Which organ is responsible for most drug metabolism?

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Multiple Choice

Which organ is responsible for most drug metabolism?

Metabolism is about converting drugs into more water-soluble forms to facilitate elimination. The liver is the primary site because it houses the largest and most diverse set of drug‑metabolizing enzymes, especially the cytochrome P450 family along with Phase II conjugating systems like UGTs and SULTs. Through Phase I reactions (oxidation, reduction, hydrolysis) and Phase II reactions (glucuronidation, sulfation, acetylation), the liver transforms lipophilic drugs into metabolites that are easier to excrete in urine or bile. When drugs are taken orally, the liver also creates a first‑pass effect via the portal circulation, which can substantially reduce the amount that reaches systemic circulation if extensively metabolized. Other organs contribute some metabolism, but their overall role is much smaller than the liver’s.

Metabolism is about converting drugs into more water-soluble forms to facilitate elimination. The liver is the primary site because it houses the largest and most diverse set of drug‑metabolizing enzymes, especially the cytochrome P450 family along with Phase II conjugating systems like UGTs and SULTs. Through Phase I reactions (oxidation, reduction, hydrolysis) and Phase II reactions (glucuronidation, sulfation, acetylation), the liver transforms lipophilic drugs into metabolites that are easier to excrete in urine or bile. When drugs are taken orally, the liver also creates a first‑pass effect via the portal circulation, which can substantially reduce the amount that reaches systemic circulation if extensively metabolized. Other organs contribute some metabolism, but their overall role is much smaller than the liver’s.

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