Abstract The effect of naloxone, picamilon, aminostigmin and metadoxil on the caurse and outcome of experimental severe (0,5ED50) and extremely severe (1,0ED50) ethanol intoxication, as well as metadoxil effectiveness in patients with acute alcohol intoxication has been studied. It has been established that picamilon slightly accelerated the animal transition from a lateral position under priming with the dose of 0,5ED50, while under priming with the dose of 1,0ED50 it aggravated intoxication outcome. The use of naloxone resulted in the development of secondary coma in some cases and animal death following the apparently uneventful period. Aminostigmin was demonstrated to possess a pronounced awakening effect, but its use in limited by a nerrow range of active and toxic doses. The most effective agent proved to be metadoxil, that had marked awakening and therapeutic action in experiment and while showing no rebound effect, resulted in the improvement in the course and outcome of intoxication in hospital setting. Judging by the results of the experimental study of poison toxicokinetics, it can be suppoused that the awakening effect of metadoxil (in the doses, used) is not associated with ethanol concentration decrease in bioenvironment, but the use of this agent in the hospital setting, however, resulted in the reduction of blood ethanol level.

Key words:
ethanol, acute intoxication, treatment, naloxone, picamilon, aminostigmin, metadoxil.

INTRODUCTION The dynamics of acute alcohol and its substitude intoxication cases in the 90-s of the last century and at the beginning of this century has been analyzed based on case history data in the St.-Petersburg Interregional Center for Intoxication Treatment, Emergency Treatment Research Institute after I.I. Janelidze. The analysis showed that there were two peaks of intoxication incidence: the first occurred at the beginning of the 90-s with the maximum being in 1994, the second was in 1999 - 2001. In 2002 there have been registered 860 cases of alcohol and its substitutes intoxication, which is 2 times less that in 2001 and the lowest rate for the last 12 years. However, these data included 15% of all acute intoxications. In other regions of the country there have been no substantial reduction in the rate of alcohol and its substitutes intoxication reported in 2002 [1]. The most alarming in the fact that patients with this diagnosis being admitted to the hospital appear to be much younger that before, the number of female patients has also increased.

Acute alcohol intoxication is known to be characterized by encephalopathy of mixed (toxic and hypoxic) origin, manifested by coma and neurologic disturbances, aspiration-obturation type of respiratory disorders, and in advanced cases - by central type of respiratory disorders, acute cardiovascular insufficiency, metabolic acidosis and parenhimatous organ involvment, first of all - the liver [2].

The therapy of acute alcohol intoxication consists of a number of measures directed to the cessation of further adsorption and accelerated poison elemination, as well as measures to support vital functions and steady internal body medium complications prevention and therapy. However, while these is constant improvement of therapeutic techniques, one cannot consider this problem to be solved, since the lethality in this group of patients ranges from 2,0 to 7,8 % according to literature data, and is as high as 40 % in the most sever cases [2].

At present there are two main perspective tendencies in the improvement of acute alcohol intoxication treatment: the first - the use of agents acting on the brain mediator systems; the second - the use of substances, accelerating metabolism and ethanol and its biotransformation products clearance, also normalizing interstitional metabolism.

Among "mediator" type agents so-called "pure" antagonists of opiate receptors attract the clinicians attention [3,4]; there have lately been some reports of successful alcohol intoxication treatment with agents of cholinomimetic and GABA-ergic action [5].

As to the substances, which are potentially able to accelerate alcohol metabolism in the body, the list of them is rather limited. The most widely used agent is sodium hypochloride (0,06 % solution), which to the opinion of many authors, can oxidate ethanol and its metabolites in vivo [6,7,8]. Other oxidating agents, such as sodium metabisulphite, hydrogen peroxide, potassium permanganate for some reasons have not found a wide use in practice. The most perspective agent in this group, metadoxil, has been used in alcoholic withdrawal syndrome treatment and recommended by some authors as a therapeutic measure fore acute alcohol intoxication [9,10]. It should be noted, that we could not find in the literature available the works on experimental background to use of agents of both mediator and metabolic action.

The goal of the study of the effect of mediator and metabolic agents on the course, outcome and ethanol toxicokinetics in acute alcohol intoxication of various severity, as well as the clinical use of the most effective of them.

