Some pharmacological actions of alcohol.

The contribution which alcohol may make to a man's nutrition varies considerably. Alcohol is not an essential dietary constituent, but it is commonly consumed, and unlike most foods it has notable subjective and objective effects in quantities which contribute trivially to the total daily calories. Moderate drinkers are much commoner than those who consume to excess, and it will therefore be most interesting and most relevant to consider the effects of small doses of alcohol on healthy subjects. When alcohol is taken by mouth, it is absorbed rapidly from the stomach, especially if the stomach is empty, and it enters the blood stream and thence is widely distributed in the body. Some 95998% is removed by oxidation in the liver and eisewhere, and the rest is excreted unchanged in the urine and by exhalation. As a rough approximation the rate of removal, by one channel or another, is about 10 ml./h in a healthy adult and is less dependent on the concentration in the body fluids than might be expected. (See Jacobsen (1952) for review.) The concentration of alcohol in the blood during or after drinking therefore depends particularly on the dose, on the duration of consumption, and on whether the stomach is empty or full; a given dose of alcohol will produce only about half the peak concentration of alcohol if it is taken on a full stomach instead of an empty one (Mellanby, 1919). Individuals vary in their metabolism of alcohol as well as in their response to a given amount, and on the whole habitual drinkers of large amounts metabolize alcohol a little faster than more moderate drinkers; but with these factors in mind it is roughly possible to predict fairly reliably the course of the blood-alcohol concentration curve after a drink or drinks. Conversely, from a knowledge of the concentration of alcohol in the blood or urine, it is possible to predict with reasonable certainty the minimum amount of alcohol the subject must have consumed to attain such a level-a point of some forensic importance. One of the earliest effects of consuming alcohol is the recognition of its characteristic taste and smell, or that of the liquid which contains it: and with stronger drinks this is followed by mild epigastric sensations when the material reaches the stomach. These effects are important experimentally, because it is very difficult to produce a dummy alcoholic drink which is pleasant to consume but contains no ethanol. The point is important because it makes distinction almost impossible between the effects of ethanolper se and the effects of drinking, with all the emotional and cognitive associations involved. The difference does not matter much in considering the practical consequences of drinking, but it considerably complicates the psychological and pharmacological problems in unravelling exactly how alcohol acts on the brain. Many attempts have been made to provide proper dummy