Understanding the Pharmacology of Ethanol
How we process Alcohol by Dr. David Benjamin, PhD,
Clinical Pharmacologist & Toxicologist

Basic Pharmacology of Ethanol

Ethyl alcohol (ethanol, ETOH) or just alcohol has been described as the "perfect" drug. It is soluble in water, the major constituent of all bodily fluids and tissues, not charged, a small molecule and not subject to changes in molecular structure as a result of changes in the acidity (pH) of the body fluids. Because ETOH is uncharged, it is also soluble in fatty substances (i.e., lipids) and passes easily through the lipid membrane barriers in the body (e.g., from the stomach into the blood or from the intestines into the blood).

Ethanol, like all drugs undergoes four scientific or pharmacokinetic processes in the body:

1. ABSORPTION
2. DISTRIBUTION
3. METABOLISM
4. EXCRETION

These four processes occur contemporaneously until (1) all the alcohol is absorbed from the GI tract, and there is no more absorption phase, and (2) all the alcohol has been metabolized, and there is no more metabolism of ETOH and it is no longer detectable in the blood.

In order to simplify the pharmacokinetic model, many authors refer to a "plateau" phase instead of a "peak" blood level, a diffusion-equilibrium phase instead of a distribution phase, and an elimination phase which combines the processes of metabolism and excretion.