Which organs are involved in drug metabolism?

Which organs are involved in drug metabolism?

• A. Kidney
• B. Spleen
• C. Liver (Main Organ) and Plasma, Lungs, GI, Kidneys, Heart, Brain, and Skin
• D. Adipose Tissue

Answer: (C)

Drug metabolism occurs mainly in the liver because it houses a high concentration of metabolic enzymes (especially cytochrome P450s and conjugating systems) that transform lipophilic drugs into more polar, excretable forms. But metabolism isn’t limited to the liver. Extrahepatic sites contribute as well: plasma contains hydrolases that can rapidly hydrolyze ester- and amide-containing prodrugs; the lungs can metabolize certain inhaled agents; the GI tract wall (enterocytes) adds first-pass and gut-wall metabolism; the kidneys have renal enzymes that metabolize drugs during excretion; and tissues like the heart, brain, skin, and adipose tissue can perform smaller amounts of metabolic processing. So the liver is the main organ, with these other tissues participating to varying degrees.

Drug metabolism occurs mainly in the liver because it houses a high concentration of metabolic enzymes (especially cytochrome P450s and conjugating systems) that transform lipophilic drugs into more polar, excretable forms. But metabolism isn’t limited to the liver. Extrahepatic sites contribute as well: plasma contains hydrolases that can rapidly hydrolyze ester- and amide-containing prodrugs; the lungs can metabolize certain inhaled agents; the GI tract wall (enterocytes) adds first-pass and gut-wall metabolism; the kidneys have renal enzymes that metabolize drugs during excretion; and tissues like the heart, brain, skin, and adipose tissue can perform smaller amounts of metabolic processing. So the liver is the main organ, with these other tissues participating to varying degrees.