Question

Which statement about the meaning of first-pass effect is incorrect?

a. "The first-pass effect means the drug may be changed to an inactive form and excreted."
b. "The first-pass effect means the drug may be absorbed into systemic circulation from the intestinal lumen."
c. "The first-pass effect means the drug may be unchanged as it passes through the liver."
d. "The first-pass effect means the drug may be changed to a metabolite, which may be more active than the original."

Answer 1

The incorrect statement is that the first-pass effect refers to absorption into systemic circulation from the intestinal lumen. It actually describes metabolism before reaching systemic circulation, often resulting in a drug being metabolized to an inactive form, unchanged, or a more active metabolite.

Step-by-step explanation:

The incorrect statement about the meaning of the first-pass effect is "The first-pass effect means the drug may be absorbed into systemic circulation from the intestinal lumen." This statement is incorrect because the first-pass effect refers to the reduction in the concentration of a drug before it reaches systemic circulation due to metabolism, primarily in the liver and also in the gut wall. The first-pass effect can result in metabolites that are either more or less active than the original drug or even completely inactive.

Drugs absorbed from the gastrointestinal tract enter the portal circulation and pass through the liver where they may be metabolized before reaching the systemic circulation. This metabolism can lead to the drug being changed to an inactive form and then excreted, remaining unchanged, or being changed to a metabolite, which in some cases may be more active than the original drug.