How to antagonize ethanol-induced inebriation

The effects of ethanol in combination with the alpha 2-adrenoceptor agonist dexmedetomidine and the alpha 2-adrenoceptor antagonist atipamezole on brain monoamine metabolites and motor performance of mice

The time course of the effects of ethanol alone and in combination with the selective alpha 2-adrenoceptor agonist dexmedetomidine and the alpha-adrenoceptor antagonist atipamezole was studied in NIH-Swiss mice. Core body temperature, rotarod performance, motility and changes in the noradrenaline, dopamine, and 5-hydroxytryptamine (5-HT) metabolite contents of different brain parts (limbic forebrain, striatum, lower brainstem, the rest of the forebrain + midbrain and hypothalamus) were measured. Atipamezole (3 mg/kg) attenuated the hypothermia induced by either ethanol (3 g/kg) alone or ethanol in combination with dexmedetomidine (0.3 mg/kg). Atipamezole shortened the duration of the ethanol-impaired and ethanol + dexmedetomidine-impaired rotarod performance. Further, atipamezole prevented the decreased motility due to the combined treatment with ethanol and dexmedetomidine. Ethanol increased 3-methoxy-4-hydroxyphenylethylene glycol (MHPG), homovanillic acid (HVA) and 3,4-dihydroxyphenylacetic acid (DOPAC) values. Dexmedetomidine alone decreased MHPG and 5-hydroxyindoleacetic acid (5-HIAA) concentrations and increased DOPAC and HVA values. Dexmedetomidine combined with ethanol resulted in a further increase in DOPAC and HVA values. Pharmacokinetic parameters did not contribute to this antagonism of ethanol's effects by atipamezole, nor did the antagonism observed in rotarod performance or hypothermia seem to correlate with the changes seen in the brain noradrenaline and dopamine or 5-HT metabolism. In conclusion, these findings suggest that several ethanol effects are not mediated via direct activation of alpha 2-adrenoceptors, even though some of ethanol's behavioral and physiological effects may be antagonized by coadministration of alpha 2-adrenoceptor antagonists.

Intravenous pyridoxine in acute ethanol intoxication

Intravenous pyridoxine was evaluated as an agent for the reversal of ethanol-induced central nervous depression in a randomised double blind controlled study of 108 patients presenting with a clinical diagnosis of acute ethanol intoxication to two accident and emergency departments. Level of consciousness, measured by a modified Glasgow coma scale, showed no significant change after a single 1 g dose of intravenous pyridoxine when compared to controls given saline. The mean fall in blood alcohol concentration after one hour was 33 mg dl-1 (7.2 mmol l-1) in both groups suggesting that pyridoxine has no antidotal action and no short term effect on the rate of metabolism of ethanol.

Ethanol antagonism by atipamezole on motor performance in mice

The interactions of an alpha 2-adrenoceptor antagonist, atipamezole, and an alpha 2-adrenoceptor agonist, dexmedetomidine, with ethanol were studied in male NIH Swiss mice. The mice were given (i.p.) atipamezole 0.1, 0.3, 1, 3 and 10 mg/kg and dexmedetomidine 0.01, 0.03, 0.1, 0.3, 1, 3 and 10 mg/kg; the ethanol doses were 1, 2 or 3 g/kg. Motor performance was measured by spontaneous locomotor activity and rotarod test. Dexmedetomidine impaired performance in both tests. The effect of dexmedetomidine peaked at the dose of 1 mg/kg. Three mg/kg of atipamezole abolished totally the effects of 0.3 mg/kg of dexmedetomidine and partially those of 1 mg/kg of dexmedetomidine. Atipamezole counteracted and dexmedetomidine enchanced ethanol effects in both tests. The interactions were not of pharmacokinetic origin since blood and brain ethanol and dexmedetomidine levels were unaltered at the time of testing. The results suggest that ethanol effects on motor performance in mice are mediated in part via central noradrenergic mechanisms, and blockade of alpha 2-adrenoceptors by atipamezole leads to considerable antagonism of these ethanol effects.