MATERIALS AND METHODS
This report is based on the data obtained as a result of experimental study and clinical experience. Fore the experimental part of the investigation the following agents have been chosen: naloxone - "pure" opiate antagonist, devoid of morphine - like action, aminostigmin - reversible cholinesterase inhibitor of mainly central action, picamilon - GABA-ergic agent of nootrop group; metadoxil - metabolic therapeutic agent.

Experimental models were white male rats weighing from 140 to 180 g, ethanol was intraabdominally injected as a 33 % solution in a single dose 0,5 and 1,0ED50 to produce an ethanol intoxication pattern of severe and extremely severe degree respectively.

Laboratory animal were subdivided into 5 groups: the first - a control group; the second - animal were injected aminostigmin (0,1 mg/kg), the third - metadoxil (100 mg/kg), the fourth - naloxone (0,05 mg/kg), the fifth - picamilon (300 mg/kg). The agents were intramuscularly injected in a single dose 30 minutes after the priming. The control animals were administered the corresponding amounts of saline solution.

Survival, the time of lethal outcome, the time of animal transfer from a lateral position, concentration levels in blood of ethanol and its metabolites (acetaldehyde, acetic acid) and acetone have been estimated.

The study data are based on the results of examination of 106 patients aged 17 - 63 years (71 males, 35 - females), treated in the St.-Petersburg Interregional Center for Intoxication Treatment, Emergency Treatment Research Institute after I.I. Janelidze for acute ethanol intoxication of severe and extremely severe degree. Patients suffering from craniocerebral injury and severe somatic pathological conditions were excluded from the study.

All patients were initially admitted to the intensive care unit because of vital functions disorders: consciousness depression (third degree coma), external respiration disturbances (all patients underwent respiratory ventilation), acute cardiovascular insufficiency events. On admission the patients were divided into two groups: the first - (40 patients) received standard therapy, the second (66 patients) were administered metadoxil (intravenously in droplets, in dose 600 mg with the rate 13,3 mg/min during 45 min). The patients of the above groups did not significantly differ by sex, age, severity of the condition, volume and timing of prehospital therapeutic treatment.

The duration of coma and respiratory ventilation, the period of stay in an intensive care unit, lethality, clinical and laboratory findings, toxicokinetic data of ethanol and its metabolites in blood have been estimated.

The concentration levels of ethanol and its metabolites (acetaldehyde, acetic acid) and acetone in blood were determined by means of gas chromatography using paraphase analysis technique.

Statistical data processing was conducted by T - Student criterion.

THE RESULTS AND DISCUSSION
It has been found that in case of priming laboratory animals with ethanol in the dose 0,5ED50, all agents used in certain doses, exerted influence on intoxication course. First of all, it concerns the decrease in the period of the animals stay in a lateral position, which indicated the awakening effect of the agent, the degree of the effect varying. The administration of picamilon resulted in slight decrease in the period of animals stay in a lateral position (Т > 0,05). Aminostigmin possessed more pronounced awakening effect, which decreased this rate 1,8 times as compared with the control group (Т < 0,05). In their turn, two other agents - metadoxil and naloxone demonstrated effectiveness surpassing that of aminostigmin, decreasing the period of stay in lateral position 2,5 - 3,0 times (up to 1,8 +/- 0,8 and 1,5 +/- 1,0 hours respectively; in the control group - 4,7 +/- 1,2 hours; Т < 0,01).

When simulating alcohol intoxication of extremely severe degree, somewhat different results have been obtained. Lethality rate estimation demonstrated that only picamilon administration was accompanied by the increase of animal deaths (Tab.1). In other groups this rate was much lower than that of the control group Thus, when administering aminostigmin and naloxone lethality rate was 10 % and 20 % respectively, and in the group receiving metadoxil, there were no any lethal outcomes registered.

Table 1
Dynamics of activity and lethality rates when priming animals with ethanol in the dose of 1,0ED50 under the condition of agents administration (M +/- m).

