Chemistry of a Hangover — Alcohol and its Consequences
- DOI: 10.1002/chemv.201000074
- Author: Klaus Roth
- Published Date: 03 Maio 2011
- Source / Publisher: Chemie in unserer Zeit/Wiley-VCH
- Copyright: Wiley-VCH Verlag GmbH & Co. KGaA
How can a tiny molecule like ethanol be at the root of so much human misery?
Here we propose to get to the bottom of the chemical consequences of a night of celebrating to excess.
Many of us know from painful experience how the over-enjoyment of alcohol can disagree with our systems. Nevertheless, the tendency persists, over and over again, to suppress this simple bit of wisdom. The typical symptoms: after a short period of lifted inhibitions, accompanied by increasingly childish tomfoolery, usually serious problems with speech follow. Continuing to imbibe further leads to confusion and loss of orientation, as well as an inability to move the extremities in a coordinated fashion. The state of complete inebriation produces total helplessness from a fully impaired sense of equilibrium.
It‘s true that all the alcohol consumed will be completely metabolized within 8–12 hours, but the physical effects last longer. There arises what is colloquially referred to as a “hangover”, or “veisalgia” in medical terminology. The latter is in turn a word derived from the Norwegian “kveis”, for indisposition brought on by intemperance, and the Greek “algia” for pain. Typical symptoms include nausea, vomiting, equilibrium problems, general weakness, lack of appetite, dry mouth, etc.
Given that the ethanol culprit has already been metabolized by the time the first symptoms of a hangover appear, the question naturally arises: What is it that actually tortures us to the point that we may well feel closer to death than to life? Let’s look for chemical traces by tracking the course of an ethanol molecule from the first swig to the bitter end.
1. From the First Gulp to Inebriation
A bacchanalian evening begins with the pleasurable part. Moderate indulgence in alcohol permits a lax joviality to arise, perceived as an expression of zest for life. Everyday cares are forgotten for the moment. Most people, when a bit drunk, are also sure that they possess enhanced physical and mental abilities. But it’s all a delusion! Objective measurements show precisely the opposite: ethanol is not a stimulant, but acts instead as a sedative. The seeming euphoriant powers of ethanol are a function exclusively of its disinhibiting effect. In other words, upon becoming a bit drunk we think ourselves capable of things we would never dream of undertaking when sober.
Blood-alcohol Concentrations Between 0.3 to 5.0 ‰
Further intake of alcohol dulls the higher nerve centers, resulting in serious disturbance of musculature coordination, and the progressive decline in inhibitions may lead to miscalculations and overestimations, sometimes with dramatic consequences. For example, the risk to an automobile driver of experiencing an accident increases 25-fold when the blood-alcohol level reaches 1.5 ‰! Above 2.5 ‰, with breathing still intact, a deep state of unconsciousness may develop, but above 4 ‰ there is a real risk of respiratory arrest, and levels in excess of 5 ‰ are typically fatal.
Slow excessive drinking results in a coma; at some point the tippler simply keels over. Actually, he or she is lucky in this case, since it prevents consumption of the relatively small additional amounts of alcohol that would result in respiratory failure. Even so, mortal danger remains, since most alcohol deaths are a result of suffocation from one’s own vomit. A person who has passed out from alcohol should, therefore, always be placed in a lateral, recumbent position.
The numerical values quoted above would rise in the case of an alcoholic, due to the development of increased tolerance by the central nervous system. In fact, in 2001 there was a case recorded in Karlsruhe, Germany, of a 35-year old man being admitted to the municipal clinic with a measured blood-alcohol level of 5.8 ‰ — and he survived, thanks solely to the wonders of modern intensive-care medicine.
2. Gradual Sobering-Up
A maximal blood-alcohol concentration can be obtained with the Widmark Formula: c = A / (r • W), where c is the blood-alcohol concentration in ‰, A is the amount of alcohol consumed in g, W is the weight of the person in question in kg, and r is the distribution factor in the body, with r = 0.7 for men and 0.6 for women. This distribution factor reflects the differing water content in the bodies of men and women.
After reaching a maximum, the value for both sexes decreases linearly by 0.1 to 0.2 ‰ per hour. The cause of this linear behavior is the special kinetics associated with the enzyme-catalyzed decomposition reaction. The fundamental kinetic basis (the Michaelis-Menten equation) is dealt with in every biochemistry textbook.
► Read more on chemistry of a hangover in part 2
- M. Wallner et al., Proc. Natl. Acad. Sci. USA 2006, 103, 8540. DOI: 10.1073/pnas.0600194103
- H. J. Hanchar et al., Proc. Natl. Acad. Sci. USA 2006, 103, 8546. DOI: 10.1073/pnas.0509903103
Prof. Klaus Roth
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