Lowering of blood ethanol by activated carbon products in rats and dogs

Earlier studies on the effects of activated carbon (charcoal) on blood alcohol levels (BAL) in animals have been conflicting. The present study was designed to study the effects of a commercially available product (Charcoaid) and a new patented product (Alcosorb), in capsules and in suspension on the BAL of rats and dogs. We compared peak BAL and the regression of BAL with time during ethanol clearance in rats given 1.5 g/kg of carbon products in sorbitol intragastrically, followed 5 min later by 3.5 g/kg ethanol intragastrically. Peak BAL were significantly higher after Charcoaid 1 h after intubation, compared to Alcosorb and sorbitol (vehicle for the charcoal suspension). A study in which ethanol was given intraperitoneally instead of intragastrically showed no differences in ethanol BAL produced by the intragastric carbon treatments. In a crossover study using Beagle dogs, 780 mg capsules of carbon products ("low dose") given 5 min before ethanol had no significant effect on BAL. A "high" dose of 20 g of charcoal products suspended in water, followed by ethanol intragastrically, was also ineffective in lowering blood ethanol. However, carbon products suspended in a water/ethanol vehicle (20% w/v) did significantly lower peak BAL. We conclude that carbon products significantly lower BAL in rats and dogs, and that in rats, Alcosorb and sorbitol produce a greater BAL lowering effect than Charcoaid for a brief time after administration. The mechanisms of the BAL lowering effect by sorbitol and charcoal products are probably different.

Gastric emptying in the acutely inebriated patient

Fifty inebriated emergency department (ED) patients underwent evacuation of gastric contents via a nasogastric tube, in order to determine if a significant amount of ingested ethanol can be removed prior to absorption. Such a result could potentially reduce additional intoxicating effect. The gastric contents were assayed for total ethanol concentration, and a potential (postabsorption) additive blood alcohol level (PABAL) was projected and compared to the actual BAL on arrival. The type of beverage ingested and the time since last drink were recorded. BAL ranged from 108 to 637 mg/dL (mean +/- SD, 290 +/- 104.7). Gastric aspirate volume ranged from 50 to 700 mL (190 +/- 134), and contained alcohol in a range of 87 to 2271 mg/dL (475 +/- 479). Based on the distribution volume for alcohol calculated according to the patient's weight, this corresponded to a PABAL of 3 to 167 mg/dL (mean, 24.3 +/- 29.3). There was no significant correlation between the volume or concentration of gastric aspirate and the patient's stated drinking history. The authors conclude that a significant amount of ingested alcohol may occasionally be removed from absorption by the routine evacuation of gastric contents in intoxicated patients. These patients cannot be identified upon presentation, however, and these data cannot support routine use of gastric emptying in the detoxification of inebriated patients.

Effect of sucrose consumption on alcohol-induced impairment in male social drinkers

Two studies were conducted to examine the interaction between sucrose and ethanol in normal young fasting adult males. The first experiment employed a 3 (100 g sugar, 35 g sugar, 0 g sugar) x 3 (alcohol, placebo and sober) factorial design, which was carried out double-blind using aspartame to ensure that all the drinks were equally sweet. Subjects were tested for mood, memory, subjective intoxication and psychomotor performance at baseline and at times up to 3.5 h after ingestion of the drinks. An alcohol by sugar interaction was seen at 0.5 after drinking. Sugar attenuated alcohol intoxication at this time without influencing blood alcohol levels. Contrary to previous reports, the combination of alcohol and sugar failed to produce significant hypoglycemia, or any of the adverse behavioral effects associated with hypoglycemia, at later times after drink ingestion. The second experiment involved a simpler design, carried out single-blind in which the subjects receiving no sugar did not get aspartame. This was to rule out the possibility that aspartame was exacerbating alcohol intoxication instead of sugar attenuating it. The second experiment also showed that sugar can attenuate alcohol intoxication in fasting humans without altering blood alcohol levels significantly.

Alcohol and drug interactions

Interactions of ethyl alcohol with various drugs are common. Their consequences vary depending on the effects of the drugs concerned, the doses of drugs and alcohol given and their mode of administration. Pharmacokinetic interactions refer to altered tissue concentrations of alcohol or drugs or both and their metabolites which sometimes lead to serious toxic reactions. The kinetic interactions take place in the absorption or metabolism of alcohol or the drug, whereas significant interactions in their distribution phase are rare. Pharmacodynamic interactions refer to the combined actions, even serious ones, which primarily take place at the tissue (receptor?) level, with or without an important pharmacokinetic component of interaction. Acute substantial doses of alcohol given quickly tend to inhibit microsomal drug metabolism and thus enhance the effects of drugs. Chronic administration of alcohol usually induces the synthesis of cytochrome P-450 isoenzyme P-450 II E1, thus accelerating the metabolism of its own and, depending on the circumstances, of various drugs as well. Reduced actions of the agents may then ensue. If the (toxic) effect of a drug (e.g., paracetamol) depends on the formation of active metabolites acute intake of alcohol may, paradoxically, reduce the drug effect, while chronic alcohol intake enhances it. Induction of hepatic enzymes by alcohol may affect the turnover of endogenous vitamins and hormones, or even produce carcinogenic substances.(ABSTRACT TRUNCATED AT 250 WORDS)

