Absorption, Distribution, and Elimination of Alcohol

• Author: James G. Wigmore
• Pages: 1-74

 

 

Absorption, Distribution, and Elimination

of Alcohol

The absorption, distribution, and elimination of alcohol, the focus of

this chapter, are also known as the pharmacokinetics of alcohol. Phar-

macokinetics is basical ly the study of what the body does to a drug: how

the drug is absorbed, dis tributed, and metabolized by the various organs

of the body. Although the pharmacokinetics of alcohol has been d ivided

into the separate topics of absorption, distribution, and elimination, it

should be emphasized that these processes occur nea rly simultaneously

in the body.

When the absorption of alcohol is greater than the elimination, the

blood alcohol concentration (BAC) increases. When absorption is slowed

down, such as with the ingestion of food, and absorpt ion is equal to elimin-

ation, a plateau occurs in which the BAC apparently does not change. When

absorption is less than elimi nation, a decrease in the BAC occurs that is

basically linea r until all the alcohol has been eliminated f rom the body.

Absorption > Elimination → BAC Increases

Absorption = Elimination → BAC Plateaus

Absorption < Elimination → BAC Decreases

If there is rapid absorption of alcohol from quick oral drink ing or

intravenous infusion, then distribution may lag behind absorption and

result in a signif‌icantly higher alcohol concentration in the arterial

blood than the venous blood (arteriovenous [AV] lag).

The typical drinking patter ns and pharmacokinetics of drinking

drivers are also discussed in this chapter, as well as the extrapolation

or back calculations of the BAC of the drink ing driver to an earlier time.

  Wigmore on Alcohol

Reference Number: 

Widmark (or forward) BAC calculations, which are generally much less

reliable than back calcu lations, are presented in section .. The ef‌fects

of other drugs (e.g., cimetidine) and of trauma are covered in sections

. and ., respectively.

. ABSORPTION

Alcohol is generally absorbed after oral consumption via the stomach

and small intestine. Alcohol is a unique drug in that it can be substan-

tially absorbed via t he stomach (–), although absorption through

the small intestine is faster. The concentration of alcohol in the stom-

ach decreases rapidly, so it is rarely benef‌icial to lavage or remove the

contents of the stomach in alcohol-intoxicated patients as usually only

minimal a mounts of alcohol remain in the stomach by the time the pa-

tient presents to hospital ().

Food ingestion tends to slow the absorption of alcohol and decrease

the maximum BAC, but it does not substantia lly prolong the time to

peak BAC (–). Carbonation tends to cause a more rapid absorp-

tion of alcohol and increase the initial BAC (, ), but salty

foods and warm temperatures of alcoholic beverages do not signif‌icant-

ly change the rate of alcohol absorption (, ). Various gastric

surgeries such as a gastric bypass may substantially increase the rate of

alcohol absorption, and patients who undergo these operations should

be warned of this ef‌fect ().

Alcohol is not signif‌icantly absorbed by inha lation through the lungs

(–) or via dif‌fusion th rough the skin (, , , ).

Hence, frequent use of an alcohol-based hand sanitizer does not result

in a signif‌icant BAC (, ). Alcohol can be rapidly absorbed by

intravenous infusion (, ) or by rectal enema ().

Reference Number: 

, ..,  . . “The Absorption of Ethyl Alcohol from

the Gastro-Intestinal Tract as a Dif‌fusion Process.” Acta Physiologica

Scandinavia, /: –, / ( tables,  f‌igures,  references)

Abstract: The absorption of alcohol from the stomach was determined

in cats and humans. Several human subjects were admi nistered up to

 mL of a % or % alcohol solution via a stomach tube. The stomach

alcohol concentration was then determined over time. A mathematical

Absorption, Distribution, and Elimination of Alcohol  

Reference Number: 

model (based on Fick’s law) of the dif‌fusion process was presented. In

human subjects with a closed pylorus, approximately % of the alcohol

was absorbed after  minutes, % after  minutes, a nd % after 

minutes. If the stomach was empty, % of the alcohol was able to be

absorbed within  minutes. Tests were also conducted on patients with

gastritis and ach lorhydria (associated with severe anemias a nd stomach

cancer), and no signif‌icant dif‌ferences in alcohol absorption from the

stomach were observed compared with that in normal s ubjects.

Table. Percent of Alcohol Absorbed from the Stomach and

Stomach Emptying Time in Five Normal Subjects after

Instillation of  mL of % Alcohol Solution

Percent Alcohol Absor bed from

Stomach

Time of Stomach Emptyin g

(min)

Subject No.  min  min

  

  

  

  

  

 = not available.

Source: Adapted from Berggren an d Goldberg (/).

The absorption of ethyl alcohol from the stomach follows the laws of

dif‌fusion. This means that the greater the concentration of alcohol in -

gested, the more rapidly absorption will t ake place with a higher and

earlier blood alcohol maximum.

Reference Number: 

, .. “The Simultaneous Emptying and Absorption of Ethanol from

the Human Stomach.” Digestive Diseases, : –,  ( tables, 

f‌igures,  references)

Abstract: A total of  meals ( of water and  of .% volume of sol-

ute per volume of solvent [v/v] ethanol) were given to seven healthy, fast-

ing subjects. The volume of the meals was  mL . Gastric contents were

aspirated at various times, a nd the alcohol concentration was measured

by an alcohol dehydrogenase (ADH) procedure. The emptying of ethanol

meals and water meals proceeded at the same rate up to about  min-

utes, when about % of the meal had left the stomach. The absorption