The liver has an important role in drug ADME. Which ONE of the following is CORRECT?

Question

BlackTom AI · Accepted Answer

The question asks us to identify which statement about liver roles in drug ADME is correct.
Option 1: 'In phase I biotransformation drugs are converted into more hydrophobic metabolites.' This is misleading. Phase I reactions (e.g., oxidation, reduction, hydrolysis) often introduce or expose polar groups, not increase hydrophobicity; in many cases metabolites become more polar to aid excretion. So this is not accurate.
Option 2: 'Hepatic P450 enzymes mediate drug conjugation.' Cytochrome P450 enzymes primarily carry out oxidative phase I reactions. Conjugation steps (phase II) such as glucuronidation, sulfation, and acetylation are typically mediated by distinct transferase enzymes. Therefore this statement is incorrect.
Option 3: 'The first pass effect is greater if the activity of hepatic biotransformation enzymes is low.' In reality, a higher enzymatic activity in the liver increases the first-pass metabolism, reducing systemic bioavailability after oral dosing. If enzyme activity is low, the first-pass effect would be smaller. Hence this option is incorrect.
Option 4: 'After oral absorption drugs enter the liver via the portal vein.' Correct. After absorption from the gut, orally administered drugs are delivered to the liver through the hepatic portal vein, exposing them to first-pass metabolism before reaching systemic circulation.

In summary, the only statement that aligns with the known anatomy and metabolism of drugs is the fourth option, which correctly describes the route of oral drugs to the liver via the portal circulation, initiating first-pass exposure.

The liver has an important role in drug ADME. Which ONE of the following is CORRECT?Single choice

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