Detoxification of lipid-soluble drugs in the liver is a primary function of which organelle?

• A. Rough endoplasmic reticulum
• B. Smooth endoplasmic reticulum
• C. Golgi apparatus
• D. Mitochondrion

Answer: (B)

Detoxification of lipid-soluble drugs in the liver is carried out primarily by the smooth endoplasmic reticulum of hepatocytes. The smooth ER hosts cytochrome P450 enzymes that initiate Phase I oxidation, adding reactive groups to lipophilic compounds to make them more water-soluble and ready for further conjugation (Phase II) and excretion. This function depends on the absence of ribosomes, which is why it is distinct from the rough ER, whose job is protein synthesis with ribosomes. The Golgi apparatus then processes and packages proteins for secretion or delivery, while mitochondria focus on energy production and other metabolic tasks rather than detoxifying lipid-soluble drugs.