Rates	Control	Agents
		Picamilon (n=20)	Metadoxil (n=20)	Aminostigmin (n=20)	Naloxone (n=20)
Lethality in group (%)	60	70	0*	10*	20*
Mean time of death (hours)	3,1 +/- 0,5	3,9 +/- 0,7	0*	4,5 +/- 0,6	6,1 +/- 0,7*
Time of animal transfer from a lateral position (hours)	8,2 +/- 0,9	7,3 +/- 0,8	3,2 +/- 0,4*	4,7 +/- 0,6*	3,7 +/- 0,7*

* - compared to the control group, reliable (Т < 0,05)

It should be emphasized, that mean time of animal deaths was the greatest in the group receiving naloxon. However, in case of naloxone administration, the initial period of a pronounced awakening effect was followed by sharp animal activity decrease, with the relapse into coma in 70 % of cases, 25 % of which resulting in unfavorable outcome. In other groups, animal death was seen in the period of maximum toxic effect of ethanol, that is soon after priming, there was no coma recurrence.

In the group receiving metadoxil, rapid restoration of activity was noticed, that was not accompanied by rebound effect. Aminostigmin being administered also decreased the time of animals stay in a lateral position, exhibiting much lower effectiveness compared with metadoxil and naloxone. It should be noted, that aminostigmin doses approached toxic ones, and their exceeding the level of 0,1 mg/kg resulted in the development of marked tremor and convulsions when animals changed their position from a lateral one.

In order to determine the mechanisms of agents actione we have studied their effect on the toxicokinetics of ethanol and its metabolites. Blood concentration levels of ethanol, acetaldehyde, acetic acid and acetone were measured 6 hours after priming, that corresponded to the time of animal transferring from a lateral position.

It has been established that blood ethanol concentration was the highest in animals receiving picamilon (Tab.2). Metadoxil and aminostigmin administration was not accompanied by reliable change in above rate. The lowest blood ethanol concentration was recorded in the group receiving naloxone. However, all the reported ethanol concentration changes can not be assumed to be reliable compared with the control groups.

As to acetaldehyde concentration, it proved to be the lowest in the groups receiving naloxone and metadoxil, the rate being reliably lower than in the control group (p < 0,05). When administering aminostigmin and picamilon, the acetaldehyde concentration level was slightly higher than that of the control group, but these are not reliable.

Table 2
Alcohol toxicokinetics rates under the animal priming in the dose of 1,0ED₅₀ (M +/-m)

Groups	Blood concentration rates
	Ethanol (g/l) (n = 5)	Acetaldehyde (mg/l) (n = 5)	Acetone (mg/l) (n = 5)
Control	2,59 +/- 0,18	0,092 +/- 0,005	0,0030 +/- 0,0005
Receiving:
Metadoxil	2,71 +/- 0,17	0,070 +/- 0,005*	0,0016 +/- 0,0002*
Picamilon	3,14 +/- 0,28	0,096 +/- 0,005	0,0028 +/- 0,0007
Naloxone	2,02 +/- 0,26	0,071 +/- 0,006*	0,0017 +/- 0,0003*
Aminostigmin	2,81 +/- 0,21	0,099 +/- 0,004	0,0033 +/- 0,0007

* - compared to the control group, reliable (Т < 0,05)

Acetic acid has been found only in animals receiving picamilon, while in the groups studied as well as in intact animal it has not been determined. While estimation blood acetone concentration levels, it has been established, that in the group of animals receiving aminostigmin its value was the highest; picamilon administration in fact exerted no any effect on this finding, but this variations would not be reliable compared with the control group. At the same time blood acetone level in animals receiving metadoxil and naloxone, was twice as lower as in the control group (p < 0,05). Summarizing the experimental data of the study, it can be said that the most effective of all agents being investigated appeared to be metadoxil. It actually decreased the time of animals stay in a lateral position (both in severe and extremely severe intoxications), prevented the development of lethal outcomes, while having no influence on the blood ethanol level, reliably decreased acetaldehyde and acetone concentration. Naloxon proved to have the same awakening effect as metadoxil, having similar action on ethanol toxicokinetics and interstitial metabolism. However, the model of extremely severe intoxication demonstrated a rebound effect of naloxone, which was manifested by repeated development of coma following the period of seemingly improved clinical state. On the basis of experimental study the most effective of all the agents - metadoxil - has been chosen for clinical study. The clinical study data analysis demonstrated (Tab.3), that metadoxil administration decreased by 1,63 times the duration of coma (from 10,3 +/- 3,2 to 6,3 +/- 2,9 hours; Т < 0,05), and by 1,84 times - the duration of respiratory ventilation (from 9,4 +/- 2,5 to 5,1 +/- 2,4 hours; Т < 0,05). Reliable decrease of the patients stay in an intensive care unit has been noted indicating rapid patient condition stabilization. Of significance is the fact, that in group of patients treated with metadoxil, the lethality rate was reliably lower, than in patients treated by standart therapeutic methods.

