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

• Alcohol follows zero-order kinetics as 1g/hours is metabolised for every 10kg of body weight.
• This is clinically significant because it shows that there is a linear relationship between alcohol and the metabolism rate and is used as a measure of how much alcohol content is in a person’s blood and how much will be excreted during one hour

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

• There are 2 systems: the alcohol dehydrogenase pathway and the microsomal ethanol-oxidising system (MEOS)
• Alcohol dehydrogenase pathway: alcohol dehydrogenase (ADH) catalyses the conversion of alcohol to acetaldehyde. During this conversion, a hydrogen ion is transferred from ethanol to nicotinamide adenine dinucleotide to form NADH, thus there is a low to moderate amount of NADH
• MEOS: NADPH (made up of cytochrome P450, 2E1, 1A2 and 3A4) is the cofactor in ethanol metabolism. With chronic alcohol consumption, MEOS activity is induced therefore there is an increase in ethanol metabolism 

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

• Drugs that inhibit aldehyde dehydrogenase (ALDH) (eg disulfiram, metronidazole, cephalosporins and hypoglycaemics) which can cause a build-up of the ALDH which can cause nausea, vomiting and headaches