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

Alcohol is lipophilic, meaning it is rapidly absorbed and distributed across the blood brain barrier.

Food in the stomach decreases the gastric emptying rate and thereby decreases alcohol absorption. It is for this reason that when in a fasting state, alcohol administered can reach its peak concentration within 30 minutes. Total body water content also plays a role in the absorption of alcohol: women have less body water than men do and it is for this reason that the absorption of alcohol reaches its peak concentration faster in women than in men. 

Over 90% of alcohol consumed is oxidized in the liver, and the remainder is excreted through the lungs and urine. The rate of alcohol oxidation follows zero order kinetics. It is independent of time and concentration of the drug. The typical adult can metabolize 7-10g of alcohol per hour.  

Give a brief summary of the metabolic pathways of ethanol metabolism

Metabolism of ethanol to acetaldehyde occurs via two major pathways:

1. Alcohol dehydrogenase system: This is the primary pathway for alcohol metabolism . Cytosolic enzymes catalyze the conversion of alcohol to acetaldehyde. These enzymes are mainly located in the liver, but are also found in smaller amounts in the brain and stomach. Women have lower amounts of gastric enzyme than men do, therefore accounting for the lower rate of alcohol metabolism in the stomach than men. During the conversion of ethanol by ADH to acetaldehyde, hydrogen ion is transferred from ethanol to the cofactor nicotinamide adenine dinucleotide (NAD) to form NADH. As a net result, alcohol oxidation generates an excess of reducing equivalents in the liver, chiefly as NADH. 
2. Microsomal ethanol oxidizing system (MEOS): This enzyme system uses NADPH as a cofactor in the metabolism of alcohol and consists primarily of CYP450, 2E1, 1A2 and 3A4. Alcohol is metabolized to acetaldehyde and acetaldehyde will be converted by aldehyde dehydrogenase to acetate. 

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

Disulfiram, Metronidazole, Cefotetan and Trimethoprim can inhibit the oxidation of acetaldehyde to acetate, by inhibiting Aldehyde dehydrogenase. This can result in acetaldehyde to accumulate and thus cause side effects such as: facial flushing, nausea, vomiting, dizziness, and headaches. 

Source

Katzung, B.G. 2018. Basic & Clinical Pharmacology. 14th ed. New York: Mc Graw Hill Education