This section is from the book "Materia Medica Pharmacy, Pharmacology And Therapeutics", by W. Hale White. Also available from Amazon: Materia Medica Pharmacy, Pharmacology And Therapeutics..
It is a powerful antiseptic, preventing the formation of and killing putrefactive bacteria. If applied to the skin, alcohol quickly evaporates. It therefore cools the skin, which consequently becomes pale from the contraction of the small vessels; owing to this less sweat is secreted. Alcohol is thus refrigerant, astringent and anhidrotic. But if evaporation is prevented in any way, such as by a watch-glass or a piece of gutta-percha, or the alcohol is rubbed in, it quickly absorbs water from the skin, and thus hardens it. Having thus passed through the epidermis, it dilates the vessels, causes a feeling of warmth, and produces a rubefacient effect. It has the power of coagulating albumin, but the coagulum quickly re-dissolves. It extracts water from all tissues.
Mouth. - When concentrated, alcohol produces a feeling of warmth, or often even a burning sensation, in the mouth. If held there for some time, the albumin of the superficial tissues is coagulated, and the mucous membrane becomes whitish, congested, and opaque; but this appearance soon disappears, as the coagulum is re-dissolved by the fluids of the tissues. Directly after the alcohol is put in the mouth there is an increased flow of saliva, and the pulse may be quickened; these results are reflex, for they occur before there is time for the alcohol to be absorbed. Alcohol has a slight local anaesthetic effect.
Here also, if the alcohol is sufficiently concentrated, there is a sensation of warmth or even of burning. If only small quantities are given, the gastric vessels dilate, the mucous membrane becomes red, and there is an increased secretion of gastric juice. All this has been seen to happen in cases of gastric fistula. The result of these effects is that the appetite is sharpened, and this explains the custom, common with many people, of taking a little alcohol immediately before meals, and also the common experience that alcohol taken during meals aids digestion. It also increases the activity of the gastric movements and promotes absorption. Thus there are several ways in which moderate doses of alcohol may help the digestive process, and Binz has actually demonstrated, by removing the gastric contents at stated times after a meal, that alcohol aids digestion, and by giving potassium iodide he showed that it increased the rapidity of absorption. In some cases it produces a local anaesthesia in the stomach, and so it may relieve gastric pain. It is to a slight extent decomposed into aldehyde and acetic acid, and consequently some of the pepsin, peptones, and proteids are precipitated. This hinders digestion, but usually not sufficiently to outdo the aid due to the vascular dilatation, the increased secretion, and the greater movement. The effect of large doses is very harmful. The activity of the gastric juice is destroyed, the gastric walls are inflamed, large quantities of mucus are poured out, and if the over-indulgence is continued chronic gastritis ensues, the gastric glands atrophy, and consequently we get the permanent dyspepsia of drunkards.
A single dose of alcohol introduced into the stomach in a concentrated form, e.g., clear brandy, immediately produces important reflex effects. The heart beats more rapidly and more forcibly, the vessels of the whole body dilate, especially those of the skin; hence there is a feeling of warmth. The blood-pressure rises. These reflex effects are well seen in the immediate restoration of a fainting person by the ingestion of a single dose of brandy. Diluted alcohol, e.g., beer, does not produce them. They are quickly followed by the effects of alcohol upon the circulation due to its presence in the blood after absorption.
Here alcohol has a slight astringent effect, and consequently it may check diarrhoea.
Alcohol is absorbed more largely by the blood-vessels than the lacteals. It first increases and then diminishes the amoeboid movements of the white blood-corpuscles. It so acts on the red corpuscles as to prevent oxyhaemoglobin from readily yielding up its oxygen, consequently it diminishes the oxidation of the tissues. This, in habitual drinkers of large quantities of alcohol, may lead to an imperfect combustion of fat, consequently it accumulates in the tissues, and obesity, which is often increased by the amount of saccharine matters alcoholic liquids contain, results. The skin acquires a velvety feeling.
Alcohol is slightly antipyretic, lowering the temperature in fever. This is chiefly due to cutaneous vascular dilatation and rapidity of circulation, but also slightly, perhaps, to general diminished oxidation. A litre, about a quart of Rhine wine of average strength produces by its oxidation about as much heat as five or six tablespoonfuls 100. to 120. c.c of olive oil. Neither the intake of oxygen nor the output of carbon dioxide is altered by alcohol, therefore as it has been oxidized in the body it saves the tissues and is a food. Repeated observations have shown the proof of this, for moderate doses of alcohol diminish the output of urea and uric acid, 6 or 7 per cent.; and that it is a food is also proved by the fact that the weight of the body may be maintained if a large amount of alcohol is taken, even if the rest of the food is very small in amount. Alcohol ceases to be a food when it is ingested in such large amounts that it cannot be completely oxidized. In this instance the excess is likely to be harmful.
If only moderate doses are drunk, very little alcohol leaves the body in the urine; with large doses the case is different.
