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

Alcohol is a water-soluble molecule that is quickly absorbed from the gastrointestinal tract. Alcohol's high lipophilicity allows for rapid passage through the blood-brain barrier and into the central nervous system. In a fasting state, peak alcohol levels in the blood can be seen within 30 minutes of intake. The total fluid in the body plays an important role in alcohol distribution; the more body fluids there are, the longer it takes for the alcohol concentration to reach toxic levels. The liver (90 percent of the time) metabolizes alcohol using two enzyme systems: Alcohol Dehydrogenase and MEOS (mixed function oxidases).

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

The Alcohol Dehydrogenase System and MEOS are the two enzyme systems in the liver that are responsible for the metabolism of alcohols (ethanol).
The Alcohol Dehydrogenase system uses zero-order kinetics to catalyze the conversion of alcohol to acetaldehyde, resulting in the pathway becoming saturated and independent of ethanol concentration. This pathway uses NAD as a co-enzyme to metabolize low to moderate levels of alcohol [7-10g/h]. The Microsomal Ethanol-oxidizing Mechanism (MEOS) is in charge of converting ethanol to Acetaldehyde at higher concentrations [>100mg/dL]. Its activity can be caused by consuming alcohol on a regular basis. Aldehyde-dehydrogenase transforms acetaldehyde to acetate, which is then broken down into carbon dioxide and water and excreted through the urine or used to make Acetyl Co-A.

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

Disulfiram, metronidazole, cephalosporin, and hypoglycaemic drugs are all drugs that affect alcohol metabolism. As a result of the drug's inhibition of Aldehyde Dehydrogenase, the body accumulates Acetaldehyde. Acetaldehyde concentrations in the body can induce the same harmful effects as heavy drinking, such as nausea, vomiting, ataxia, headaches, and so on.

References:

Katzung, B.G. 2018. Basic and Clinical Pharmacology. 14th ed. United States of America: McGraw-Hill Education.