude of the ADE was similar in both cNLH and cLH female rats. The time to regain the righting reflex was significantly higher in both male and female cLH rats than in cNLH rats.

CONCLUSIONS

In summary, these data suggest that an inborn depressive-like behavior in female rats is associated with enhanced alcohol intake.

The metabolism of nonane, a JP-8 jet fuel component, by human liver microsomes, P450 isoforms and alcohol dehydrogenase and inhibition of human P450 isoforms by JP-8

Nonane, a component of jet-propulsion fuel 8 (JP-8), is metabolized to 2-nonanol and 2-nonanone by pooled human liver microsomes (pHLM). Cytochrome P450 (CYP) isoforms 1A2, 2B6 and 2E1 metabolize nonane to 2-nonanol, whereas alcohol dehydrogenase, CYPs 2B6 and 2E1 metabolize 2-nonanol to 2-nonanone. Nonane and 2-nonanol showed no significant effect on the metabolism of testosterone, estradiol or N,N-diethyl-m-toluamide (DEET), but did inhibit carbaryl metabolism. JP-8 showed modest inhibition of testosterone, estradiol and carbaryl metabolism, but had a more significant effect on the metabolism of DEET. JP-8 was shown to inhibit CYPs 1A2 and 2B6 mediated metabolism of DEET, suggesting that at least some of the components of JP-8 might be metabolized by CYPs 1A2and/or 2B6.

Assessment of UDP-glucuronosyltransferase catalyzed formation of ethyl glucuronide in human liver microsomes and recombinant UGTs

While ethanol is primarily metabolized to acetaldehyde and acetic acid via alcohol dehydrogenase, a minor but increasingly important pathway in the field of forensic science involves the conjugation of glucuronic acid to form an ethyl glucuronide (EtG) metabolite. The kinetics of ethyl glucuronide formation were examined in human liver microsomes (HLM) and recombinant UDP-glucuronosyltransferases (UGTs). The metabolite exhibited a relatively slow rate of formation in a human liver microsome mix of 75.4 pmol/(min/mg). Further investigation identified multiple UGT isoforms to be responsible for catalyzing the addition of glucuronic acid to ethanol, with UGT1A1 and 2B7 being the two most prevalent isoforms. Co-incubation with bilirubin or 3'-azido-3'-deoxythymidine (UGT1A1 and 2B7 inhibitors, respectively) inhibited the greatest amount of ethyl glucuronide formation, though other UGT inhibitors also showed some effect. Enzyme kinetics were performed in human liver microsomes and recombinant UGT enzymes. The apparent Km (Km app) and Vmax values were determined to be 0.17+/-0.08 mM and 75.98+/-5.63 pmol/(min/mg) (human liver microsomes), 0.03+/-0.01 mM and 25.22+/-3.45 pmol/(min/mg) (UGT1A1), and 0.11+/-0.04 mM and 52.03+/-9.8 pmol/(min/mg) (UGT2B7). Thus, it appears that multiple UGTs are responsible for the formation of ethyl glucuronide and that any functional differences in the enzymology underlying ethyl glucuronide formation would most likely be masked by a combination of other enzymatic pathways.

The clock gene Per2 influences the glutamatergic system and modulates alcohol consumption

Period (Per) genes are involved in regulation of the circadian clock and are thought to modulate several brain functions. We demonstrate that Per2(Brdm1) mutant mice, which have a deletion in the PAS domain of the Per2 protein, show alterations in the glutamatergic system. Lowered expression of the glutamate transporter Eaat1 is observed in these animals, leading to reduced uptake of glutamate by astrocytes. As a consequence, glutamate levels increase in the extracellular space of Per2(Brdm1) mutant mouse brains. This is accompanied by increased alcohol intake in these animals. In humans, variations of the PER2 gene are associated with regulation of alcohol consumption. Acamprosate, a drug used to prevent craving and relapse in alcoholic patients is thought to act by dampening a hyper-glutamatergic state. This drug reduced augmented glutamate levels and normalized increased alcohol consumption in Per2(Brdm1) mutant mice. Collectively, these data establish glutamate as a link between dysfunction of the circadian clock gene Per2 and enhanced alcohol intake.