Which organ is primarily responsible for detoxification and metabolism of drugs?

Which organ is primarily responsible for detoxification and metabolism of drugs?

• A. Liver
• B. Heart
• C. Stomach
• D. Lungs

Answer: (A)

The liver is the primary site where drugs are detoxified and metabolized. This organ houses hepatocytes rich in drug‑metabolizing enzymes, especially the cytochrome P450 system, which carry out Phase I reactions (oxidation, reduction, hydrolysis) to modify a drug's structure. After these changes, Phase II reactions attach water‑soluble groups through conjugation (such as glucuronidation, sulfation, or glutathione conjugation), making the drug easier to excrete. For many oral medications, the liver receives drug-rich blood first via the hepatic portal vein, so a portion of the drug is inactivated or altered before reaching systemic circulation—a phenomenon known as first‑pass metabolism. The liver also exports metabolites into bile for elimination. While other organs contribute in smaller or more limited ways, the liver does most of the work in detoxifying and metabolizing drugs.

The liver is the primary site where drugs are detoxified and metabolized. This organ houses hepatocytes rich in drug‑metabolizing enzymes, especially the cytochrome P450 system, which carry out Phase I reactions (oxidation, reduction, hydrolysis) to modify a drug's structure. After these changes, Phase II reactions attach water‑soluble groups through conjugation (such as glucuronidation, sulfation, or glutathione conjugation), making the drug easier to excrete. For many oral medications, the liver receives drug-rich blood first via the hepatic portal vein, so a portion of the drug is inactivated or altered before reaching systemic circulation—a phenomenon known as first‑pass metabolism. The liver also exports metabolites into bile for elimination. While other organs contribute in smaller or more limited ways, the liver does most of the work in detoxifying and metabolizing drugs.