Adult-Gerontology Clinical Nurse Specialist (CNS) Practice Exam

After an orally administered drug enters the body, which of the following does it NOT interact with during first-pass metabolism?

1. Bacterial enzymes in the intestine

2. CYP 450 enzymes in the liver

3. Permeability glycoprotein

4. Cytochrome 470 enzymes present in gastrointestinal cells

The correct answer is: Cytochrome 470 enzymes present in gastrointestinal cells

First-pass metabolism refers to the process where the concentration of a drug is significantly reduced before it reaches systemic circulation, primarily due to metabolism in the liver and the gastrointestinal (GI) tract. The correct choice is associated with the specific enzymes involved in this metabolism and where they are located. Cytochrome 470 enzymes do not play a key role in first-pass metabolism compared to the other options. These enzymes are not defined or prominent in the context of drug metabolism, which typically involves cytochrome P450 enzymes that are crucial in the liver for drug processing. Unlike the various enzymes in the liver and cells of the gastrointestinal tract that actively metabolize drugs and influence their pharmacokinetics during the first-pass effect, cytochrome 470 enzymes are not recognized in this capacity, making this option the one that does not interact with the drug during first-pass metabolism. In contrast, bacterial enzymes in the intestine, CYP 450 enzymes in the liver, and permeability glycoprotein all play significant roles. Bacterial enzymes can participate in biotransformation processes within the gut, which may affect drug absorption and disposition. CYP 450 enzymes in the liver are central to drug metabolism, while permeability glycoprotein can influence the absorption and distribution of drugs by