This section is from the book "Materia Medica: Pharmacology: Therapeutics Prescription Writing For Students and Practitioners", by Walter A. Bastedo. Also available from Amazon: Materia Medica: Pharmacology: Therapeutics: Prescription Writing for Students and Practitioners.
As it cannot evaporate from the stomach, alcohol dilates the vessels and gives a feeling of warmth in the stomach. Below a strength of 10 per cent. it has practically no other effect unless taken in too large quantities to be absorbed rapidly. But in strength above 50 per cent., and, to many stomachs, in much weaker dilution, it is powerfully irritant and capable of causing inflammatory changes. Its local irritant properties depend on its percentage dilution rather than on the actual amount of alcohol.
The chief functions are absorption, motility, and secretion.
Ordinary amounts of alcohol in any dilution are quickly absorbed, and will usually have disappeared from the stomach in less than half an hour (Cushny says 20 per cent. absorbed by stomach and 80 per cent. from intestine.) But during a meal an amount of alcohol can be ingested without systemic effects that, if taken before the meal, i. e., on an empty stomach, would produce distinct feelings or manifestations of intoxication. This is a fact that is well known to the laity, and the difference is due to admixture with the food and the consequent retardation of absorption. The effect of alcohol on the absorption of other substances, such as digestive products, water, and drugs, is usually favorable, unless the alcohol is present in strength great enough to injure the cells of the mucous membrane or to produce a coating of thick mucus, or to act as an astringent, i. e., in a strength above about 20 per cent.
Kast's experiments with alcohol up to 20 per cent. strength indicated increased motility; those of Gluzinski show retarded motility. From an experimental point of view, therefore, the effect on motility remains undecided. Yet, clinically, alcohol seems to increase the motor functions, for solutions containing above 20 per cent. and the distilled liquors, even when diluted to 20 per cent., are prompt and powerful carminatives.
In the stomach, also, 50 per cent. alcohol, as in a distilled liquor, quickly results in the secretion of a protecting coat of thick, tenacious mucus. This not only protects the mucous membrane from further injury by the alcohol, but by retarding absorption serves to protect the liver and to lessen the systemic effects.
We are able to divide the action of alcohol and alcoholic drinks upon this secretion into three distinct periods, viz.:
1. The period of excitation of the taste-buds or olfactory nerves to produce appetite.
2. The period during which the alcohol is in the stomach.
Pawlow's work established the fact that appetite is of great importance in the production of the first gastric juice, the so-called "appetite juice," or "psychic gastric juice." In experiments with dogs he noticed that a number of substances, for example, white of egg, will remain absolutely-undigested if placed in the stomach without the knowledge of the animal; but that if then his appetite is stimulated, as by the sight or smell of food, the white of egg is soon digested because of the appearance of gastric juice. Hence alcoholic drinks which promote the appetite, whether palatable wines or bitter malt liquors, have a distinct influence in the production of the psychic secretion or appetite gastric juice, and so may favor digestion.
Knowledge of the effect upon the secretion while the alcohol is in the stomach was obtained from experiments on Pawlow dogs and dogs with gastric fistulae, and in addition from a few observations made upon patients with gastric fistulae, A number of studies were made by Kast upon a girl who had had a portion of the esophagus removed and a gastric fistula established. The work of Chittenden and Mendel was done on dogs with gastric fistulae, a regular meal being allowed by mouth, and measured quantities of alcohol being put in through the fistula. From these observations we learn that the direct influence of alcoholic solutions up to about 10 per cent. in strength is practically none at all upon either the rate or the character of the gastric secretion; while from amounts above about 20 per cent. secretion is distinctly retarded. Between these strengths there is a variable influence. There is some retardation of secretion from the malt beverages because of their large amount of extractive matters, and from the red wines because of their tannic acid; but the retardation in these cases is not due to the alcohol.
When alcohol is injected into the blood of a dog, a flow of gastric juice results, and in some of the cases at least some of the alcohol is excreted into the stomach. If alcohol is placed in the rectum or in any part of the intestine, absorption is also followed by a flow of gastric juice. And when alcohol is placed in the stomach itself, a copious flow of gastric juice, perhaps two or three times that in control dogs, takes place after all the alcohol has disappeared from the stomach and passed into the blood. In all these cases the gastric juice contains hydrochloric acid out of all proportion to the amount of pepsin present. Radzkowski has shown that the pepsin of this juice is merely that already transformed from the pepsinogen in the glands, and that no new pepsin is formed as the result of the absorbed alcohol, that is to say, only the chief cells of the stomach are stimulated.
The secretion following administration by rectum or into the blood is much less in amount than that following stomach doses, but has the same composition. The secretion after absorption lasts until practically all the food has passed the pylorus, and it is probable that alcohol either stimulates the acid-secreting cells directly, or else causes the formation of a hormone, which is absorbed into the blood and stimulates the cells. The effects would seem to be of the same nature as those from the hormone known as gastric secretin. This increase in the secretion of acid and in the amount of gastric juice after the absorption of the alcohol is of practical importance. For when rectal feeding in an irritant stomach condition, such as ulcer, is adopted for the purpose of saving the stomach from irritation, it is advisable to omit alcohol from the enema. In old alcoholics the stomach is usually the site of a chronic inflammation.