Gastric contents alter blood alcohol levels and clearance after parenteral ethanol

Several different substances, including water, charcoal, fructose, montmorillonite clay, and liquid diets used for chronic ethanol exposure, were given intragastrically to rats, followed by a low dose of ethanol injected subcutaneously. Peak blood alcohol levels (BAL) and ethanol clearance rates were found to differ depending upon the type of gastric contents. As expected, fructose lowered peak BAL and increased ethanol clearance, and charcoal lowered peak BAL, but decreased ethanol clearance. Two liquid diets, Shorey and Sustacal, when compared to an intragastric water load, also lowered peak BAL and increased ethanol clearance of subcutaneously-administered ethanol. The difference between intragastric water and Shorey liquid diet was also seen when ethanol was administered intravenously, suggesting that absorption of ethanol from the subcutaneous site was not being affected. When sleep-inducing doses of ethanol were given subcutaneously, intragastric substances did not produce differences in sleeptimes. In in vitro studies, only charcoal was able to bind ethanol, presumably by absorption onto charcoal particles. Volume of distribution measurements were inversely related to the peak BALs measured at 60 minutes after injection, suggesting that ethanol was partitioning between the blood and stomach contents. We conclude that the presence in the stomach of various substances can lower peak BAL and increase ethanol clearance in a rapid fashion, primarily through a change in volume of distribution and possibly through a rapid change in stomach or liver metabolism of ethanol.

Effects of caffeine on social behavior, exploration and locomotor activity: interactions with ethanol

The effects of caffeine and its interaction with ethanol were examined in a test of social behavior and a holeboard test of exploration and locomotion. Male mice were injected i.p. with 15, 30 or 60 mg/kg caffeine alone or in combination with 2 g/kg ethanol. The animals were then put in pairs into a familiar arena, or examined individually in the holeboard. Only the highest dose of caffeine (60 mg/kg) had a significant effect on the time spent in social interaction and motor activity in the social behavior test: both measures were reduced. The duration and frequency of avoidance-irritability behavior was dose-dependently increased by caffeine. In the holeboard, caffeine caused a dose-dependent increase in locomotor activity. 30 mg/kg caffeine reversed the ethanol-induced reduction of time spent in social interaction, and 60 mg/kg caffeine antagonized the ethanol-induced increase in locomotor activity in both the social behavior and holeboard tests. Caffeine's effects on ethanol-induced behavioral changes are compared with those of other drugs.

Acute ethanol poisoning and the ethanol withdrawal syndrome

Ethanol, a highly lipid-soluble compound, appears to exert its effects through interactions with the cell membrane. Cell membrane alterations indirectly affect the functioning of membrane-associated proteins, which function as channels, carriers, enzymes and receptors. For example, studies suggest that ethanol exerts an effect upon the gamma-aminobutyric acid (GABA)-benzodiazepine-chloride ionophore receptor complex, thereby accounting for the biochemical and clinical similarities between ethanol, benzodiazepines and barbiturates. The patient with acute ethanol poisoning may present with symptoms ranging from slurred speech, ataxia and incoordination to coma, potentially resulting in respiratory depression and death. At blood alcohol concentrations of greater than 250 mg% (250 mg% = 250 mg/dl = 2.5 g/L = 0.250%), the patient is usually at risk of coma. Children and alcohol-naive adults may experience severe toxicity at blood alcohol concentrations less than 100 mg%, whereas alcoholics may demonstrate significant impairment only at concentrations greater than 300 mg%. Upon presentation of a patient suspected of acute ethanol poisoning, cardiovascular and respiratory stabilisation should be assured. Thiamine (vitamin B1) and then dextrose should be administered, and the blood alcohol concentration measured. Subsequent to stabilisation, alternative aetiologies for the signs and symptoms observed should be considered. There are presently no agents available for clinical use that will reverse the acute effects of ethanol. Treatment consists of supportive care and close observation until the blood alcohol concentration decreases to a non-toxic level. In the non-dependent adult, ethanol is metabolised at the rate of approximately 15 mg%/hour. Haemodialysis may be considered in cases of a severely ill child or comatose adult. Follow-up may include referral for counselling for alcohol abuse, suicide attempts, or parental neglect (in children). The ethanol withdrawal syndrome may be observed in the ethanol-dependent patient within 8 hours of the last drink, with blood alcohol concentrations in excess of 200 mg%. Symptoms consist of tremor, nausea and vomiting, increased blood pressure and heart rate, paroxysmal sweats, depression, and anxiety. Alterations in the GABA-benzodiazepine-chloride receptor complex, noradrenergic overactivity, and hypothalamic-pituitary-adrenal axis stimulation are suggested explanations for withdrawal symptomatology.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of intravenously-administered putative and potential antagonists of ethanol on sleep time in ethanol-narcotized mice

