STUDY UNIT 3.1

• What type of kinetics applies for alcohol in the body? Also, explain the clinical significance of this.

First-order and Zero-order kinetics. Alcohol is a small water soluble molecule and is absorbed rapidly in the GIT. Distribution is rapid with tissue levels approximating the concentration in blood. In the CNS, ethanol concentrations rise quickly because the bran receives a large portion from the total blood flow and ethanol readily crosses biological membranes.

• Give a brief summary of the metabolic pathways of ethanol metabolism.

1. Alcohol dehydrogenase pathway, this is the primary pathway of alcohol metabolism. It converts alcohol to acetaldehyde. These enzymes are found mainly in the liver but small amounts are found in the brain and stomach as well. This metabolic pathway can only meatbolise small to moderate amounts of alcohol

 (7-10g) due to the limited amount of NAD which also makes it a zero-order kinetic process.

2. Microsomal ethanol-oxidising systems, this type of metabolism is used fro high levels of alcohol consumption and in chronic alcohol consumption. Uses NADPH as a cofactor in the metabolism of ethanol. MEOS activity increases with chronic use and can be induced resulting in tolerance.

• Which drugs can affect this metabolism and what are the effects thereof?

Disfulfiram 

Metronidazole

Hypoglycemic drugs 

Cephalosprorins 

These drugs, inhibit the oxidation of acetaldehyde, thus causing a build-up of acetaldehyde resulting in an unpleasant reaction such as. Nausea, vomiting, dizziness, headache etc.