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

The metabolism of alcohol is a very important kinetic. There are two enzyme systems that contribute to the metabolism of alcohol. Acetaldehyde is the end product of both of these systems.

- Alcohol dehydrogenase – this system is activated when low to moderate amounts of alcohol is ingested. Due to the limited amount of NAD co-enzymes, zero order kinetics will be seen which means when these co-enzymes are depletes, the system becomes saturated and the alcohol will not be metabolised, this will or can lead to a build of alcohol (ethanol molecules).

- MEOS – this system is activated to higher concentrations of alcohol present in the blood (>100mg/dL). This activity will increase due to chronic use, thus can lead to tolerance, because patient ingest lots of alcohol, but feel fine due to the rapid metabolism of the MEOS, but this is not good because even if they feel fine at 400mg/dL the body can only handle a certain amount of BAC and thus can lead to instant death if more alcohol is ingested.

Sometimes certain drugs can block the Aldehydedehidrogenase enzyme that breaks acetaldehyde down – this will lead to a hangover effect.

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

Referring to Katzung textbook p. 397. It can be seen that ethanol is metabolised by the two enzyme systems as mentioned above. Where acetaldehyde is the end product. This product is broken down by the enzyme Aldehydedehidrogenase, leading to the formation of actetate that can be excreted by the body.

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

• Disulfiram
• Metronidazole
• Cephalosporine
• Hypopglycemics

This will ensure an acetaldehyde build up that will let the patient feel nauseas or experience a headache. This effects are seen because acetate cannot be formed which will convert to CO₂ and water to be excreted.