Groups of male CD-1 mice (n = 12/group) were injected intraperitoneally (IP) with 5 g ethanol/kg of body weight. After loss of righting reflex, they were given vehicle or one of 2-3 doses of reputed or potential antagonists of ethanol intravenously (IV). Sleep time was measured from loss to return of righting reflex. Mean sleep time (MST) was increased significantly (P less than 0.05) by a large dose of dl-amphetamine (24 mg/kg) and by 4-aminopyridine (1, 5 mg/kg). Significant (P less than 0.01) increases were also produced by small and large doses of aminophylline (25, 100 mg/kg) and by yohimbine (1, 5 mg/kg). MST was not altered significantly by small and medium doses of dl-amphetamine (6, 12 mg/kg), a medium dose of aminophylline (50 mg/kg), or by any doses of naloxone, thyrotropin-releasing hormone, propranolol, physostigmine, doxapram, or Ro 15-4513. When Ro 15-4513 was given IP 15 minutes before ethanol (n = 6/group), onset and duration of narcosis were not altered. None of the compounds tested was an effective IV antidote for deep ethanol narcosis because of drug side effects, toxicity, prolongation of MST, or insufficient shortening of MST.

The effect of the imidazodiazepine Ro 15-4513 on the anticonvulsant effects of diazepam, sodium pentobarbital and ethanol

The ability of the imidazodiazepine Ro 15-4513 to antagonize the anticonvulsant effects of diazepam, sodium pentobarbital and ethanol was investigated. Ro 15-4513 alone significantly lowered seizure threshold to bicuculline and this effect subtracted from the anticonvulsant effects of sodium pentobarbital and ethanol. In contrast, Ro 15-4513 completely reversed the anticonvulsant effects of diazepam, consistent with suggestions that it is a competitive ligand for benzodiazepine receptors.

Effects of beta-phenylethylamine on locomotor activity, body temperature and ethanol blood concentrations during acute ethanol intoxication

Beta-phenylethylamine (PEA) is an endogenous amine which is metabolised by MAO B. The function of this enzyme is known to be modified by ethanol so we have studied the interactions of PEA with ethanol. Rectal temperatures of rats were determined and animals pretreated with ethanol (2.5 g kg-1 IP) 90 min before PEA 20, 40, 100 mg kg-1 IP). Spontaneous locomotor activity (SLA) was then recorded, for 30 min, temperatures redetermined and blood ethanol levels evaluated. PEA increased SLA but did not alter rectal temperatures, and at 40 mg kg-1 it not only attenuated ethanol hypothermia and blood levels but also modified ethanol hypomotility. The highest dose of PEA (100 mg kg-1) decreased blood ethanol concentration and sedation but did not counteract the hypothermia. Thus PEA increased ethanol clearance, though the underlying mechanism is not totally clear. This finding is discussed in relation to its catecholaminergic and enzyme inducing characteristics.

Differential CNS sensitivity to PIA and theophylline in long-sleep and short-sleep mice

Long sleep (LS) and short sleep (SS) mice have a differential sensitivity to the behavioral actions of an adenosine agonist, R-phenylisopropyl-adenosine (PIA) that parallels their differential sensitivity to the soporific effects of ethanol. In addition to being more sensitive to the sedative effects of PIA, LS mice also show a greater excitatory response to an adenosine antagonist, theophylline (1,3-dimethylxanthine). The brain concentrations of both PIA and theophylline following drug administration do not differ in LS and SS mice, suggesting that the central nervous system of the LS mouse is more sensitive to both adenosine receptor agonists and antagonists. However, LS and SS mice made tolerant to ethanol did not show cross-tolerance to PIA. These results suggest that genetic selection for ethanol sensitivity has resulted in a parallel CNS sensitivity to purinergic drugs, but that acute alterations in sensitivity due to the development of ethanol tolerance do not involve changes in purinergic systems.

