Blood Alcohol Content - Metabolism and Excretion

Metabolism and Excretion

Alcohol is removed from the bloodstream by a combination of metabolism, excretion, and evaporation. The relative proportion disposed of in each way varies from person to person, but typically about 95% is metabolised by the liver. The remainder of the alcohol is eliminated through excretion in breath, urine, sweat, feces, milk and saliva. Excretion into urine typically begins after about 40 minutes, whereas metabolisation commences as soon as the alcohol is absorbed, and even before alcohol levels have risen in the brain.

Alcohol is metabolised mainly by the group of six enzymes collectively called alcohol dehydrogenase. These convert the ethanol into acetaldehyde (an intermediate that is actually more toxic than ethanol). The enzyme acetaldehyde dehydrogenase then converts the acetaldehyde into non-toxic Acetic acid.

Many physiologically active materials are removed from the bloodstream (whether by metabolism or excretion) at a rate proportional to the current concentration, so that they exhibit exponential decay with a characteristic halflife (see pharmacokinetics). This is not true for alcohol, however. Typical doses of alcohol actually saturate the enzymes' capacity, so that alcohol is removed from the bloodstream at an approximately constant rate. This rate varies considerably between individuals; Another sex based difference is in the elimination of alcohol. Persons below the age of 25, women persons of certain ethnicities, and persons with liver disease may process alcohol more slowly. Many East Asians (for example, about half of Japanese) have impaired acetaldehyde dehydrogenase; this causes acetaldehyde levels to peak higher, producing more severe hangovers and other effects such as flushing and tachycardia. Conversely, members of certain ethnicities that traditionally did not use alcoholic beverages have lower levels of alcohol dehydrogenases and thus "sober up" very slowly, but reach lower aldehyde concentrations and have milder hangovers. Rate of detoxification of alcohol can also be slowed by certain drugs which interfere with the action of alcohol dehydrogenases, notably aspirin, furfural (which may be found in fusel alcohol), fumes of certain solvents, many heavy metals, and some pyrazole compounds. Also suspected of having this effect are cimetidine (Tagamet), ranitidine (Zantac), and acetaminophen (Tylenol) (paracetamol).

Currently, the only known substance that can increase the rate of metabolism of alcohol is fructose. The effect can vary significantly from person to person, but a 100g dose of fructose has been shown to increase alcohol metabolism by an average of 80%.

Alcohol absorption can be slowed by ingesting alcohol on a full stomach. Spreading the total absorption of alcohol over a greater period of time decreases the maximum alcohol level, decreasing the hangover effect. Thus, drinking on a full stomach or drinking while ingesting drugs which slow the breakdown of ethanol into acetaldehyde, will reduce the maximum blood levels of this substance, and decrease the hangover. Alcohol in non-carbonated beverages is absorbed more slowly than alcohol in carbonated drinks.

Read more about this topic:  Blood Alcohol Content

Other articles related to "metabolism, metabolism and excretion, excretion":

Standard Metabolic Rate - Medical Considerations
... A person's metabolism varies with their physical condition and activity ... Weight training can have a longer impact on metabolism than aerobic training, but there are no known mathematical formulas that can exactly predict the length and ... Menopause may also affect metabolism ...
Metabolism - History
... information History of biochemistry and history of molecular biology The term metabolism is derived from the Greek Μεταβολισμός – "Metabolismos" for "change", or "overthrow ... The history of the scientific study of metabolism spans several centuries and has moved from examining whole animals in early studies, to examining individual metabolic reactions in modern biochemistry ... The first controlled experiments in human metabolism were published by Santorio Santorio in 1614 in his book Ars de statica medicina ...
Acetonitrile - Safety - Toxicity - Metabolism and Excretion
... The metabolism of acetonitrile is much slower than that of other nitriles, which accounts for its relatively low toxicity ... The relatively slow metabolism of acetonitrile to hydrogen cyanide allows more of the cyanide produced to be detoxified within the body to thiocyanate (t ... The main pathways of excretion are by exhalation and in the urine ...

Famous quotes containing the word metabolism:

    He’s got a fifteen percent metabolism with an overactive thyroid and a glandular affectation of about three percent. With a one percent mentality. He’s what we designate as the Crummy Moronic type.
    Robert Pirosh, U.S. screenwriter, George Seaton, George Oppenheimer, and Sam Wood. Dr. Hugo Z. Hackenbush (Groucho Marx)