Table 3
Metadoxil effectiveness clinical criteria (н +/- m).

Rate	Patient`s groups
	Control(n=40)	Receiving Metadoxil (n=66)
Patients age (years)	37,2 +/- 2,0	35,6 +/- 2,3
Duration of respiratory ventilation (hours)	9,4 +/- 2,5	5,1 +/- 2,4*
Duration of coma (hours)	10,3 +/- 3,2	6,3 +/- 2,9*
Patients stay in an intensive care unit (hours)	21,2 +/- 4,2	11,5 +/- 3,6*
Number of lethal outcomes (absolute/%)	10(25,8)	4(6,1)*

* - compared to the control group, reliable (Т < 0,05)

The study of poison toxicokinetics demonstrated that given equal ethanol concentration levels in the investigated groups, only patients receiving metadoxil showed reliable reduction of blood alcohol level 6 hours following the agent administration (Tab.4). Later in this group ethanol concentration level continued to decrease much faster than in the control group, the variation between groups being reliable.

Table 4
Ethanol blood concentration level in patients with acute alcohol intoxication under the use of metadoxil.

Patient`s groups	Time for the admission (hours)
	On admissionЕ	3	6	9	12
Control	4,43 +/- 0,43	3,86 +/- 0,42	3,25 +/- 0,26	2,75 +/- 0,33	2,06 +/- 0,29
Metadoxil	4,61 +/- 0,37	3,28 +/- 0,46	2,46 +/- 0,27*	1,88 +/- 0,31*	1,09 +/- 0,34*

* - compared to the control group, reliable (Т < 0,05)

As to blood acetaldehyde concentration variations, after slight initial increase (by the 3-d hour) it gradually decreased, reaching it`s minimum by the end of the period under study. In patients receiving metadoxil, blood acetaldehyde concentration level was lower than in the control group during the whole period of study, but these variations were considered to be reliable only in the first 6 hours since the agent administration.

The results of identification of acetic acid were similar to findings obtained during the experimental study. This alcohol metabolite was not found in any of the blood samples examined.

It has been established that after initial increase (in 3 hours) blood acetone concentration level in patients of the control group gradually was decreasing, then it again increased by the 12-th hour. In the group receiving metadoxil during the whole period of observation reliable reduction of blood acetone concentration was noted.

The data obtained support the opinion about the important role of mediator system functional disorders play in the mechanism of ethanol cerebrotoxic action. The pharmacological probes used are characterised by rather high specificity, hence, it can be said that at least two mediator system - opioid and cholinergic participate in the alcoholic coma production. The tendencies of these disorders are evidenced by agent pharmacological effects - correspondinly naloxone opiate receptor antagonist and aminostigmin mediated cholinomimetics. At the same time, the genesis of secondary coma developing in naloxone treated animals remains quite unclear. It can be assumed that like the stimulations action in severe barbiturate intoxication, which also possess an awakening effect but aggravate intoxication outcomes, naloxone cases CNS functional activity in those intoxicated with ethanol, ft the same time not providing its adequate energy supply.

Picamilon (GABA and nicotinic complex) slightly reduced the duration of alcoholic coma in case of severe intoxications and increased lethality rate in case of extremely severe intoxications. The above effect is likely to be caused by GABA, being a constituent part of the agent and able to enhance the ethanol narcotic action. As to metadoxil, this agent contains pyridoxale and pirrolidone-carboxylate complex. According to some reports in the literature, besides metabolic effects can influence brain mediator systems, stimulating GABA-chlorionic complex and increasing acetylcholine and dofamine production. Its cholinomimetic effect is believed to be the most important, since this effect is similar to that of aminostigmin.

Besides the mechanisms mentioned, metadoxil is likely to influence ethanol and acetaldehyde biotransformation rate; the study of patients findings in acute alcohol intoxication support this assumption.

Thus, the results of the experimental and clinical studies make us think of metadoxil as the agent of choice among the agents being investigated for the treatment of severe and extremely severe ethanol intoxication.

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