The effects upon the circulation reflexly produced by stimulation of the mouth and stomach have already been mentioned. After alcohol is absorbed it influences the heart markedly. It beats more powerfully and more rapidly, the pulse becomes fuller; these results are due to the peripheral arterial dilatation and to a stimulating effect on the accelerator nerves. The vaso-motor system is acted upon, all the vessels of the body dilate, especially those of the skin; therefore, if he previously felt cold, the person who has taken the alcohol feels warm. The blood-pressure rises, the increased action of the heart more than compensating for the vascular dilatation. This is not true for dogs, as has been demonstrated in the laboratory (Long). The direct effects of alcohol on the circulation after absorption appear more slowly and last longer; but they are clearly similar to those due to the reflex stimulus from the stomach, and therefore they continue them. The result of the increased circulation through the various organs is that they work to greater advantage, hence the mental faculties are brightened for a time, the muscular strength seems increased, more urine is passed, and the skin perspires. The person who has taken the alcohol, in fact, usually feels generally better for it. This is by no means always so; some persons have a headache or feel very sleepy immediately after alcohol. This is probably because the vessels of the abdomen or skin have dilated so excessively that almost all the blood in the body is in them, and consequently there is very little in the brain. There are many individual peculiarities in the effects of alcohol.
It has been repeatedly proved that these good results are but transitory. The heart, although at first stimulated, is more exhausted after the stimulation has passed off than it was before. This is also true of all the organs of the body stimulated by the increased circulation induced by alcohol. In many campaigns and arctic expeditions it has been found that although at first the men, after taking alcohol, could do more work, yet soon they felt so tired and exhausted, that on the whole they could do much more without than with the alcohol. Large doses of alcohol do not stimulate the heart at all; they paralyze it, both reflexly from the stomach and after absorption. Enormous doses poured into the stomach kill almost immediately by reflex action. A drunkard who is "dead drunk" is, accurately speaking, one who is killed by the paralyzing effect of alcohol on the heart; but the phrase is often applied to any one who is very drunk.
Alcohol is a mild diaphoretic, partly because of its vaso-dilator action, and perhaps also because of some direct influence on the sweat-glands. As just mentioned, the cutaneous vascular dilatation leads to a feeling of warmth if the patient's cutaneous vessels were previously contracted from cold. It may be that part of the antipyretic power of alcohol is due to increased radiation from the dilated vessels, and also to evaporation of the increased amount of sweat. If a person is in a cold atmosphere, alcohol, by increasing the radiation from the skin, leads to the loss of so much heat that he may die from cold, although at first the increased cutaneous circulation, making him feel warmer, gives him a delusive feeling of warmth.
About 5 per cent. of the alcohol ingested - unless very large quantities are taken - is excreted unchanged, mostly in the urine, to a less extent in the expired air, only the merest trace in the sweat and none in the milk or faeces. Most of it is oxidized in the body. It acts as a diuretic; probably this is a secondary result of its vascular effects, but it probably also acts directly on the glomeruli.
Unless the dose be very large the whole nervous system is stimulated, perhaps to a slight extent directly, but chiefly as a secondary result of the vascular dilatation and cardiac stimulation. The highest functions are most affected. The person who has taken the alcohol talks more fluently and brilliantly, his wits are sharpened, he has a feeling of strength. If the dose has been large, the stage of exaltation of these or any other functions quickly passes into one of depression, the highest functions being affected first, and the stimulation and depression of function proceed regularly from the highest to the lowest. The action of alcohol thus illustrates both the fact that stimulation is usually succeeded by depression, and also the "law of dissolution," which (see p. 104) states that functions which have appeared latest in the animal series or the individual are the most easy to influence, those which have appeared earlier are less easy to influence; and so by regular sequence till we arrive at those functions which are first developed, which are the last to be influenced. The stimulation and subsequent depression of function, therefore, proceeds in a descending scale from the highest or least firmly fixed function to the lowest or most firmly fixed. Thus the power of judgment is abolished very early by alcohol; this is so while the imagination, the emotions, and the power of speech still remain stimulated; but soon the power of imagination goes, the patient loses all command over his emotions, he cries and laughs irregularly, but this soon stops. He next begins to lose control over his speech, talking incoherently and thickly; shortly afterwards he cannot talk at all, but can only make a noise. Muscular movements, which are not so highly developed as those of speech, are next affected; delicate, lately developed movements, as writing, feeding himself, etc., are for a time performed inco-ordinately, but soon they are paralyzed. Next the muscular movements, developed before these, are implicated, and the patient cannot undress himself or walk straight, and inco-ordination of these movements passes into the inability to do them at all. Next the activity of the reflex centres of the cord is abolished, the patient passes his urine and faeces involuntarily. Then the respiratory centre, which was previously stimulated, becomes paralyzed, breathing is difficult, and the face is livid. Lastly, the heart, which was also at first stimulated, is paralyzed, and the patient dies. The depression of the reflex centres of the cord accounts for the fact that injuries which would kill a sober man do not kill a drunken one, for the heart and respiration, owing to the general central depression, are not affected reflexly by them.