Failure of amantadine and bromocriptine to counteract alcoholic inebriation in man

Oral amantadine 100 mg and bromocriptine 2.5 + 2.5 mg, alone and in combination with ethanol (1 g/kg), were investigated in two placebo-controlled, double-blind and cross-over trials. In the first trial the psychomotor effects of amantadine and bromocriptine were compared to those of placebo, and in the second trial ethanol was added to the treatment. Bromocriptine lowered serum prolactin levels, thus confirming its absorption. Amantadine and bromocriptine alone had no psychomotor effects but unpleasant sensations, nausea and dizziness were reported after bromocriptine. Ethanol impaired performance in terms of impaired coordinative and reactive skills, lowered tapping speed, prolonged critical flicker interval and reduced gaze nystagmus angle (P less than 0.05 to 0.001; two-way ANOVA). Subjectively, ethanol induced mental slowness, clumsiness and impairment of performance (P less than 0.05 to 0.001). Amantadine and bromocriptine failed to counteract any of these ethanol-induced changes. It is concluded that in man, an acute dopaminergic activation by amantadine or bromocriptine does not significantly modify the psychomotor effects of ethanol.

Behavioral sensitivity to purinergic drugs parallels ethanol sensitivity in selectively bred mice

Behavioral responses to an adenosine receptor agonist and antagonist were examined in mice genetically selected for differential sensitivity to the soporific effects of ethanol. Both ethanol and the adenosine receptor agonist L-phenylisopropyladenosine had greater sedative and hypothermic effects in ethanol-sensitive "long-sleep" mice than in ethanol-insensitive "short-sleep" mice. Long-sleep mice were also more sensitive to the excitatory behavioral effects of theophylline, an adenosine receptor antagonist. These data suggest that adenosine may be an endogenous mediator of responses to ethanol.

Naloxone-ethanol interaction in experimental and clinical situations

The effect of naloxone on ethanol-induced impairment of psychomotor performance was studied in a series of three placebo-controlled, double-blind trials. In all trials, two successive intravenous injections of naloxone (0.4 and 2.0 mg) were given at an interval of 0.5-1.5 hours. Cross-over trials with healthy volunteers (n = 17) were performed in laboratory. In these conditions, naloxone alone had no effect on performance. Ethanol alone (1.0 and 1.5 g/kg) dose-dependently induced nystagmus and impaired coordination, reactions, hand cooperation, body balance, flicker discrimination and extraocular muscle balance. When naloxone was given after ethanol, the first injection reduced slightly but significantly ethanol-induced (1.5 g/kg) nystagmus, while the second injection did not enhance this counteraction any more. Other alcohol effects were not significantly antagonized by naloxone. The clinical part of the study, consisting of parallel groups of either naloxone (n = 11) or saline (n = 7) -treated alcohol-intoxicated (mean blood alcohol concentration 2.9 mg/ml) out-patients, most of them alcoholics, showed that no counteraction of alcohol inebriation (measured by clinical inebriation tests) was associated with the treatment with naloxone in the clinical situation either. Our results suggest that naloxone has no clinical significance in antagonizing ethanol intoxication. The inebriating effects of ethanol are not importantly mediated via central opioid mechanisms.

Zimelidine effects on memory impairments produced by ethanol

Zimelidine, a relatively specific 5-hydroxytryptamine reuptake blocker, attenuates the impairing effects of ethanol on learning and memory. The findings provide a potential basis for treatment of ethanol-related disorders and also points to the role of the serotonin system in mediating aspects of information processing in man.

Effects of serotonin on memory impairments produced by ethanol

Subjects treated with low or high doses of ethanol demonstrated impaired memory, particularly in tests involving the recall of poorly learned information. Zimelidine, an inhibitor of serotonin reuptake, reversed this ethanol-induced impairment. The serotonin neurotransmitter system may mediate learning and memory in humans and may determine some of the effects of alcohol on higher mental functions.