Physiology The first step in alcohol metabolism by the liver is the formation of acetaldehyde from alcohol, a chemical reaction catalyzed by: A Cytochrome P450 B NADPH-cytochrome reductase P450 C Alcohol oxygenase D Alcohol dehydrogenase 💡 Explanation The first step in alcohol metabolism by the liver is the formation of acetaldehyde from alcohol, a chemical reaction catalyzed by: ✓ Correct Answer: D. Alcohol dehydrogenase