Alcohol is absorbed from all parts of the gastrointestinal tract largely by simple diffusion into the blood. However the small intestine is by far the most efficient region of the gastrointestinal tract for alcohol absorption because of its very large surface area. In a fasting individual, it is generally agreed that 20% to 25% of a dose of alcohol is absorbed from the stomach and 75% to 80% is absorbed from the small intestine. Because of this peak blood alcohol concentrations are achieved in fasting people within 0.5 to 2.0 hours, while non-fasting people exhibit peak alcohol concentrations within 1.0 to as much as 6.0 hours.
Alcohol has a high affinity for water and is therefore found in body tissues and fluids inasmuch as they contain water. Absorbed alcohol is rapidly carried throughout the body in the blood and once absorption of alcohol is complete an equilibrium occurs such that blood at all points in the system contains approximately the same concentration of alcohol.
The liver is responsible for the elimination - through metabolism - of 95% of ingested alcohol from the body. The remainder of the alcohol is eliminated through excretion of alcohol in breath, urine, sweat, feces, milk and saliva. The body uses several different metabolic pathways in its oxidation of alcohol to acetaldehyde to acetic acid to carbon dioxide and water.
Healthy people metabolize alcohol at a fairly consistent rate. As a rule of thumb, a person will eliminate one average drink or .5 oz (15 ml) of alcohol per hour. Several factors influence this rate. The rate of elimination tends to be higher when the blood alcohol concentration in the body is very high or very low. Also chronic alcoholics may (depending on liver health) metabolize alcohol at a significantly higher rate than average. Finally, the body's ability to metabolize alcohol quickly tend to diminish with age.
Stages of Alcohol Intoxication
The following is a generally accepted guide to the affects of alcohol.
0.01 - 0.05 (Subclinical)
Behavior nearly normal by ordinary observation
0.03 - 0.12 (Euphoria)
Mild euphoria, sociability, talkativeness, increased self-confidence; decreased inhibitions, diminution of attention, judgment and control, beginning of sensory-motor impairment, loss of efficiency in finer performance tests
0.09 - 0.25 (Excitement)
Emotional instability, loss of critical judgment, impairment of perception, memory and comprehension, decreased
sensatory response, increased reaction time, reduced visual acuity, peripheral vision and glare recovery, sensory-motor incoordination, impaired balance, drowsiness
0.18 - 0.30 (Confusion)
Disorientation, mental confusion; dizziness, exaggerated emotional states, disturbances of vision and of perception of color, form, motion and dimensions, increased pain threshold, increased muscular incoordination, staggering gait, slurred speech, apathy, lethargy
0.25 - 0.40 (Stupor)
General inertia, approaching loss of motor functions, markedly decreased response to stimuli, marked muscular incoordination, inability to stand or walk, vomiting, incontinence, impaired consciousness, sleep or stupor
0.35 - 0.50 (Coma)
Complete unconsciousness, depressed or abolished reflexes, subnormal body temperature, incontinence