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

• Zero-order kinetics, because alcohol is metabolised by Alcohol dehydrogenase.
• The clinical significance of this is that the alcohol is being metabolised at a constant rate, no matter of the amount of alcohol that is ingested. The reason for this is that there is a limited amount of NAD (a co-enzyme) which means that NAD becomes saturated when there is too much alcohol in the body, which can cause the effects of alcohol to be more easily seen.

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

• 1. The first pathway is by means of alcohol dehydrogenase metabolism. Alcohol dehydrogenase is used for metabolising low to moderate amounts of alcohol. There is a limited amount of NAD, a co-enzyme, which means that this metabolism takes place with zero-order kinetics, an amount of 7-10g is metabolised per hour. The tempo of metabolism is constant.
• 2. The second pathway is by means of MEOS (microsomal ethanol oxidases). This form of metabolism is used with higher concentrations of alcohol (>100mg/dL). This metabolisms activity increases with chronic use of alcohol, metabolism can be induced and is partially responsible for tolerance.
• The end product for both of these metabolisms is acetaldehyde.

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

• Disulfiram.
• Metronidazole.
• Cephalosporins.
• Hypoglycemics.
• The effect of this is that alcohol isn’t converted into acetate from acetaldehyde with alcohol dehydrogenase enzyme. Which can lead to side effects that are normally seen as common hangover symptoms.